Other Biochemistry, Biophysics, and Structural Biology Commons^™

Hare-Mediated Endocytosis Of Hyaluronan And Heparin Is Targeted By Different Subsets Of Three Endocytic Motifs, Madhu S. Pandey, Edward N. Harris, Paul H. Weigel

Department of Biochemistry: Faculty Publications

The hyaluronan (HA) receptor for endocytosis (HARE) is a multifunctional recycling clearance receptor for 14 different ligands, including HA and heparin (Hep), which bind to discrete nonoverlapping sites. Four different functional endocytic motifs (M) in the cytoplasmic domain (CD) target coated pit mediated uptake: (YSYFRI²⁴⁸⁵ (M1), FQHF²⁴⁹⁵ (M2), NPLY²⁵¹⁹ (M3), and DPF²⁵³⁴ (M4)). We previously found (Pandey et al. J. Biol. Chem. 283, 21453, 2008) that M1, M2, and M3 mediate endocytosis of HA. Here we assessed the ability of HARE variants with a single-motif deletion …

Tissue-Specific Splice Variants Of Hare/Stabilin-2 Are Expressed In Bone Marrow, Lymph Node, And Spleen, Amanda K. Hare, Edward N. Harris

Department of Biochemistry: Faculty Publications

The hyaluronan receptor for endocytosis (HARE), or Stabilin-2, is the mammalian endocytic clearance receptor for HA, heparin, advanced glycation end-products, acetylated and oxidized low-density lipoproteins and collagen N-terminal propeptides. This large 2551 amino acid receptor is encoded by a gene that covers over 180 kbp on human chromosome 12 and is predicted to be composed of 69 exons. Due to the expression profile of this gene and the number of exons it contains, we hypothesized that splice variants of stab2 are encoded in these tissues. In addition, a correlation between alternative splice variants and cancer progression has been shown in …

Overaccumulation Of Γ-Glutamylcysteine In A Jasmonate-Hypersensitive Arabidopsis Mutant Causes Jasmonate-Dependent Growth Inhibition, Hsin-Ho Wei, Martha Rowe, Jean-Jack M. Riethoven, Ryan Grove, Jiri Adamec, Yusuke Jikumaru, Paul E. Staswick

Department of Biochemistry: Faculty Publications

Glutathione (GSH) is essential for many aspects of plant biology and is associated with jasmonate signaling in stress responses. We characterized an Arabidopsis (Arabidopsis thaliana) jasmonate-hypersensitive mutant (jah2) with seedling root growth 100-fold more sensitive to inhibition by the hormone jasmonyl-isoleucine than the wild type. Genetic mapping and genome sequencing determined that the mutation is in intron 6 of GLUTATHIONE SYNTHETASE2, encoding the enzyme that converts γ-glutamylcysteine (γ-EC) to GSH. The level of GSH in jah2 was 71% of the wild type, while the phytoalexin-deficient2-1 (pad2-1) mutant, defective in GSH1 and …

Overexpression Of Alpha-Synuclein At Non-Toxic Levels Increases Dopaminergic Cell Death Induced By Copper Exposure Via Modulation Of Protein Degradation Pathways, Annadurai Anandhan, Humberto Rodriguez-Rocha, Iryna Bohovych, Amy M. Griggs, Laura Zavala-Flores, Elsa M. Reyes-Reyes, Javier Seravalli, Lia A. Stanciu, Jaekwon Lee, Jean-Christophe Rochet, Oleh Khalimonchuk, Rodrigo Franco

Department of Biochemistry: Faculty Publications

Gene multiplications or point mutations in alpha (α)-synuclein are associated with familial and sporadic Parkinson’s disease (PD). An increase in copper (Cu) levels has been reported in the cerebrospinal fluid and blood of PD patients, while occupational exposure to Cu has been suggested to augment the risk to develop PD. We aimed to elucidate the mechanisms by which α-synuclein and Cu regulate dopaminergic cell death. Short-term overexpression of WT or A53T α-synuclein had no toxic effect in human dopaminergic cells and primary midbrain cultures, but it exerted a synergistic effect on Cu-induced cell death. Cell death induced by Cu was …

Rerouting Cellular Electron Flux To Increase The Rate Of Biological Methane Production, Jennie L. Catlett, Alicia M. Ortiz, Nicole R. Baun

Department of Biochemistry: Faculty Publications

Methanogens are anaerobic archaea that grow by producing methane, a gas that is both an efficient renewable fuel and a potent greenhouse gas. We observed that overexpression of the cytoplasmic heterodisulfide reductase enzyme HdrABC increased the rate of methane production from methanol by 30% without affecting the growth rate relative to the parent strain. Hdr enzymes are essential in all known methane-producing archaea. They function as the terminal oxidases in the methanogen electron transport system by reducing the coenzymeM(2-mercaptoethane sulfonate) and coenzyme B (7-mercaptoheptanoylthreonine sulfonate) heterodisulfide, CoM-S-S-CoB, to regenerate the thiol-coenzymes for reuse. In Methanosarcina acetivorans, HdrABC expression caused …

Role Of Micrornas In Alcohol-Induced Multi-Organ Injury, Sathish Kumar Natarajan, Joseph M. Pachunka, Justin L. Mott

Department of Biochemistry: Faculty Publications

Alcohol consumption and its abuse is a major health problem resulting in significant healthcare cost in the United States. Chronic alcoholism results in damage to most of the vital organs in the human body. Among the alcohol-induced injuries, alcoholic liver disease is one of the most prevalent in the United States. Remarkably, ethanol alters expression of a wide variety of microRNAs that can regulate alcohol-induced complications or dysfunctions. In this review, we will discuss the role of microRNAs in alcoholic pancreatitis, alcohol-induced liver damage, intestinal epithelial barrier dysfunction, and brain damage including altered hippocampus structure and function, and neuronal loss, …

Salivary Gland Structure Of Ctenarytaina Eucalypti (Maskell, 1890) (Hemiptera) And Phloem Exudate In Eucalyptus Globulus Labillardière, 1799 (Myrtaceae), Anamika Sharma, Soundararajan Madhavan, Anantanarayanan Raman, Gary S. Taylor, Murray J. Fletcher

Department of Biochemistry: Faculty Publications

The structure of the salivary glands of the free-living aphalarid Ctenarytaina eucalypti, which infests multiple species of Eucalyptus in Australasia and has been introduced into many other regions of the world, is described and illustrated. The principal salivary gland is multilobed whereas the accessory gland is tubular. 1-D electrophoresis revealed proteins of approximately 58 and 64 kDa in the salivary gland extracts and proteins of similar molecular weights in the extracted plant exudates, including phloem, from infested leaves and tender shoots of E. globulus. Proteins that could fall within this range include, but are not limited to, glucosemethanol- …

Sestrin2, A Regulator Of Thermogenesis And Mitohormesis In Brown Adipose Tissue, Seung-Hyun Ro, Ian Semple, Allison Ho, Hwan-Woo Park, Jun Hee Lee

Department of Biochemistry: Faculty Publications

Sestrin2 is a stress-inducible protein that functions as an antioxidant and inhibitor of mTOR complex 1. In a recent study, we found that Sestrin2 overexpression in brown adipocytes interfered with normal metabolism by reducing mitochondrial respiration through the suppression of uncoupling protein 1 (UCP1) expression. The metabolic effects of Sestrin2 in brown adipocytes were dependent on its antioxidant activity, and chemical antioxidants produced similar effects in inhibiting UCP1-dependent thermogenesis. These observations suggest that low levels of reactive oxygen species (ROS) in brown adipocytes can actually be beneficial and necessary for proper metabolic homeostasis. In addition, considering that Sestrins are ROS …

Triacylglycerol Synthesis During Nitrogen Stress Involves The Prokaryotic Lipid Synthesis Pathway And Acyl Chain Remodeling In The Microalgae Coccomyxa Subellipsoidea, James W. Allen, Concetta C. Dirusso, Paul N. Black

Department of Biochemistry: Faculty Publications

Triglyceride (TAG) synthesis during nitrogen starvation and recovery was addressed using Coccomyxa subellipsoidea by analyzing acylchain composition and redistribution using a bioreactor-controlled time course. Galactolipids, phospholipids and TAGs were profiled using liquid chromatography tandem mass spectroscopy (LC–MS/MS). TAG levels increased linearly through 10 days of N starvation to a final concentration of 12.6% dry weight (DW), while chloroplast membrane lipids decreased from 5% to 1.5% DW. The relative quantities of TAG molecular species, differing in acyl chain length and glycerol backbone position, remained unchanged from 3 to 10 days of N starvation. Six TAG species comprised approximately half the TAG …

Phenotypic Screening Identifies Brefeldin A/Ascotoxin As An Inducer Of Lipid Storage In The Algae Chlamydomonas Reinhardtii, Nishikant Wase, Boqiang Tu, Paul N. Black, Concetta C. Dirusso

Department of Biochemistry: Faculty Publications

The use of microalgae as a biofuel feedstock is highly desired, but current methods to induce lipid accumulation cause severe stress responses that limit biomass and, thus oil yield. To address these issues, a high throughput screening (HTS) method was devised to identify chemical inducers of growth and lipid accumulation. Optimization was performed to determine the most effective cell density, DMSO and Nile Red (NR) concentrations to monitor growth and lipid accumulation. The method was tested using 1717 compounds from National Cancer Institute (NCI) Diversity Set III and Natural Products Set II in Chlamydomonas reinhardtii. Cells were inoculated at …

Correction For Sandai Et Al., The Evolutionary Rewiring Of Ubiquitination Targets Has Reprogrammed The Regulation Of Carbon Assimilation In The Pathogenic Yeast Candida Albicans, Doblin Sandai, Zhikang Yin, Laura Selway, David Stead, Janet Walker, Michelle D. Leach, Iryna Bohovych, Iuliana V. Ene, Stavroula Kastora, Susan Budge, Carol A. Munro, Frank C. Odds, Neil A.R. Gow, Alistair J.P. Brown

Department of Biochemistry: Faculty Publications

No abstract provided.

Some Of The Most Interesting Casp11 Targets Through The Eyes Of Their Authors, Andriy Kryshtafovych, John Moult, Arnaud Basle, Alex Burgin, Timonthy K. Craig, Robert A. Edwards, Deborah Fass, Marcus D. Hartmann, Mateusz Korycinski, Richard J. Lewis, Donald Lorimer, Andrei N. Lupas, Janet Newman, Thomas S. Peat, Kurt H. Piepenbrink, Janani Prahlad, Mark J. Van Raaij, Forest Rohwer, Anca M. Segall, Victor Seguritan, Eric J. Sundberg, Abhimanyu K. Singh, Mark A. Wilson, Torsten Schwede

Department of Biochemistry: Faculty Publications

The Critical Assessment of protein Structure Prediction (CASP) experiment would not have been possible without the prediction targets provided by the experimental structural biology community. In this article, selected crystallographers providing targets for the CASP11 experiment discuss the functional and biological significance of the target proteins, highlight their most interesting structural features, and assess whether these features were correctly reproduced in the predictions submitted to CASP11.

Advances In Hyaluronan Biology: Signaling, Regulation, And Disease Mechanisms, Melanie A. Simpson, Carol De La Motte, Larry S. Sherman, Paul H. Weigel

Department of Biochemistry: Faculty Publications

Hyaluronan is an extracellular glycosaminoglycan polymer consisting of linear disaccharide units containing alternating glucuronate and N-acetylglucosamine.Many cell types make hyaluronan, which unlike most other macromolecules is assembled at the plasmamembrane and concurrently translocated through the hyaluronan synthase enzyme. The normal function of large hyaluronan polymers (>1MDa) in tissue cushioning, hydration, and lubrication is well established. The aberrant accumulation and degradation of hyaluronan and the receptor-mediated signaling of smaller hyaluronan fragments have also been extensively implicated in a variety of pathological states including inflammation and cancer. More recently, the discovery that hyaluronan can either be a structural matrix component or …

Janus-Faced Sestrin2 Controls Ros And Mtor Signalling Through Two Separate Functional Domains, Hanseong Kim, Sojin An, Seung-Hyun Ro, Filipa Teixeira, Gyeong Jin Park, Cheal Kim, Chun-Seok Cho, Jeong-Sig Kim, Ursula Jakob, Jun Hee Lee, Uhn-Soo Cho

Department of Biochemistry: Faculty Publications

Sestrins are stress-inducible metabolic regulators with two seemingly unrelated but physiologically important functions: reduction of reactive oxygen species (ROS) and inhibition of the mechanistic target of rapamycin complex 1 (mTORC1). How Sestrins fulfil this dual role has remained elusive so far. Here we report the crystal structure of human Sestrin2 (hSesn2), and show that hSesn2 is twofold pseudo-symmetric with two globular subdomains, which are structurally similar but functionally distinct from each other. While the N-terminal domain (Sesn-A) reduces alkylhydroperoxide radicals through its helix–turn–helix oxidoreductase motif, the C-terminal domain (Sesn-C) modified this motif to accommodate physical interaction with GATOR2 and subsequent …

Genetic Variation In Miscanthus X Giganteus And The Importance Of Estimating Genetic Distance Thresholds For Differentiating Clones, Katarzyna Glowacka, Lindsay V. Clark, Shivani Adhikari, Junhua Peng, J. Ryan Stewart, Aya Nishiwaki, Toshihiko Yamada, Uffe Jorgensen, Trevor R. Hodkinson, Justin Gifford, John A. Juvik, Erik J. Sacks

Department of Biochemistry: Faculty Publications

Miscanthus x giganteus (Mxg) is an important bioenergy feedstock crop, however, genetic diversity among legacy cultivars may be severely constrained. Only one introduction from Japan to Denmark of this sterile, triploid, vegetatively propagated crop was recorded in the 1930s. We sought to determine if the Mxg cultivars in North America were all synonyms, and if they were derived from the European introduction. We used 64 nuclear and five chloroplast simple sequence repeat (SSR) markers to estimate genetic similarity for 27 Mxg accessions from North America, and compared them with six accessions from Europe, including the species’ type-specimen. A subset of …

Hyaluronidase Hyal1 Increases Tumor Cell Proliferation And Motility Through Accelerated Vesicle Trafficking, Caitlin O Mcatee, Abigail R. Berkebile, Christian Elowsky, Teresa Fangman, Joseph J. Barycki, James K. Wahl Iii, Oleh Khalimonchuk, Naava Naslavsky, Steve Caplan, Melanie A. Simpson

Department of Biochemistry: Faculty Publications

Background: Hyal1 is a turnover enzyme for hyaluronan that accelerates metastatic cancer by increasing cell motility.

Results: Hyal1-overexpressing cells have a higher rate of endocytosis that impacts cargo internalization and recycling.

Conclusion: The higher rate of vesicle trafficking increases motility receptor function and nutrient uptake.

Significance: This novel mechanism implicates Hyal1 trafficking in multiple signaling events during tumor progression.

Cytosolic Fe-S Cluster Protein Maturation And Iron Regulation Are Independent Of The Mitochondrial Erv1/Mia40 Import System, Hatice K. Ozer, Adrienne C. Dlouhy, Jeremy D. Thornton, Jingjing Hu, Yilin Liu, Joseph J. Barycki, Janneke Balk, Caryn E. Outten

Department of Biochemistry: Faculty Publications

Background: The mitochondrial sulfhydryl oxidase Erv1 is implicated in cytosolic iron-sulfur protein maturation and iron regulation.

Results: An erv1 yeast strain used in previous iron metabolism studies is glutathione-deficient, and erv1/mia40 mutants with sufficient glutathione do not exhibit iron-related defects.

Conclusion: Iron homeostasis is independent of Erv1/Mia40 function. Significance: The unexplained role of Erv1 in yeast iron metabolism is resolved.

Metalloprotease Oma1 Fine-Tunes Mitochondrial Bioenergetic Function And Respiratory Supercomplex Stability, Iryna Bohovych, Mario R. Fernandez, Jennifer J. Rahn, Krista D. Stackley, Jennifer E. Bestman, Annadurai Anandhan, Rodrigo Franco, Steven M. Claypool, Robert E. Lewis, Sherine S.L. Chan, Oleh Khalimonchuk

Department of Biochemistry: Faculty Publications

Mitochondria are involved in key cellular functions including energy production, metabolic homeostasis, and apoptosis. Normal mitochondrial function is preserved by several interrelated mechanisms. One mechanism – intramitochondrial quality control (IMQC) – is represented by conserved proteases distributed across mitochondrial compartments. Many aspects and physiological roles of IMQC components remain unclear. Here, we show that the IMQC protease Oma₁ is required for the stability of the respiratory supercomplexes and thus balanced and tunable bioenergetic function. Loss of Oma1 activity leads to a specific destabilization of respiratory supercomplexes and consequently to unbalanced respiration and progressive respiratory decline in yeast. Similarly, experiments …

Connecting Proline Metabolism And Signaling Pathways In Plant Senescence, Lu Zhang, Donald F. Becker

Department of Biochemistry: Faculty Publications

The amino acid proline has a unique biological role in stress adaptation. Proline metabolism is manipulated under stress by multiple and complex regulatory pathways and can profoundly influence cell death and survival in microorganisms, plants, and animals. Though the effects of proline are mediated by diverse signaling pathways, a common theme appears to be the generation of reactive oxygen species (ROS) due to proline oxidation being coupled to the respiratory electron transport chain. Considerable research has been devoted to understand how plants exploit proline metabolism in response to abiotic and biotic stress. Here, we review potential mechanisms by which proline …

Secretoglobin And Transferrin Expression In Bronchoalveolar Lavage Fluid Of Horses With Chronic Respiratory Disease, M. Miskovic Feutz, Laurent Couetil, C.P. Riley, X. Zhang, J. Adamec, R.E. Raskin

Department of Biochemistry: Faculty Publications

Background: Lower expression of secretoglobin and transferrin has been found in the bronchoalveolar lavage fluid (BALF) of a small number of horses with experimentally induced signs of recurrent airway obstruction (RAO) compared to healthy controls.

Hypothesis/Objectives: Secretoglobin and transferrin BALF expression will be similarly decreased in horses with naturally occurring clinical signs of RAO and in horses with experimentally induced clinical signs of RAO as compared to healthy controls and intermediate in horses with inflammatory airway disease (IAD).

Animals: Recurrent airway obstruction-affected and control horses were subjected to an experimental hay exposure trial to induce signs of RAO. Client-owned horses …

Expression Analysis Of A Glucose Oxidase Transgene In Tobacco, Jordan Burt

Honors Theses

Glucose oxidase (GOX) is an enzyme in plants that catalyzes the oxidation of glucose to hydrogen peroxide and Glucono delta-lactone[5]. We have expressed GOX under the control of an estrogen inducible system, XVE, to analyze the gene's expression under this system compared to a system using the 35s system. The 35s system contains a promoter that constitutively turns on the GOX gene in the Nicotiana tabacum plant which causes the gene to always be turned on. Leaf disc assays were performed with discs from 35s, XVE, and also wild type plants (not containing the GOX gene) in order to extract …

Transfer Rna Comes Of Age, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

"The year the journal RNA was founded was slated by some in scientific publishing to be the year that one particular type of RNA's run in the spotlight would end. In 1995 I had recently started as a post-doc with Dieter Söll at Yale when he came into the lab to solemnly inform us all that an editor at a certain (S)cience journal had just told him “we won't be publishing any more tRNA papers.” For a post-doc who had migrated across the Atlantic for the sole purpose of furthering his career by working on tRNA this was not great …

Effect Of Hydrogen Peroxide On The Biosynthesis Of Heme And Proteins: Potential Implications For The Partitioning Of Glu-TrnaGlu Between These Pathways, Carolina Farah, Gloria Levicán, Michael Ibba, Omar Orellana

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Glutamyl-tRNA (Glu-tRNA^Glu) is the common substrate for both protein translation and heme biosynthesis via the C5 pathway. Under normal conditions, an adequate supply of this aminoacyl-tRNA is available to both pathways. However, under certain circumstances, Glu-tRNA^Glu can become scarce, resulting in competition between the two pathways for this aminoacyl-tRNA. In Acidithiobacillus ferrooxidans, glutamyl-tRNA synthetase 1 (GluRS1) is the main enzyme that synthesizes Glu-tRNA^Glu. Previous studies have shown that GluRS1 is inactivated in vitro by hydrogen peroxide (H₂O₂). This raises the question as to whether H₂O₂ negatively affects …

Design, Assessment, And In Vivo Evaluation Of A Computational Model Illustrating The Role Of Cav1 In Cd4+ T-Lymphocytes, Brittany D. Conroy, Tyler A. Herek, Timonthy D. Shew, Matthew Latner, Joshua J. Larson, Laura Allen, Paul H. Davis, Tomáš Helikar, Christine E. Cutucache

Department of Biochemistry: Faculty Publications

Caveolin-1 (CAV1) is a vital scaffold protein heterogeneously expressed in both healthy and malignant tissue. We focus on the role of CAV1 when overexpressed in T-cell leukemia. Previously, we have shown that CAV1 is involved in cell-to-cell communication, cellular proliferation, and immune synapse formation; however, the molecular mechanisms have not been elucidated.We hypothesize that the role of CAV1 in immune synapse formation contributes to immune regulation during leukemic progression, thereby warranting studies of the role of CAV1 in CD4⁺ T-cells in relation to antigen-presenting cells. To address this need, we developed a computational model of a CD4⁺ immune …

Computer Simulations Of Enzymes, Jianzhuang Yao

Doctoral Dissertations

Enzymes are important catalysts in living systems, and understanding catalytic mechanisms of enzymes is an important task for modern biophysics and biochemistry. Computer simulations have emerged as very useful tools for understanding how enzymes work. In this dissertation, QM/MM MD simulations were applied to study the catalytic mechanisms of several enzymes, including sedolisin, S-adenosyl-L-methionine (AdoMet)-dependent methyltransferases, and salicylic acid binding protein 2. For sedolisin, we focus on the acylation and deacylation reactions catalyzed by the enzymes. We proposed a general acid/base mechanism involving the Glu/Asp residues at the active site. MD and QM/MM free energy simulations on pro-kumamolisin show that …

Comparative Genomics Of Microbial Chemoreceptor Sequence, Structure, And Function, Aaron Daniel Fleetwood

Doctoral Dissertations

Microbial chemotaxis receptors (chemoreceptors) are complex proteins that sense the external environment and signal for flagella-mediated motility, serving as the GPS of the cell. In order to sense a myriad of physicochemical signals and adapt to diverse environmental niches, sensory regions of chemoreceptors are frenetically duplicated, mutated, or lost. Conversely, the chemoreceptor signaling region is a highly conserved protein domain. Extreme conservation of this domain is necessary because it determines very specific helical secondary, tertiary, and quaternary structures of the protein while simultaneously choreographing a network of interactions with the adaptor protein CheW and the histidine kinase CheA. This dichotomous …

Numerical Simulations Of In Vitro Nanoparticle Toxicity – The Case Of Poly(Amido Amine) Dendrimers., Marcus Maher, Pratap Naha, Sourav Prasanna Mukherjee, Hugh Byrne

Articles

A phenomenological rate equation model is constructed to numerically simulate nanoparticle uptake and subsequent cellular response. Polyamidoamine dendrimers (generations 4-6) are modelled and the temporal evolution of the intracellular cascade of; increased levels of reactive oxygen species, intracellular antioxidant species, caspase activation, mitochondrial membrane potential decay, tumour necrosis factor and interleukin generation is simulated, based on experimental observations.

The dose and generation dependence of several of these response factors are seen to well represent experimental observations at a range of time points. The model indicates that variations between responses of different cell-lines, including murine macrophages, human keratinocytes and colon cells, …

Overexpression Of Patatin-Related Phospholipase Aiiiβ Altered The Content And Composition Of Sphingolipids In Arabidopsis, Maoyin Li, Jennifer E. Markham, Xuemin Wang

Department of Biochemistry: Faculty Publications

In plants, fatty acids are primarily synthesized in plastids and then transported to the endoplasmic reticulum (ER) for synthesis of most of the complex membrane lipids, including glycerolipids and sphingolipids. The first step of sphingolipid synthesis, which uses a fatty acid and a serine as substrates, is critical for sphingolipid homeostasis; its disruption leads to an altered plant growth. Phospholipase As have been implicated in the trafficking of fatty acids from plastids to the ER. Previously, we found that overexpression of a patatin-related phospholipase, pPLAIIIβ, resulted in a smaller plant size and altered anisotropic cell expansion. Here, we determined the …

The Non-Canonical Hydroxylase Structure Of Yfcm Reveals A Metal Ion-Coordination Motif Required For Ef-P Hydroxylation, Kan Kobayashi, Assaf Katz, Andrei Rajkovic, Ryohei Ishii, Owen E. Branson, Michael A. Freitas, Ryuichiro Ishitani, Michael Ibba, Osamu Nureki

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

EF-P is a bacterial tRNA-mimic protein, which accelerates the ribosome-catalyzed polymerization of poly-prolines. In Escherichia coli, EF-P is post-translationally modified on a conserved lysine residue. The post-translational modification is performed in a two-step reaction involving the addition of a β-lysine moiety and the subsequent hydroxylation, catalyzed by PoxA and YfcM, respectively. The β-lysine moiety was previously shown to enhance the rate of poly-proline synthesis, but the role of the hydroxylation is poorly understood. We solved the crystal structure of YfcM and performed functional analyses to determine the hydroxylation mechanism. In addition, YfcM appears to be structurally distinct from any …

Mistranslation Of The Genetic Code, Adil Moghal, Kyle Mohler, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

During mRNA decoding at the ribosome, deviations from stringent codon identity, or “mistranslation,” are generally deleterious and infrequent. Observations of organisms that decode some codons ambiguously, and the discovery of a compensatory increase in mistranslation frequency to combat environmental stress have changed the way we view “errors” in decoding. Modern tools for the study of the frequency and phenotypic effects of mistranslation can provide quantitative and sensitive measurements of decoding errors that were previously inaccessible. Mistranslation with non‐protein amino acids, in particular, is an enticing prospect for new drug therapies and the study of molecular evolution.