Medical Molecular Biology Commons^™

Interplay Between An Atp-Binding Cassette F Protein And The Ribosome From Mycobacterium Tuberculosis, Zhicheng Cui, Xiaojun Li, Joonyoung Shin, Howard Gamper, Ya-Ming Hou, James C Sacchettini, Junjie Zhang

Department of Biochemistry and Molecular Biology Faculty Papers

EttA, energy-dependent translational throttle A, is a ribosomal factor that gates ribosome entry into the translation elongation cycle. A detailed understanding of its mechanism of action is limited due to the lack of high-resolution structures along its ATPase cycle. Here we present the cryo-electron microscopy (cryo-EM) structures of EttA from Mycobacterium tuberculosis (Mtb), referred to as MtbEttA, in complex with the Mtb 70S ribosome initiation complex (70SIC) at the pre-hydrolysis (ADPNP) and transition (ADP-VO4) states, and the crystal structure of MtbEttA alone in the post-hydrolysis (ADP) state. We observe that MtbEttA binds the E-site of the Mtb 70SIC, remodeling the …

Distinct Mechanisms Control Genome Recognition By P53 At Its Target Genes Linked To Different Cell Fates., Marina Farkas, Hideharu Hashimoto, Yingtao Bi, Ramana V Davuluri, Lois Resnick-Silverman, James J. Manfredi, Erik W. Debler, Steven B. Mcmahon

Department of Biochemistry and Molecular Biology Faculty Papers

The tumor suppressor p53 integrates stress response pathways by selectively engaging one of several potential transcriptomes, thereby triggering cell fate decisions (e.g., cell cycle arrest, apoptosis). Foundational to this process is the binding of tetrameric p53 to 20-bp response elements (REs) in the genome (RRRCWWGYYYN_0-13RRRCWWGYYY). In general, REs at cell cycle arrest targets (e.g. p21) are of higher affinity than those at apoptosis targets (e.g., BAX). However, the RE sequence code underlying selectivity remains undeciphered. Here, we identify molecular mechanisms mediating p53 binding to high- and low-affinity REs by showing that key determinants of the code are embedded …

Economic Evaluation Of Lupus Nephritis In The Systemic Lupus International Collaborating Clinics Inception Cohort Using A Multistate Model Approach., M. R.W. Barber, J. G. Hanly, L. Su, M. B. Urowitz, Y. St Pierre, J. Romero-Diaz, C. Gordon, C. Aranow, M. Mackay, A. E. Clarke, +30 Additional Authors

Journal Articles

OBJECTIVE: Little is known about the long-term costs of lupus nephritis (LN). The costs were compared between patients with and without LN using multistate modeling.

METHODS: Patients from 32 centers in 11 countries were enrolled in the Systemic Lupus International Collaborating Clinics inception cohort within 15 months of diagnosis and provided annual data on renal function, hospitalizations, medications, dialysis, and selected procedures. LN was diagnosed by renal biopsy or the American College of Rheumatology classification criteria. Renal function was assessed annually using the estimated glomerular filtration rate (GFR) or estimated proteinuria. A multistate model was used to predict 10-year cumulative …

Conservation Of Structure And Mechanism By Trm5 Enzymes., Thomas Christian, Howard Gamper, Ya-Ming Hou

Department of Biochemistry and Molecular Biology Faculty Papers

Enzymes of the Trm5 family catalyze methyl transfer from S-adenosyl methionine (AdoMet) to the N¹ of G37 to synthesize m¹ G37-tRNA as a critical determinant to prevent ribosome frameshift errors. Trm5 is specific to eukaryotes and archaea, and it is unrelated in evolution from the bacterial counterpart TrmD, which is a leading anti-bacterial target. The successful targeting of TrmD requires detailed information on Trm5 to avoid cross-species inhibition. However, most information on Trm5 is derived from studies of the archaeal enzyme Methanococcus jannaschii (MjTrm5), whereas little information is available for eukaryotic enzymes. Here we use human Trm5 (Homo sapiens; HsTrm5) …

Impaired Expression Of Protein Phosphatase 2a Subunits Enhances Metastatic Potential Of Human Prostate Cancer Cells Through Activation Of Akt Pathway., P Pandey, Parthasarathy Seshacharyulu, Srustidhar Das, Satyanarayana Rachagani, Moorthy P. Ponnusamy, Y Yan, Sonny L. Johansson, K Datta, Ming-Fong Lin, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

BACKGROUND: Protein phosphatase 2A (PP2A) is a dephosphorylating enzyme, loss of which can contribute to prostate cancer (PCa) pathogenesis. The aim of this study was to analyse the transcriptional and translational expression patterns of individual subunits of the PP2A holoenzyme during PCa progression.

METHODS: Immunohistochemistry (IHC), western blot, and real-time PCR was performed on androgen-dependent (AD) and androgen-independent (AI) PCa cells, and benign and malignant prostate tissues for all the three PP2A (scaffold, regulatory, and catalytic) subunits. Mechanistic and functional studies were performed using various biochemical and cellular techniques.

RESULTS: Through immunohistochemical analysis we observed significantly reduced levels of PP2A-A …

Protein Synthesis Factors (Rf1, Rf2, Rf3, Rrf, And Tmrna) And Peptidyl-Trna Hydrolase Rescue Stalled Ribosomes At Sense Codons., Serafín Vivanco-Domínguez, José Bueno-Martínez, Gloria León-Avila, Nobuhiro Iwakura, Akira Kaji, Hideko Kaji, Gabriel Guarneros

Department of Biochemistry and Molecular Biology Faculty Papers

During translation, ribosomes stall on mRNA when the aminoacyl-tRNA to be read is not readily available. The stalled ribosomes are deleterious to the cell and should be rescued to maintain its viability. To investigate the contribution of some of the cellular translation factors on ribosome rescuing, we provoked stalling at AGA codons in mutants that affected the factors and then analyzed the accumulation of oligopeptidyl (peptides of up to 6 amino acid residues, oligopep-)-tRNA or polypeptidyl (peptides of more than 300 amino acids in length, polypep-)-tRNA associated with ribosomes. Stalling was achieved by starvation for aminoacyl-tRNA(Arg4) upon induced expression of …

Structure Of The Atp Synthase Catalytic Complex (F(1)) From Escherichia Coli In An Autoinhibited Conformation., Gino Cingolani, Thomas M Duncan

Department of Biochemistry and Molecular Biology Faculty Papers

ATP synthase is a membrane-bound rotary motor enzyme that is critical for cellular energy metabolism in all kingdoms of life. Despite conservation of its basic structure and function, autoinhibition by one of its rotary stalk subunits occurs in bacteria and chloroplasts but not in mitochondria. The crystal structure of the ATP synthase catalytic complex (F(1)) from Escherichia coli described here reveals the structural basis for this inhibition. The C-terminal domain of subunit ɛ adopts a heretofore unknown, highly extended conformation that inserts deeply into the central cavity of the enzyme and engages both rotor and stator subunits in extensive contacts …

Ribosome Recycling Step In Yeast Cytoplasmic Protein Synthesis Is Catalyzed By Eef3 And Atp., Shinya Kurata, Klaus H Nielsen, Sarah F Mitchell, Jon R Lorsch, Akira Kaji, Hideko Kaji

Department of Biochemistry and Molecular Biology Faculty Papers

After each round of protein biosynthesis, the posttermination complex (PoTC) consisting of a ribosome, mRNA, and tRNA must be disassembled into its components for a new round of translation. Here, we show that a Saccharomyces cerevisiae model PoTC was disassembled by ATP and eukaryotic elongation factor 3 (eEF3). GTP or ITP functioned with less efficiency and adenosine 5gamma'-(beta,gamma-imido)triphosphate did not function at all. The k(cat) of eEF3 was 1.12 min(-1), which is comparable to that of the in vitro initiation step. The disassembly reaction was inhibited by aminoglycosides and cycloheximide. The subunits formed from the yeast model PoTC remained separated …

P66shc--A Longevity Redox Protein In Human Prostate Cancer Progression And Metastasis : P66shc In Cancer Progression And Metastasis., Mythilypriya Rajendran, Paul Thomes, Li Zhang, Suresh Veeramani, Ming-Fong Lin

Journal Articles: Biochemistry & Molecular Biology

p66Shc, a 66 kDa proto-oncogene Src homologous-collagen homologue (Shc) adaptor protein, is classically known in mediating receptor tyrosine kinase signaling and recently identified as a sensor to oxidative stress-induced apoptosis and as a longevity protein in mammals. The expression of p66Shc is decreased in mice and increased in human fibroblasts upon aging and in aging-related diseases, including prostate cancer. p66Shc protein level correlates with the proliferation of several carcinoma cells and can be regulated by steroid hormones. Recent advances point that p66Shc protein plays a role in mediating cross-talk between steroid hormones and redox signals by serving as a common …

The Human Rna Polymerase Ii-Associated Factor 1 (Hpaf1): A New Regulator Of Cell-Cycle Progression., Nicolas Moniaux, Christophe Nemos, Shonali Deb, Bing Zhu, Irena Dornreiter, Michael A. Hollingsworth, Surinder K. Batra

Journal Articles: Biochemistry & Molecular Biology

BACKGROUND: The human PAF (hPAF) complex is part of the RNA polymerase II transcription apparatus and regulates multiple steps in gene expression. Further, the yeast homolog of hPaf1 has a role in regulating the expression of a subset of genes involved in the cell-cycle. We therefore investigated the role of hPaf1 during progression of the cell-cycle.

METHODOLOGY/FINDINGS: Herein, we report that the expression of hPaf1, a subunit of the hPAF complex, increases with cell-cycle progression and is regulated in a cell-cycle dependant manner. hPaf1 specifically regulates a subclass of genes directly implicated in cell-cycle progression during G1/S, S/G2, and G2/M. …

Revisiting Histidine-Dependent Acid Phosphatases: A Distinct Group Of Tyrosine Phosphatases., Suresh Veeramani, Ming-Shyue Lee, Ming-Fong Lin

Journal Articles: Biochemistry & Molecular Biology

Although classical protein tyrosine phosphatase (PTP) superfamily members are cysteine-dependent, emerging evidence shows that many acid phosphatases (AcPs) function as histidine-dependent PTPs in vivo. These AcPs dephosphorylate phospho-tyrosine substrates intracellularly and could have roles in development and disease. In contrast to cysteine-dependent PTPs, they utilize histidine, rather than cysteine, for substrate dephosphorylation. Structural analyses reveal that active site histidine, but not cysteine, faces towards the substrate and functions as the phosphate acceptor. Nonetheless, during dephosphorylation, both histidine-dependent and cysteine-dependent PTPs use their active site arginine and aspartate for substrate binding and proton donation, respectively. Thus, we propose that they should …

Caveolin-1, Tgf-Β Receptor Internalization, And The Pathogenesis Of Systemic Sclerosis, Francesco Del Galdo, Michael P. Lisanti, Sergio A. Jimenez

Jefferson Institute of Molecular Medicine Papers and Presentations

PURPOSE OF REVIEW: To review the scientific literature supporting the participation of caveolin-1 in the pathogenesis of tissue fibrosis and the notion that modulation of the caveolin-1 pathway may represent a novel treatment for systemic sclerosis and other fibrotic diseases.

RECENT FINDINGS: Caveolin-1 plays an important role in the regulation of transforming growth factor-beta (TGF-beta) signaling owing to its participation in TGF-beta receptor internalization. TGF-beta receptor internalized through caveolin-1 lipid rafts undergoes rapid degradation, effectively decreasing TGF-beta signaling. Studies have shown that caveolin-1 knockdown in vitro markedly increased collagen gene expression in normal human lung fibroblasts. Caveolin-1 was reduced in …

Mitochondrial Redox Signaling By P66shc Is Involved In Regulating Androgenic Growth Stimulation Of Human Prostate Cancer Cells., Suresh Veeramani, Ta-Chun Yuan, Fen-Fen Lin, Ming-Fong Lin

Journal Articles: Biochemistry & Molecular Biology

p66Shc is shown to negatively regulate the life span in mice through reactive oxygen species (ROS) production. Recent reports, however, revealed that p66Shc protein level is significantly elevated in several human cancer tissues and growth-stimulated carcinoma cells, suggesting a mitogenic and carcinogenic role for p66Shc. In this communication, we demonstrate for the first time that p66Shc mediates androgenic growth signals in androgen-sensitive human prostate cancer cells through mitochondrial ROS production. Growth stimulation of prostate cancer cells with 5alpha-dihydrotestosterone (DHT) is accompanied by increased p66Shc level and ROS production, which is abolished by antioxidant treatments. However, antioxidant treatments do not affect …

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) …

An Intramolecular Association Between Two Domains Of The Protein Kinase Fused Is Necessary For Hedgehog Signaling, Manuel Ascano Jr., David J. Robbins

Dartmouth Scholarship

The protein kinase Fused (Fu) is an integral member of the Hedgehog (Hh) signaling pathway. Although genetic studies demonstrate that Fu is required for the regulation of the Hh pathway, the mechanistic role that it plays remains largely unknown. Given our difficulty in developing an in vitro kinase assay for Fu, we reasoned that the catalytic activity of Fu might be highly regulated. Several mechanisms are known to regulate protein kinases, including self-association in either an intra- or an intermolecular fashion. Here, we provide evidence that Hh regulates Fu through intramolecular association between its kinase domain (ΔFu) and its carboxyl-terminal …