Biochemistry, Biophysics, and Structural Biology Commons^™

Genome, Functional Gene Annotation, And Nuclear Transformation Of The Heterokont Oleaginous Alga Nannochloropsis Oceanica Ccmp1779, Astrid Vieler, Guangxi Wu, Chia-Hong Tsai, Blair Bullard, Adam J. Cornish, Christopher Harvey, Ida-Barbara Reca, Chelsea Thornburg, Rujira Achawanantakun, Christopher J. Buehl, Michael S. Campbell, David Cavalier, Kevin L. Childs, Teresa J. Clark, Rahul Deshpande, Erika Erickson, Ann Armenia Ferguson, Witawas Handee, Que Kong, Xiaobo Li, Bensheng Liu, Steven Lundback, Cheng Peng, Rebecca Roston, Michigan State University, Jeffrey P. Simpson, Allan Terbush, Jaruswan Warakanont, Simone Zäuner, Eva M. Farre, Eric L. Hegg, Ning Jiang, Min-Hao Kuo, Yan Lu, Krishna K. Niyogi, John Ohlrogge, Katherine W. Osteryoung, Yair Shachar-Hill, Barbara B. Sears, Yanni Sun, Hideki Takahashi, Mark Yandell, Shin-Han Shiu, Christoph Benning

Department of Biochemistry: Faculty Publications

Unicellular marine algae have promise for providing sustainable and scalable biofuel feedstocks, although no single species has emerged as a preferred organism. Moreover, adequate molecular and genetic resources prerequisite for the rational engineering of marine algal feedstocks are lacking for most candidate species. Heterokonts of the genus Nannochloropsis naturally have high cellular oil content and are already in use for industrial production of high-value lipid products. First success in applying reverse genetics by targeted gene replacement makes Nannochloropsis oceanica an attractive model to investigate the cell and molecular biology and biochemistry of this fascinating organism group. Here we present the …

Cellular Responses Of Candida Albicans To Phagocytosis And The Extracellular Activities Of Neutrophils Are Critical To Counteract Carbohydrate Starvation, Oxidative And Nitrosative Stress, Pedro Miramón, Christine Dunker, Hanna Windecker, Iryna Bohovych, Alistair J.P. Brown, Oliver Kurzai, Bernhard Hube

Department of Biochemistry: Faculty Publications

Neutrophils are key players during Candida albicans infection. However, the relative contributions of neutrophil activities to fungal clearance and the relative importance of the fungal responses that counteract these activities remain unclear. We studied the contributions of the intra- and extracellular antifungal activities of human neutrophils using diagnostic Green Fluorescent Protein (GFP)-marked C. albicans strains. We found that a carbohydrate starvation response, as indicated by upregulation of glyoxylate cycle genes, was only induced upon phagocytosis of the fungus. Similarly, the nitrosative stress response was only observed in internalised fungal cells. In contrast, the response to oxidative stress was observed in …

Small But Crucial: The Novel Small Heat Shock Protein Hsp21 Mediates Stress Adaptation And Virulence In Candida Albicans, Francois L. Mayer, Duncan Wilson, Ilse D. Jacobsen, Pedro Miramón, Silvia Slesiona, Iryna Bohovych, Alistair J.P. Brown, Bernhard Hube

Department of Biochemistry: Faculty Publications

Small heat shock proteins (sHsps) have multiple cellular functions. However, the biological function of sHsps in pathogenic microorganisms is largely unknown. In the present study we identified and characterized the novel sHsp Hsp21 of the human fungal pathogen Candida albicans. Using a reverse genetics approach we demonstrate the importance of Hsp21 for resistance of C. albicans to specific stresses, including thermal and oxidative stress. Furthermore, a hsp21∆/∆ mutant was defective in invasive growth and formed significantly shorter filaments compared to the wild type under various filamentinducing conditions. Although adhesion to and invasion into human-derived endothelial and oral epithelial cells …

Oligomerization Of Heme O Synthase In Cytochrome Oxidase Biogenesis Is Mediated By Cytochrome Oxidase Assembly Factor Coa2, Oleh Khalimonchuk, Hyung Kim, Talina Watts, Xochitl Perez-Martinez, Dennis R. Winge

Department of Biochemistry: Faculty Publications

The synthesis of the heme a cofactor used in cytochrome c

oxidase (CcO) is dependent on the sequential action of heme o

synthase (Cox10) and heme a synthase (Cox15). The active state of

Cox10 appears to be a homo-oligomeric complex,andformation of

this complex is dependent on the newly synthesized CcO subunit

Cox1 and the presence of an early Cox1 assembly intermediate.

Cox10 multimerization is triggered by progression of Cox1 from

the early assembly intermediate todownstreamintermediates.The

CcOassembly factor Coa2 appears important in coupling the presence

of newly synthesized Cox1 to Cox10 oligomerization. Cells

lacking Coa2 are impaired in Cox10 complex formation …

Selective Oma1 Protease-Mediated Proteolysis Of Cox1 Subunit Of Cytochrome Oxidase In Assembly Mutants, Oleh Khalimonchuk, Mi-Young Jeong, Talina Watts, Elliott Ferris, Dennis R. Winge

Department of Biochemistry: Faculty Publications

Background: Yeast lacking Coa2 are deficient in cytochrome c oxidase due to Cox1 degradation.

Results: Oma1 mediates Cox1 degradation in coa2∆ cells but not other mutants stalled in oxidase biogenesis.

Conclusion: Impaired hemylation of Cox1 in coa2∆ cells leads to misfolding and facile degradation by Oma1.

Significance: Oma1 functions in quality control of cytochrome oxidase assembly.

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

Microbes must assimilate carbon to grow and colonize their niches. Transcript profiling has suggested that Candida albicans, a major pathogen of humans, regulates its carbon assimilation in an analogous fashion to the model yeast Saccharomyces cerevisiae, repressing metabolic pathways required for the use of alterative nonpreferred carbon sources when sugars are available. However, we show that there is significant dislocation between the proteome and transcriptome in C. albicans. Glucose triggers the degradation of the ICL1 and PCK1 transcripts in C. albicans, yet isocitrate lyase (Icl1) and phosphoenolpyruvate carboxykinase (Pck1) are stable and are retained. Indeed, numerous …

Role Of Apoptosis-Inducing Factor, Proline Dehydrogenase, And Nadph Oxidase In Apoptosis And Oxidative Stress, Sathish Kumar Natarajan, Donald F. Becker

Department of Biochemistry: Faculty Publications

Flavoproteins catalyze a variety of reactions utilizing flavin mononucleotide or flavin adenine dinucleotide as cofactors. The oxidoreductase properties of flavoenzymes implicate them in redox homeostasis, oxidative stress, and various cellular processes, including programmed cell death. Here we explore three critical flavoproteins involved in apoptosis and redox signaling, ie, apoptosis-inducing factor (AIF), proline dehydrogenase, and NADPH oxidase. These proteins have diverse biochemical functions and influence apoptotic signaling by unique mechanisms. The role of AIF in apoptotic signaling is two-fold, with AIF changing intracellular location from the inner mitochondrial membrane space to the nucleus upon exposure of cells to apoptotic stimuli. In …

Late-Stage Maturation Of The Rieske Fe/S Protein: Mzm1 Stabilizes Rip1 But Does Not Facilitate Its Translocation By The Aaa Atpase Bcs1, Tie-Zhong Cui, Pamela M. Smith, Jennifer L. Fox, Oleh Khalimonchuk, Dennis R. Winge

Department of Biochemistry: Faculty Publications

The final step in the assembly of the ubiquinol-cytochrome c reductase or bc₁ complex involves the insertion of the Rieske Fe/S cluster protein, Rip1. Maturation of Rip1 occurs within the mitochondrial matrix prior to its translocation across the inner membrane (IM) in a process mediated by the Bcs1 ATPase and subsequent insertion into the bc₁ complex. Here we show that the matrix protein Mzm1 functions as a Rip1 chaperone, stabilizing Rip1 prior to the translocation step. In the absence of Mzm1, Rip1 is prone to either proteolytic degradation or temperature-induced aggregation. A series of Rip1 truncations were engineered …

Substrate Channeling In Proline Metabolism, Benjamin W. Arentson, Nikhilesh Sanyal, Donald F. Becker

Department of Biochemistry: Faculty Publications

Proline metabolism is an important pathway that has relevance in several cellular functions such as redox balance, apoptosis, and cell survival. Results from different groups have indicated that substrate channeling of proline metabolic intermediates may be a critical mechanism. One intermediate is pyrroline-5-carboxylate (P5C), which upon hydrolysis opens to glutamic semialdehyde (GSA). Recent structural and kinetic evidence indicate substrate channeling of P5C/ GSA occurs in the proline catabolic pathway between the proline dehydrogenase and P5C dehydrogenase active sites of bifunctional proline utilization A (PutA). Substrate channeling in PutA is proposed to facilitate the hydrolysis of P5C to GSA which is …

Glutaredoxin 1 Protects Dopaminergic Cells By Increased Protein Glutathionylation In Experimental Parkinson's Disease, Humberto Rodriguez-Rocha, Aracely Garcia Garcia, Laura Zavala-Flores, Sumin Li, Nandakumar Madayiputhiya, Rodrigo Franco

Department of Biochemistry: Faculty Publications

Aims: Chronic exposure to environmental toxicants, such as paraquat, has been suggested as a risk factor for Parkinson's disease (PD). Although dopaminergic cell death in PD is associated with oxidative damage, the molecular mechanisms involved remain elusive. Glutaredoxins (GRXs) utilize the reducing power of glutathione to modulate redox-dependent signaling pathways by protein glutathionylation. We aimed to determine the role of GRX1 and protein glutathionylation in dopaminergic cell death. Results: In dopaminergic cells, toxicity induced by paraquat or 6-hydroxydopamine (6-OHDA) was inhibited by GRX1 overexpression, while its knock-down sensitized cells to paraquat-induced cell death. Dopaminergic cell death was paralleled by protein …

Ergodic Sets As Cell Phenotype Of Budding Yeast Cell Cycle, Robert G. Todd, Tomáš Helikar

Department of Biochemistry: Faculty Publications

It has been suggested that irreducible sets of states in Probabilistic Boolean Networks correspond to cellular phenotype. In this study, we identify such sets of states for each phase of the budding yeast cell cycle. We find that these ‘‘ergodic sets’’ underly the cyclin activity levels during each phase of the cell cycle. Our results compare to the observations made in several laboratory experiments as well as the results of differential equation models. Dynamical studies of this model: (i) indicate that under stochastic external signals the continuous oscillating waves of cyclin activity and the opposing waves of CKIs …

The Cell Collective: Toward An Open And Collaborative Approach To Systems Biology, Tomáš Helikar, Bryan Kowal, Sean Mcclenathan, Mitchell Bruckner, Thaine Rowley, Alex Madrahimov, Ben Wicks, Manish Shrestha, Kahani Limbu, Jim A. Rogers

Department of Biochemistry: Faculty Publications

Background: Despite decades of new discoveries in biomedical research, the overwhelming complexity of cells has been a significant barrier to a fundamental understanding of how cells work as a whole. As such, the holistic study of biochemical pathways requires computer modeling. Due to the complexity of cells, it is not feasible for one person or group to model the cell in its entirety.

Results: The Cell Collective is a platform that allows the world-wide scientific community to create these models collectively. Its interface enables users to build and use models without specifying any mathematical equations or computer code - addressing …

A Framework Genetic Map For Miscanthus Sinensis From Rnaseq-Based Markers Shows Recent Tetraploidy, Kankshita Swaminathan, Won Byoung Chae, Therese Mitros, Kranthi Varala, Liang Xie, Adam Barling, Katarzyna Glowacka, Megan Hall, Stanislaw Jezowski, Ray Ming, Matthew Hudson, John A. Juvik, Daniel S. Rokhsar, Stephen P. Moose

Department of Biochemistry: Faculty Publications

Background: Miscanthus (subtribe Saccharinae, tribe Andropogoneae, family Poaceae) is a genus of temperate perennial C4 grasses whose high biomass production makes it, along with its close relatives sugarcane and sorghum, attractive as a biofuel feedstock. The base chromosome number of Miscanthus (x = 19) is different from that of other Saccharinae and approximately twice that of the related Sorghum bicolor (x = 10), suggesting largescale duplications may have occurred in recent ancestors of Miscanthus. Owing to the complexity of the Miscanthus genome and the complications of self-incompatibility, a complete genetic map with a high density of markers has not …

Homologous Recombination In Nannochloropsis: A Powerful Tool In An Industrially Relevant Alga, Donald P. Weeks

Department of Biochemistry: Faculty Publications

The availability of facile methods for targeted gene knockout and gene replacement based on homologous recombination in bacteria and yeast systems has driven rapid progress in understanding many of the complex metabolic and regulatory networks in prokaryotic and eukaryotic cells. The lack of such tools in other organisms is a major impediment to progress both in fundamental research and in research that is directed toward practical economic and societal outcomes. For example, the current goal to replace fossil fuels with renewable energy sources produced by plants and algae is hampered in both the short term and the long term by …

Boron Stress Activates The General Amino Acid Control Mechanism And Inhibits Protein Synthesis, Irem Uluisik, Alaattin Kaya, Dmitri E. Fomenko, Huseyin C. Karakaya, Bradley A. Carlson, Vadim N. Gladyshev, Ahmet Koc

Department of Biochemistry: Faculty Publications

Boron is an essential micronutrient for plants, and it is beneficial for animals. However, at high concentrations boron is toxic to cells although the mechanism of this toxicity is not known. Atr1 has recently been identified as a boron efflux pump whose expression is upregulated in response to boron treatment. Here, we found that the expression of ATR1 is associated with expression of genes involved in amino acid biosynthesis. These mechanisms are strictly controlled by the transcription factor Gcn4 in response to boron treatment. Further analyses have shown that boron impaired protein synthesis by promoting phosphorylation of eIF2α in a …

Iron Insufficiency Compromises Motor Neurons And Their Mitochondrial Function In Irp2-Null Mice, Suh Young Jeong, Daniel R. Crooks, Hayden Wilson-Ollivierre, Manik C. Ghosh, Rachid Sougrat, Jaekwon Lee, Sharon Cooperman, James B. Mitchell, Carole Beaumont, Tracey A. Rouault

Department of Biochemistry: Faculty Publications

Genetic ablation of Iron Regulatory Protein 2 (Irp2, Ireb2), which post-transcriptionally regulates iron metabolism genes, causes a gait disorder in mice that progresses to hind-limb paralysis. Here we have demonstrated that misregulation of iron metabolism from loss of Irp2 causes lower motor neuronal degeneration with significant spinal cord axonopathy. Mitochondria in the lumbar spinal cord showed significantly decreased Complex I and II activities, and abnormal morphology. Lower motor neurons appeared to be the most adversely affected neurons, and we show that functional iron starvation due to misregulation of iron import and storage proteins, including transferrin receptor 1 …

Sphingolipids Containing Very-Long-Chain Fatty Acids Define A Secretory Pathway For Specific Polar Plasma Membrane Protein Targeting In Arabidopsis, Jennifer E. Markham, Diana Molino, Lionel Gissot, Yannick Bellec, Kian Hématy, Jessica Marion, Katia Belcram, Jean-Christophe Palauqui, Béatrice Satiat-Jeunemaître, Jean-Denis Faure

Department of Biochemistry: Faculty Publications

Sphingolipids are a class of structural membrane lipids involved in membrane trafficking and cell polarity. Functional analysis of the ceramide synthase family in Arabidopsis thaliana demonstrates the existence of two activities selective for the length of the acyl chains. Very-long-acyl-chain (C > 18 carbons) but not long-chain sphingolipids are essential for plant development. Reduction of very-long-chain fatty acid sphingolipid levels leads in particular to auxin-dependent inhibition of lateral root emergence that is associated with selective aggregation of the plasma membrane auxin carriers AUX1 and PIN1 in the cytosol. Defective targeting of polar auxin carriers is characterized by specific aggregation of Rab-A2a– …

Sphingolipids In The Root Play An Important Role In Regulating The Leaf Ionome In Arabidopsis Thaliana, Dai-Yin Chao, Kenneth Gable, Ming Chen, Ivan Baxter, Charles R. Dietrich, Edgar B. Cahoon, Mary Lou Guerinot, Brett Lahner, Shiyu Lu, Jennifer E. Markham, Joe Morrissey, Gongshe Han, Sita Gupta, Jeffrey M. Harmon, Jan G. Jaworski, Teresa M. Dunn, David E. Salt

Department of Biochemistry: Faculty Publications

Sphingolipid synthesis is initiated by condensation of Ser with palmitoyl-CoA producing 3-ketodihydrosphinganine (3-KDS), which is reduced by a 3-KDS reductase to dihydrosphinganine. Ser palmitoyltransferase is essential for plant viability. Arabidopsis thaliana contains two genes (At3g06060/TSC10A and At5g19200/TSC10B) encoding proteins with significant similarity to the yeast 3-KDS reductase, Tsc10p. Heterologous expression in yeast of either Arabidopsis gene restored 3-KDS reductase activity to the yeast tsc10D mutant, confirming both as bona fide 3-KDS reductase genes. Consistent with sphingolipids having essential functions in plants, double mutant progeny lacking both genes were not recovered from crosses of single tsc10A and tsc10B …

Mne1 Is A Novel Component Of The Mitochondrial Splicing Apparatus Responsible For Processing Of A Cox1 Group I Intron In Yeast, Talina Watts, Oleh Khalimonchuk, Rachel Z. Wolf, Edward M. Turk, Georg Mohr, Dennis R. Winge

Department of Biochemistry: Faculty Publications

Saccharomyces cerevisiae cells lacking Mne1 are deficient in

intron splicing in the gene encoding the Cox1 subunit of cytochrome

oxidase but contain wild-type levels of the bc1 complex.

Thus, Mne1 has no role in splicing of COB introns or expression

of the COB gene. Northern experiments suggest that splicing of

the COX1 aI5β intron is dependent on Mne1 in addition to the

previously known Mrs1, Mss116, Pet54, and Suv3 factors. Processing

of the aI5_ intron is similarly impaired in mne1∆ and

mrs1∆ cells and overexpression of Mrs1 partially restores the

respiratory function of mne1∆ cells. Mrs1 …

Differential Transcription Of Cytochrome P450s And Glutathione S Transferases In Ddt-Susceptible And -Resistant Drosophila Melanogaster Strains In Response To Ddt And Oxidative Stress, Lijie Sun, Brandi Schemerhorn, Amber Jannasch, Kent R. Walters Jr., Jiri Adamec, William M. Muir, Barry R. Pittendrigh

Department of Biochemistry: Faculty Publications

Metabolic DDT resistance in Drosophila melanogaster has previously been associated with constitutive over-transcription of cytochrome P450s. Increased P450 activity has also been associated with increased oxidative stress. In contrast, over-transcription of glutathione S transferases (GSTs) has been associated with resistance to oxidative stress. However, little is known in regards to the impact of xenobiotics on induction of P450s and GSTs and if there exist differences in inducibility between the pesticide susceptible and resistant strains. Thus, we investigated the transcriptional expression of GSTs and P450s in DDT resistant (Wisconsin) and susceptible (Canton-S) Drosophila strains in response to …

Thiol Peroxidases Mediate Specific Genome-Wide Regulation Of Gene Expression In Response To Hydrogen Peroxide, Dmitri E. Fomenko, Ahmet Koc, Natalia Agisheva, Michael Jacobsen, Alaattin Kaya, Mikalai Malinouski, Julian C. Rutherford, Kam-Leung Siu, Dong-Yan Jin, Dennis R. Winge, Vadim N. Gladyshev

Department of Biochemistry: Faculty Publications

Hydrogen peroxide is thought to regulate cellular processes by direct oxidation of numerous cellular proteins, whereas antioxidants, most notably thiol peroxidases, are thought to reduce peroxides and inhibit H₂O₂ response. However, thiol peroxidases have also been implicated in activation of transcription factors and signaling. It remains unclear if these enzymes stimulate or inhibit redox regulation and whether this regulation is widespread or limited to a few cellular components. Herein, we found that Saccharomyces cerevisiae cells lacking all eight thiol peroxidases were viable and withstood redox stresses. They transcriptionally responded to various redox treatments, but were unable to …

Hydrogen Peroxide Probes Directed To Different Cellular Compartments, Mikalai Malinouski, You Zhou, Vsevolod V. Belousov, Dolph L. Hatfield, Vadim N. Gladyshev

Department of Biochemistry: Faculty Publications

Background: Controlled generation and removal of hydrogen peroxide play important roles in cellular redox homeostasis and signaling. We used a hydrogen peroxide biosensor HyPer, targeted to different compartments, to examine these processes in mammalian cells.

Principal Findings: Reversible responses were observed to various redox perturbations and signaling events. HyPer expressed in HEK 293 cells was found to sense low micromolar levels of hydrogen peroxide. When targeted to various cellular compartments, HyPer occurred in the reduced state in the nucleus, cytosol, peroxisomes, mitochondrial intermembrane space and mitochondrial matrix, but low levels of the oxidized form of the biosensor were also observed …

Targeted Deletion Of The Mouse Mitoferrin1 Gene: From Anemia To Protoporphyria, Marie-Berengere Troadec, David Warner, Jared Wallace, Kirk Thomas, Gerald J. Spangrude, John Phillips, Oleh Khalimonchuk, Barry H. Paw, Diane Mcvey Ward, Jerry Kaplan

Department of Biochemistry: Faculty Publications

Mitoferrin1 is 1 of 2 homologous mitochondrial iron transporters and is required for mitochondrial iron delivery in developing erythroid cells. We show that total deletion of Mfrn1 in embryos leads to embryonic lethality. Selective deletion of Mfrn1 in adult hematopoietic tissues leads to severe anemia because of a deficit in erythroblast formation. Deletion of Mfrn1 in hepatocytes has no phenotype or biochemical effect under normal conditions. In the presence of increased porphyrin synthesis, however, deletion of Mfrn1 in hepatocytes results in a decreased ability to convert protoporphyrin IX into heme, leading to protoporphyria, cholestasis, and bridging cirrhosis. Our results show …

Genome-Wide Ribosome Profiling Reveals Complex Translational Regulation In Response To Oxidative Stress, Maxim V. Gerashchenko, Alexei V. Lobanov, Vadim N. Gladyshev

Department of Biochemistry: Faculty Publications

Information on unique and coordinated regulation of transcription and translation in response to stress is central to the understanding of cellular homeostasis. Here we used ribosome profiling coupled with next-generation sequencing to examine the interplay between transcription and translation under conditions of hydrogen peroxide treatment in Saccharomyces cerevisiae. Hydrogen peroxide treatment led to a massive and rapid increase in ribosome occupancy of short upstream ORFs, including those with non-AUG translational starts, and of the N-terminal regions of ORFs that preceded the transcriptional response. In addition, this treatment induced the synthesis of N-terminally extended proteins and elevated stop codon read-through …

Reduced Utilization Of Selenium By Naked Mole Rats Due To A Specific Defect In Gpx1 Expression, Marina V. Kasaikina, Alexei V. Lobanov, Mikalai I. Malinouski, Byung Cheon Lee, Javier Seravalli, Dmitri E. Fomenko, Anton A. Turanov, Lydia Finney, Stefan Vogt, Thomas J. Park, Richard A. Miller, Dolph L. Hatfield, Vadim N. Gladyshev

Department of Biochemistry: Faculty Publications

Naked mole rat (MR) Heterocephalus glaber is a rodent model of delayed aging because of its unusually long life span (>28 years). It is also not known to develop cancer. In the current work, tissue imaging by x-ray fluorescence microscopy and direct analyses of trace elements revealed low levels of selenium in the MR liver and kidney, whereas MR and mouse brains had similar selenium levels. This effect was not explained by uniform selenium deficiency because methionine sulfoxide reductase activities were similar in mice and MR. However, glutathione peroxidase activity was an order of magnitude lower inMRliver and kidney …

A 4-Selenocysteine, 2-Selenocysteine Insertion Sequence (Secis) Element Methionine Sulfoxide Reductase From Metridium Senile Reveals A Non-Catalytic Function Of Selenocysteines, Byung Cheon Lee, Alexey V. Lobanov, Stefano M. Marino, Alaattin Kaya, Javier Seravalli, Dolph L. Hatfield, Vadim N. Gladyshev

Department of Biochemistry: Faculty Publications

Selenocysteine (Sec) residues occur in thiol oxidoreductase families, and functionally characterized selenoenzymes typically have a single Sec residue used directly for redox catalysis. However, how new Sec residues evolve and whether non-catalytic Sec residues exist in proteins is not known. Here, we computationally identified several genes with multiple Sec insertion sequence (SECIS) elements, one of which was a methionine-Rsulfoxide reductase (MsrB) homolog from Metridium senile that has four in-frame UGA codons and two nearly identical SECIS elements. One of the UGA codons corresponded to the conserved catalytic Sec or Cys in MsrBs, whereas the three other UGA codons evolved recently …

Escherichia Coli Thioredoxin-Like Protein Ybbn Contains An Atypical Tetratricopeptide Repeat Motif And Is A Negative Regulator Of Groel, Jiusheng Lin, Mark A. Wilson

Department of Biochemistry: Faculty Publications

Many proteins contain a thioredoxin (Trx)-like domain fused with one or more partner domains that diversify protein function by the modular construction of new molecules. The Escherichia coli protein YbbN is a Trx-like protein that contains a C-terminal domain with low homology to tetratricopeptide repeat motifs. YbbN has been proposed to act as a chaperone or co-chaperone that aids in heat stress response andDNAsynthesis. We report the crystal structure of YbbN, which is an elongated molecule with a mobile Trx domain and four atypical tetratricopeptide repeat motifs. The Trx domain lacks a canonical CXXC active site architecture and is not …

Defining A Relationship Between Dietary Fatty Acids And The Cytochrome P450 System In A Mouse Model Of Fatty Liver Disease, Monika Gonzalez, Whitney Sealls, Elliot D. Jesch, M. Julia Brosnan, Istvan Ladunga, Xinxin Ding, Paul N. Black, Concetta C. Dirusso

Department of Biochemistry: Faculty Publications

Liver-specific ablation of cytochrome P450 reductase in mice (LCN) results in hepatic steatosis that can progress to steatohepatitis characterized by inflammation and fibrosis. The specific cause of the fatty liver phenotype is poorly understood but is hypothesized to result from elevated expression of genes encoding fatty acid synthetic genes. Since expression of these genes is known to be suppressed by polyunsaturated fatty acids, we performed physiological and genomics studies to evaluate the effects of dietary linoleic and linolenic fatty acids (PUFA) or arachidonic and decosahexaenoic acids (HUFA) on the hepatic phenotypes of control and LCN mice by comparison with a …

Functional Diversification Of Thylakoidal Processing Peptidases In Arabidopsis Thaliana, Shih-Chi Hsu, Joshua K. Endow, Nicholas J. Ruppel, Rebecca Roston, Amy J. Baldwin, Kentaro Inoue

Department of Biochemistry: Faculty Publications

Thylakoidal processing peptidase (TPP) is responsible for removing amino-terminal thylakoid-transfer signals from several proteins in the thylakoid lumen. Three TPP isoforms are encoded by the nuclear genome of Arabidopsis thaliana. Previous studies showed that one of them termed plastidic type I signal peptidase 1 (Plsp1) was necessary for processing three thylakoidal proteins and one protein in the chloroplast envelope in vivo. The lack of Plsp1 resulted in seedling lethality, apparently due to disruption of proper thylakoid development. The physiological roles of the other two TPP homologs remain unknown. Here we show that the three A. thaliana TPP isoforms …

Enzymatic Defects Underlying Hereditary Glutamate Cysteine Ligase Deficiency Are Mitigated By Association Of The Catalytic And Regulatory Subunits, Melanie Neely Willis, Yilin Liu, Ekaterina I. Biterova, Melanie A. Simpson, Heejeong Kim, Jaekwon Lee, Joseph J. Barycki

Department of Biochemistry: Faculty Publications

Glutamate cysteine ligase (GCL) deficiency is a rare autosomal recessive trait that compromises

production of glutathione, a critical redox buffer and enzymatic cofactor. Patients have markedly

reduced levels of erythrocyte glutathione, leading to hemolytic anemia and in some cases,

impaired neurological function. Human glutamate cysteine ligase is a heterodimer comprised of a

catalytic (GCLC) and a regulatory subunit (GCLM), which catalyzes the initial rate limiting step

in glutathione production. Four clinical missense mutations have been identified within GCLC:

Arg127Cys, Pro158Leu, His370Leu, and Pro414Leu. Here, we have evaluated the impacts of

these mutations on enzymatic function in vivo and in vitro …