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Articles 1 - 29 of 29
Full-Text Articles in Medical Genetics
Signaling Through Lrg1, Rho1 And Pkc1 Governs Candida Albicans Morphogenesis In Response To Diverse Cues, Jinglin L. Xie, Nora Grahl, Trevor Sless, Michelle Leach, Sang Hu Kim, Deborah Hogan
Signaling Through Lrg1, Rho1 And Pkc1 Governs Candida Albicans Morphogenesis In Response To Diverse Cues, Jinglin L. Xie, Nora Grahl, Trevor Sless, Michelle Leach, Sang Hu Kim, Deborah Hogan
Dartmouth Scholarship
The capacity to transition between distinct morphological forms is a key virulence trait for diverse fungal pathogens. A poignant example of a leading opportunistic fungal pathogen of humans for which an environmentally responsive developmental program underpins virulence is Candida albicans. C. albicans mutants that are defective in the transition between yeast and filamentous forms typically have reduced virulence. Although many positive regulators of C. albicans filamentation have been defined, there are fewer negative regulators that have been implicated in repression of filamentation in the absence of inducing cues. To discover novel negative regulators of filamentation, we screened …
Links Between Anr And Quorum Sensing In Pseudomonas Aeruginosa Biofilms, John H. Hammond, Emily F. Dolben, T. Jarrod Smith, Sabin Bhuju, Deborah Hogan
Links Between Anr And Quorum Sensing In Pseudomonas Aeruginosa Biofilms, John H. Hammond, Emily F. Dolben, T. Jarrod Smith, Sabin Bhuju, Deborah Hogan
Dartmouth Scholarship
In Pseudomonas aeruginosa, the transcription factor Anr controls the cellular response to low oxygen or anoxia. Anr activity is high in oxygen-limited environments, including biofilms and populations associated with chronic infections, and Anr is necessary for persistence in a model of pulmonary infection. In this study, we characterized the Anr regulon in biofilm-grown cells at 1% oxygen in the laboratory strain PAO1 and in a quorum sensing (QS)-deficient clinical isolate, J215. As expected, transcripts related to denitrification, arginine fermentation, high-affinity cytochrome oxidases, and CupA fimbriae were lower in the Δanr derivatives. In addition, we observed that transcripts associated with quorum …
Clustered Regularly Interspaced Short Palindromic Repeat-Dependent, Biofilm-Specific Death Of Pseudomonas Aeruginosa Mediated By Increased Expression Of Phage-Related Genes, Gary E. E. Heussler, Kyle C. Cady, Katja Koeppen, Sabin Bhuju, Bruce A. Stanton, George A. O’Toole
Clustered Regularly Interspaced Short Palindromic Repeat-Dependent, Biofilm-Specific Death Of Pseudomonas Aeruginosa Mediated By Increased Expression Of Phage-Related Genes, Gary E. E. Heussler, Kyle C. Cady, Katja Koeppen, Sabin Bhuju, Bruce A. Stanton, George A. O’Toole
Dartmouth Scholarship
The clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (CRISPR/Cas) system is an adaptive immune system present in many archaea and bacteria. CRISPR/Cas systems are incredibly diverse, and there is increasing evidence of CRISPR/Cas systems playing a role in cellular functions distinct from phage immunity. Previously, our laboratory reported one such alternate function in which the type 1-F CRISPR/Cas system of the opportunistic pathogen Pseudomonas aeruginosa strain UCBPP-PA14 (abbreviated as P. aeruginosa PA14) inhibits both biofilm formation and swarming motility when the bacterium is lysogenized by the bacteriophage DMS3. In this study, we demonstrated that the presence of just the DMS3 …
Analysis Of Clock-Regulated Genes In Neurospora Reveals Widespread Posttranscriptional Control Of Metabolic Potential, Jennifer M. M. Hurley, Arko Dasgupta, Jillian M. Emerson, Xiaoying Zhou, Carol S. Ringelberg, Nicole Knabe
Analysis Of Clock-Regulated Genes In Neurospora Reveals Widespread Posttranscriptional Control Of Metabolic Potential, Jennifer M. M. Hurley, Arko Dasgupta, Jillian M. Emerson, Xiaoying Zhou, Carol S. Ringelberg, Nicole Knabe
Dartmouth Scholarship
Neurospora crassa has been for decades a principal model for filamentous fungal genetics and physiology as well as for understanding the mechanism of circadian clocks. Eukaryotic fungal and animal clocks comprise transcription-translation-based feedback loops that control rhythmic transcription of a substantial fraction of these transcriptomes, yielding the changes in protein abundance that mediate circadian regulation of physiology and metabolism: Understanding circadian control of gene expression is key to understanding eukaryotic, including fungal, physiology. Indeed, the isolation of clock-controlled genes (ccgs) was pioneered in Neurospora where circadian output begins with binding of the core circadian transcription factor WCC to a subset …
E2f4 Regulatory Program Predicts Patient Survival Prognosis In Breast Cancer, Sari S. Khaleel, Erik H. Andrews, Matthew Ung, James Direnzo, Chao Chung
E2f4 Regulatory Program Predicts Patient Survival Prognosis In Breast Cancer, Sari S. Khaleel, Erik H. Andrews, Matthew Ung, James Direnzo, Chao Chung
Dartmouth Scholarship
Genetic and molecular signatures have been incorporated into cancer prognosis prediction and treatment decisions with good success over the past decade. Clinically, these signatures are usually used in early-stage cancers to evaluate whether they require adjuvant therapy following surgical resection. A molecular signature that is prognostic across more clinical contexts would be a useful addition to current signatures. We defined a signature for the ubiquitous tissue factor, E2F4, based on its shared target genes in multiple tissues. These target genes were identified by chromatin immunoprecipitation sequencing (ChIP-seq) experiments using a probabilistic method. We then computationally calculated the regulatory activity score …
H-Ns Binding And Repression Of The Ctx Promoter In Vibrio Cholerae, Emily A. Stonehouse, Robin R. Hulbert, Melinda B. Nye, Karen Skorupski, Ronald K. Taylor
H-Ns Binding And Repression Of The Ctx Promoter In Vibrio Cholerae, Emily A. Stonehouse, Robin R. Hulbert, Melinda B. Nye, Karen Skorupski, Ronald K. Taylor
Dartmouth Scholarship
Expression of the ctx and tcp genes, which encode cholera toxin and the toxin coregulated pilus, the Vibrio cholerae O1 virulence determinants having the largest contribution to cholera disease, is repressed by the nucleoid-associated protein H-NS and activated by the AraC-like transcriptional regulator ToxT. To elucidate the molecular mechanism by which H-NS controls transcription of the ctxAB operon, H-NS repression and binding were characterized by using a promoter truncation series, gel mobility shift assays, and DNase I footprinting. Promoter regions found to be important for H-NS repression correlated with in vitro binding. Four main H-NS binding regions are present at …
Interconnections Between Sigma B, Agr, And Proteolytic Activity In Staphylococcus Aureus Biofilm Maturation, Katherine J. Lauderdale, Blaise R. Boles, Ambrose L. Cheung, Alexander R. Horswill
Interconnections Between Sigma B, Agr, And Proteolytic Activity In Staphylococcus Aureus Biofilm Maturation, Katherine J. Lauderdale, Blaise R. Boles, Ambrose L. Cheung, Alexander R. Horswill
Dartmouth Scholarship
Staphylococcus aureus is a proficient biofilm former on host tissues and medical implants. We mutagenized S. aureus strain SH1000 to identify loci essential for ica-independent mechanisms of biofilm maturation and identified multiple insertions in the rsbUVW-sigB operon. Following construction and characterization of a sigB deletion, we determined that the biofilm phenotype was due to a lack of sigma factor B (SigB) activity. The phenotype was conserved in a sigB mutant of USA300 strain LAC, a well-studied community-associated methicillin-resistant S. aureus isolate. We determined that agr RNAIII levels were elevated in the sigB mutants, and high levels of RNAIII expression are …
Identification Of Two Gene Clusters And A Transcriptional Regulator Required For Pseudomonas Aeruginosa Glycine Betaine Catabolism, Matthew J. Wargo, Benjamin S. Szwergold, Deborah A. Hogan
Identification Of Two Gene Clusters And A Transcriptional Regulator Required For Pseudomonas Aeruginosa Glycine Betaine Catabolism, Matthew J. Wargo, Benjamin S. Szwergold, Deborah A. Hogan
Dartmouth Scholarship
Glycine betaine (GB), which occurs freely in the environment and is an intermediate in the catabolism of choline and carnitine, can serve as a sole source of carbon or nitrogen in Pseudomonas aeruginosa. Twelve mutants defective in growth on GB as the sole carbon source were identified through a genetic screen of a nonredundant PA14 transposon mutant library. Further growth experiments showed that strains with mutations in two genes, gbcA (PA5410) and gbcB (PA5411), were capable of growth on dimethylglycine (DMG), a catabolic product of GB, but not on GB itself. Subsequent nuclear magnetic resonance (NMR) experiments with 1,2-(13)C-labeled choline …
Cif Is Negatively Regulated By The Tetr Family Repressor Cifr, Daniel P. Maceachran, Bruce A. Stanton, George A. O'Toole
Cif Is Negatively Regulated By The Tetr Family Repressor Cifr, Daniel P. Maceachran, Bruce A. Stanton, George A. O'Toole
Dartmouth Scholarship
We previously reported that the novel Pseudomonas aeruginosa toxin Cif is capable of decreasing apical membrane expression of the cystic fibrosis transmembrane conductance regulator (CFTR). We further demonstrated that Cif is capable of degrading the synthetic epoxide hydrolase (EH) substrate S-NEPC [(2S,3S)-trans-3-phenyl-2-oxiranylmethyl 4-nitrophenol carbonate], suggesting that Cif may be reducing apical membrane expression of CFTR via its EH activity. Here we report that Cif is capable of degrading the xenobiotic epoxide epibromohydrin (EBH) to its vicinal diol 3-bromo-1,2-propanediol. We also demonstrate that this epoxide is a potent inducer of cif gene expression. We show that the predicted TetR family transcriptional …
Let-7 Expression Defines Two Differentiation Stages Of Cancer, Scott Shell, Sun-Mi Park, Amir Reza Radjabi, Robert Schickel, Emily Kistner, David Jewell
Let-7 Expression Defines Two Differentiation Stages Of Cancer, Scott Shell, Sun-Mi Park, Amir Reza Radjabi, Robert Schickel, Emily Kistner, David Jewell
Dartmouth Scholarship
The early phases of carcinogenesis resemble embryonic development, often involving the reexpression of embryonic mesenchymal genes. The NCI60 panel of human tumor cell lines can genetically be subdivided into two superclusters (SCs) that correspond to CD95 Type I and II cells. SC1 cells are characterized by a mesenchymal and SC2 cells by an epithelial gene signature, suggesting that SC1 cells represent less differentiated, advanced stages of cancer. miRNAs are small 20- to 22-nucleotide-long noncoding RNAs that inhibit gene expression at the posttranscriptional level. By performing miRNA expression analysis on 10 Type I and 10 Type II cells, we have determined …
Bifa, A Cyclic-Di-Gmp Phosphodiesterase, Inversely Regulates Biofilm Formation And Swarming Motility By Pseudomonas Aeruginosa Pa14, Sherry L. Kuchma, Kimberly M. Brothers, Judith H. Merritt, Nicole T. Liberati, Frederick M. Ausubel, George A. O'Toole
Bifa, A Cyclic-Di-Gmp Phosphodiesterase, Inversely Regulates Biofilm Formation And Swarming Motility By Pseudomonas Aeruginosa Pa14, Sherry L. Kuchma, Kimberly M. Brothers, Judith H. Merritt, Nicole T. Liberati, Frederick M. Ausubel, George A. O'Toole
Dartmouth Scholarship
The intracellular signaling molecule, cyclic-di-GMP (c-di-GMP), has been shown to influence bacterial behaviors, including motility and biofilm formation. We report the identification and characterization of PA4367, a gene involved in regulating surface-associated behaviors in Pseudomonas aeruginosa. The PA4367 gene encodes a protein with an EAL domain, associated with c-di-GMP phosphodiesterase activity, as well as a GGDEF domain, which is associated with a c-di-GMP-synthesizing diguanylate cyclase activity. Deletion of the PA4367 gene results in a severe defect in swarming motility and a hyperbiofilm phenotype; thus, we designate this gene bifA, for biofilm formation. We show that BifA localizes to the inner …
P53 Activation By Knockdown Technologies, Mara E. Robu, Jon D. Larson, Aidas Nasevicius, Soraya Beiraghi, Charles Brenner
P53 Activation By Knockdown Technologies, Mara E. Robu, Jon D. Larson, Aidas Nasevicius, Soraya Beiraghi, Charles Brenner
Dartmouth Scholarship
Morpholino phosphorodiamidate antisense oligonucleotides (MOs) and short interfering RNAs (siRNAs) are commonly used platforms to study gene function by sequence-specific knockdown. Both technologies, however, can elicit undesirable off-target effects. We have used several model genes to study these effects in detail in the zebrafish, Danio rerio. Using the zebrafish embryo as a template, correct and mistargeting effects are readily discernible through direct comparison of MO-injected animals with well-studied mutants. We show here indistinguishable off-targeting effects for both maternal and zygotic mRNAs and for both translational and splice-site targeting MOs. The major off-targeting effect is mediated through p53 activation, as detected …
The Pseudomonas Aeruginosa Secreted Protein Pa2934 Decreases Apical Membrane Expression Of The Cystic Fibrosis Transmembrane Conductance Regulator, Daniel P. Maceachran, Siying Ye, Jennifer M. Bomberger, Deborah A. Hogan, Agnieszka Swiatecka-Urban, Bruce Stanton, George A. O'Toole
The Pseudomonas Aeruginosa Secreted Protein Pa2934 Decreases Apical Membrane Expression Of The Cystic Fibrosis Transmembrane Conductance Regulator, Daniel P. Maceachran, Siying Ye, Jennifer M. Bomberger, Deborah A. Hogan, Agnieszka Swiatecka-Urban, Bruce Stanton, George A. O'Toole
Dartmouth Scholarship
We previously reported that Pseudomonas aeruginosa PA14 secretes a protein that can reduce the apical membrane expression of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Here we report that we have used a proteomic approach to identify this secreted protein as PA2934 [corrected], and we have named the gene cif, for CFTR inhibitory factor. We demonstrate that Cif is a secreted protein and is found associated with outer membrane-derived vesicles. Expression of Cif in Escherichia coli and purification of the C-terminal six-His-tagged Cif protein showed that Cif is necessary and sufficient to mediate the reduction in apical membrane expression …
Cpg Hypomethylation In A Large Domain Encompassing The Embryonic Β-Like Globin Genes In Primitive Erythrocytes, Mei Hsu, Rodwell R. Mabaera, Christopher H. Lowrey, David I. K. Martin, Steven Fiering
Cpg Hypomethylation In A Large Domain Encompassing The Embryonic Β-Like Globin Genes In Primitive Erythrocytes, Mei Hsu, Rodwell R. Mabaera, Christopher H. Lowrey, David I. K. Martin, Steven Fiering
Dartmouth Scholarship
There is little evidence addressing the role of CpG methylation in transcriptional control of genes that do not contain CpG islands. This is reflected in the ongoing debate about whether CpG methylation merely suppresses retroelements or if it also plays a role in developmental and tissue-specific gene regulation. The genes of the β-globin locus are an important model of mammalian developmental gene regulation and do not contain CpG islands. We have analyzed the methylation status of regions in the murine β-like globin locus in uncultured primitive and definitive erythroblasts and other cultured primary and transformed cell types. A large (∼20-kb) …
Transgenic Cyclin E Triggers Dysplasia And Multiple Pulmonary Adenocarcinomas, Yan Ma, Steven Fiering, Candice Black, Xi Liu, Ziqiang Yuan, Vincent A. Memoli, David J. Robbins, Heather A. Bentley, Gregory J. Tsongalis, Eugene Demidenko, Sarah J. Freemantle, Ethan Dmitrovsky
Transgenic Cyclin E Triggers Dysplasia And Multiple Pulmonary Adenocarcinomas, Yan Ma, Steven Fiering, Candice Black, Xi Liu, Ziqiang Yuan, Vincent A. Memoli, David J. Robbins, Heather A. Bentley, Gregory J. Tsongalis, Eugene Demidenko, Sarah J. Freemantle, Ethan Dmitrovsky
Dartmouth Scholarship
Cyclin E is a critical G(1)-S cell cycle regulator aberrantly expressed in bronchial premalignancy and lung cancer. Cyclin E expression negatively affects lung cancer prognosis. Its role in lung carcinogenesis was explored. Retroviral cyclin E transduction promoted pulmonary epithelial cell growth, and small interfering RNA targeting of cyclin E repressed this growth. Murine transgenic lines were engineered to mimic aberrant cyclin E expression in the lung. Wild-type and proteasome degradation-resistant human cyclin E transgenic lines were independently driven by the human surfactant C (SP-C) promoter. Chromosome instability (CIN), pulmonary dysplasia, sonic hedgehog (Shh) pathway activation, adenocarcinomas, and metastases occurred. Notably, …
Cdx4 Dysregulates Hox Gene Expression And Generates Acute Myeloid Leukemia Alone And In Cooperation With Meis1a In A Murine Model, Dimple Bansal, Claudia Scholl, Stefan Frohling, Elizabeth Mcdowell, Benjamin H. Lee, Konstanze Döhner, Patricia Ernst
Cdx4 Dysregulates Hox Gene Expression And Generates Acute Myeloid Leukemia Alone And In Cooperation With Meis1a In A Murine Model, Dimple Bansal, Claudia Scholl, Stefan Frohling, Elizabeth Mcdowell, Benjamin H. Lee, Konstanze Döhner, Patricia Ernst
Dartmouth Scholarship
HOX genes have emerged as critical effectors of leukemogenesis, but the mechanisms that regulate their expression in leukemia are not well understood. Recent data suggest that the caudal homeobox transcription factors CDX1, CDX2, and CDX4, developmental regulators of HOX gene expression, may contribute to HOX gene dysregulation in leukemia. We report here that CDX4 is expressed normally in early hematopoietic progenitors and is expressed aberrantly in approximately 25% of acute myeloid leukemia (AML) patient samples. Cdx4 regulates Hox gene expression in the adult murine hematopoietic system and dysregulates Hox genes that are implicated in leukemogenesis. Furthermore, bone marrow progenitors that …
The Caenorhabditis Elegans Heterochronic Regulator Lin-14 Is A Novel Transcription Factor That Controls The Developmental Timing Of Transcription From The Insulin/Insulin-Like Growth Factor Gene Ins-33 By Direct Dna Binding, Marta Hristova, Darcy Birse, Yang Hong, Victor Ambros
The Caenorhabditis Elegans Heterochronic Regulator Lin-14 Is A Novel Transcription Factor That Controls The Developmental Timing Of Transcription From The Insulin/Insulin-Like Growth Factor Gene Ins-33 By Direct Dna Binding, Marta Hristova, Darcy Birse, Yang Hong, Victor Ambros
Dartmouth Scholarship
A temporal gradient of the novel nuclear protein LIN-14 specifies the timing and sequence of stage-specific developmental events in Caenorhabditis elegans. The profound effects of lin-14 mutations on worm development suggest that LIN-14 directly or indirectly regulates stage-specific gene expression. We show that LIN-14 can associate with chromatin in vivo and has in vitro DNA binding activity. A bacterially expressed C-terminal domain of LIN-14 was used to select DNA sequences that contain a putative consensus binding site from a pool of randomized double-stranded oligonucleotides. To identify candidates for genes directly regulated by lin-14, we employed DNA microarray hybridization to compare …
A Drosophila Deg/Enac Channel Subunit Is Required For Male Response To Female Pheromones, Heping Lin, Kevin J. Mann, Elena Starostina, Ronald D. Kinser, Claudio W. Pikielny
A Drosophila Deg/Enac Channel Subunit Is Required For Male Response To Female Pheromones, Heping Lin, Kevin J. Mann, Elena Starostina, Ronald D. Kinser, Claudio W. Pikielny
Dartmouth Scholarship
Odorants and pheromones as well as sweet- and bitter-tasting small molecules are perceived through activation of G protein-coupled chemosensory receptors. In contrast, gustatory detection of salty and sour tastes may involve direct gating of sodium channels of the DEG/ENaC family by sodium and hydrogen ions, respectively. We have found that ppk25, a Drosophila melanogaster gene encoding a DEG/ENaC channel subunit, is expressed at highest levels in the male appendages responsible for gustatory and olfactory detection of female pheromones: the legs, wings, and antennae. Mutations in the ppk25 gene reduce or even abolish male courtship response to females in the dark, …
A Three-Component Regulatory System Regulates Biofilm Maturation And Type Iii Secretion In Pseudomonas Aeruginosa, Sherry L. Kuchma, John P. Connolly, George A. O'Toole
A Three-Component Regulatory System Regulates Biofilm Maturation And Type Iii Secretion In Pseudomonas Aeruginosa, Sherry L. Kuchma, John P. Connolly, George A. O'Toole
Dartmouth Scholarship
Biofilms are structured communities found associated with a wide range of surfaces. Here we report the identification of a three-component regulatory system required for biofilm maturation by Pseudomonas aeruginosa strain PA14. A transposon mutation that altered biofilm formation in a 96-well dish assay originally defined this locus, which is comprised of genes for a putative sensor histidine kinase and two response regulators and has been designated sadARS. Nonpolar mutations in any of the sadARS genes result in biofilms with an altered mature structure but do not confer defects in growth or early biofilm formation, swimming, or twitching motility. After …
Sadb Is Required For The Transition From Reversible To Irreversible Attachment During Biofilm Formation By Pseudomonas Aeruginosa Pa14, Nicky C. Caiazza, George A. O'Toole
Sadb Is Required For The Transition From Reversible To Irreversible Attachment During Biofilm Formation By Pseudomonas Aeruginosa Pa14, Nicky C. Caiazza, George A. O'Toole
Dartmouth Scholarship
Current models of biofilm formation by Pseudomonas aeruginosa propose that (i) planktonic cells become surface associated in a monolayer, (ii) surface-associated cells form microcolonies by clonal growth and/or aggregation, (iii) microcolonies transition to a mature biofilm comprised of exopolysaccharide-encased macrocolonies, and (iv) cells exit the mature biofilm and reenter the planktonic state. Here we report a new class of P. aeruginosa biofilm mutant that defines the transition from reversible to irreversible attachment and is thus required for monolayer formation. The transposon insertion carried by the sadB199 mutant was mapped to open reading frame PA5346 of P. aeruginosa PA14 and encodes …
The Virulence Activator Apha Links Quorum Sensing To Pathogenesis And Physiology In Vibrio Cholerae By Repressing The Expression Of A Penicillin Amidase Gene On The Small Chromosome, Gabriela Kovacikova, Wei Lin, Karen Skorupski
The Virulence Activator Apha Links Quorum Sensing To Pathogenesis And Physiology In Vibrio Cholerae By Repressing The Expression Of A Penicillin Amidase Gene On The Small Chromosome, Gabriela Kovacikova, Wei Lin, Karen Skorupski
Dartmouth Scholarship
Activation of the tcpPH promoter on the Vibrio pathogenicity island by AphA and AphB initiates the Vibrio cholerae virulence cascade and is regulated by quorum sensing through the repressive action of HapR on aphA expression. To further understand how the chromosomally encoded AphA protein activates tcpPH expression, site-directed mutagenesis was used to identify the base pairs critical for AphA binding and transcriptional activation. This analysis revealed a region of partial dyad symmetry, TATGCA-N6-TNCNNA, that is important for both of these activities. Searching the V. cholerae genome for this binding site permitted the identification of a second one upstream of a …
Saru, A Sara Homolog, Is Repressed By Sart And Regulates Virulence Genes In Staphylococcus Aureus, Adhar C. Manna, Ambrose L. Cheung
Saru, A Sara Homolog, Is Repressed By Sart And Regulates Virulence Genes In Staphylococcus Aureus, Adhar C. Manna, Ambrose L. Cheung
Dartmouth Scholarship
In searching the Staphylococcus aureus genome, we previously identified sarT, a homolog of sarA, which encodes a repressor for alpha-hemolysin synthesis. Adjacent but transcribed divergently to sarT is sarU, which encodes a 247-residue polypeptide, almost twice the length of SarA. Sequence alignment disclosed that SarU, like SarS, which is another SarA homolog, could be envisioned as a molecule with two halves, with each half being homologous to SarA. SarU, as a member of the SarA family proteins, disclosed conservation of basic residues within the helix-turn-helix motif and within the beta hairpin loop, two putative DNA binding domains within this protein …
Transcriptional Interference By Independently Regulated Genes Occurs In Any Relative Arrangement Of The Genes And Is Influenced By Chromosomal Integration Position, Susan K. Eszterhas, Eric E. Bouhassira, David I. K. Martin, Steven Fiering
Transcriptional Interference By Independently Regulated Genes Occurs In Any Relative Arrangement Of The Genes And Is Influenced By Chromosomal Integration Position, Susan K. Eszterhas, Eric E. Bouhassira, David I. K. Martin, Steven Fiering
Dartmouth Scholarship
Transcriptional interference is the influence, generally suppressive, of one active transcriptional unit on another unit linked in cis. Its wide occurrence in experimental systems suggests that it may also influence transcription in many loci, but little is known about its precise nature or underlying mechanisms. Here we report a study of the interaction of two nearly identical transcription units juxtaposed in various arrangements. Each reporter gene in the constructs has its own promoter and enhancer and a strong polyadenylation signal. We used recombinase-mediated cassette exchange (RMCE) to insert the constructs into previously tagged genomic sites in cultured cells. This …
Evaluation Of A Tetracycline-Inducible Promoter In Staphylococcus Aureus In Vitro And In Vivo And Its Application In Demonstrating The Role Of Sigb In Microcolony Formation, B. T. Bateman, N. P. Donegan, T. M. Jarry, M. Palma
Evaluation Of A Tetracycline-Inducible Promoter In Staphylococcus Aureus In Vitro And In Vivo And Its Application In Demonstrating The Role Of Sigb In Microcolony Formation, B. T. Bateman, N. P. Donegan, T. M. Jarry, M. Palma
Dartmouth Scholarship
An inducible promoter system provides a powerful tool for studying the genetic basis for virulence. A variety of inducible systems have been used in other organisms, including pXyl-xylR-inducible promoter, the pSpac-lacI system, and the arabinose-inducible PBAD promoter, but each of these systems has limitations in its application to Staphylococcus aureus. In this study, we demonstrated the efficacy of a tetracycline-inducible promoter system in inducing gene expression in S. aureus in vitro and inside epithelial cells as well as in an animal model of infection. Using the xyl/tetO promoter::gfpuvr fusion carried on a shuttle …
Sart, A Repressor Of Α-Hemolysin In Staphylococcus Aureus, Katherine A. Schmidt, Adhar C. Manna, Steven Gill, Ambrose L. Cheung
Sart, A Repressor Of Α-Hemolysin In Staphylococcus Aureus, Katherine A. Schmidt, Adhar C. Manna, Steven Gill, Ambrose L. Cheung
Dartmouth Scholarship
In searching the Staphylococcus aureus genome, we found several homologs to SarA. One of these genes, sarT, codes for a basic protein with 118 residues and a predicted molecular size of 16,096 Da. Northern blot analysis revealed that the expression of sarT was repressed by sarA and agr. An insertion sarT mutant generated in S. aureus RN6390 and 8325-4 backgrounds revealed minimal effect on the expression of sarR and sarA. The RNAIII level was notably increased in the sarT mutant, particularly in postexponential-phase cells, while the augmentative effect on RNAII was less. SarT repressed the expression of alpha-hemolysin, as determined …
Sars, A Sara Homolog Repressible By Agr, Is An Activator Of Protein A Synthesis In Staphylococcus Aureus, Ambrose L. Cheung, Katherine Schmidt, Brian Bateman, Adhar C. Manna
Sars, A Sara Homolog Repressible By Agr, Is An Activator Of Protein A Synthesis In Staphylococcus Aureus, Ambrose L. Cheung, Katherine Schmidt, Brian Bateman, Adhar C. Manna
Dartmouth Scholarship
The expression of protein A (spa) is repressed by global regulatory loci sarA and agr. Although SarA may directly bind to the spa promoter to downregulate spa expression, the mechanism by which agr represses spa expression is not clearly understood. In searching for SarA homologs in the partially released genome, we found a SarA homolog, encoding a 250-amino-acid protein designated SarS, upstream of the spa gene. The expression of sarS was almost undetectable in parental strain RN6390 but was highly expressed in agr and sarA mutants, strains normally expressing high level of protein A. Interestingly, protein A …
Characterization Of Sarr, A Modulator Of Sar Expression In Staphylococcus Aureus, Adhar Manna, Ambrose L. Cheung
Characterization Of Sarr, A Modulator Of Sar Expression In Staphylococcus Aureus, Adhar Manna, Ambrose L. Cheung
Dartmouth Scholarship
The expression of virulence determinants in Staphylococcus aureus is controlled by global regulatory loci (e.g., sar and agr). The sar locus is composed of three overlapping transcripts (sar P1, P3, and P2 transcripts from P1, P3, and P2 promoters, respectively), all encoding the 372-bp sarA gene. The level of SarA, the major regulatory protein, is partially controlled by the differential activation of sar promoters. We previously partially purified a ∼12 kDa protein with a DNA-specific column
A Phorbol Ester Response Element Within The Human T-Cell Receptor Beta-Chain Enhancer., Haydn M. Prosser, David Wotton, Anne Gegonne, Jacques Ghysdael, Shuwen Wang, Nancy A. Speck, Michael J. Owen
A Phorbol Ester Response Element Within The Human T-Cell Receptor Beta-Chain Enhancer., Haydn M. Prosser, David Wotton, Anne Gegonne, Jacques Ghysdael, Shuwen Wang, Nancy A. Speck, Michael J. Owen
Dartmouth Scholarship
The activity of the T-cell receptor beta-chain gene enhancer is increased by activators of the protein kinase C pathway during T-cell activation. Analysis of mutant enhancer constructs identified two elements, beta E2 and beta E3, conferring phorbol ester inducibility. Multimerized beta E2 acted in isolation as a phorbol ester-responsive element. Both beta E2 and beta E3, which contain a consensus Ets-binding site, were shown to bind directly to the product of the c-ets-1 protooncogene. Both regions also bound a second factor, core-binding factor. Mutation of the beta E2 Ets site abolished the inducibility of the beta E2 multimer. beta E2 …
Characterization Of The Formate (For) Locus, Which Encodes The Cytosolic Serine Hydroxymethyltransferase Of Neurospora Crassa., C. Robertson Mcclung, Cynthia R. Davis, Karen M. Page, Sylvia A. Denome
Characterization Of The Formate (For) Locus, Which Encodes The Cytosolic Serine Hydroxymethyltransferase Of Neurospora Crassa., C. Robertson Mcclung, Cynthia R. Davis, Karen M. Page, Sylvia A. Denome
Dartmouth Scholarship
Serine hydroxymethyltransferase (SHMT) occupies a central position in one-carbon (C1) metabolism, catalyzing the reaction of serine and tetrahydrofolate to yield glycine and 5,10-methylenetetrahydrofolate. Methylenetetrahydrofolate serves as a donor of C1 units for the synthesis of numerous compounds, including purines, thymidylate, lipids, and methionine. We provide evidence that the formate (for) locus of Neurospora crassa encodes cytosolic SHMT. The for+ gene was localized to a 2.8-kb BglII fragment by complementation (restoration to formate-independent growth) of a strain carrying a recessive for allele, which confers a growth requirement for formate. The for+ gene encodes a polypeptide of 479 amino acids which shows …