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Medellin B, Yang W, Konduri S, Dong J, Irani S, Wu H, Matthews WL, Zhang ZY, Siegel D, Zhang Y. Targeted Covalent Inhibition of Small CTD Phosphatase 1 to Promote the Degradation of the REST Transcription Factor in Human Cells. J Med Chem 2022; 65:507-519. [PMID: 34931516 PMCID: PMC8826594 DOI: 10.1021/acs.jmedchem.1c01655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The repressor element-1 silencing transcription factor (REST) represses neuronal gene expression, whose dysregulation is implicated in brain tumors and neurological diseases. A high level of REST protein drives the tumor growth in some glioblastoma cells. While transcription factors like REST are challenging targets for small-molecule inhibitors, the inactivation of a regulatory protein, small CTD phosphatase 1 (SCP1), promotes REST degradation and reduces transcriptional activity. This study rationally designed a series of α,β-unsaturated sulfones to serve as potent and selective covalent inhibitors against SCP1. The compounds inactivate SCP1 via covalent modification of Cys181 located at the active site entrance. Cellular studies showed that the inhibitors inactivate SCP1 in a time- and dose-dependent manner with an EC50 ∼1.5 μM, reducing REST protein levels and activating specific REST-suppressed genes. These compounds represent a promising line of small-molecule inhibitors as a novel lead for glioblastoma whose growth is driven by REST transcription activity.
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Affiliation(s)
| | | | - Srihari Konduri
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093, United States
| | - Jiajun Dong
- Department of Medicinal Chemistry and Molecular Pharmacology and Department of Chemistry, Institute for Drug Discovery, Purdue University, West Lafayette, Indiana 47907, United States
| | - Seema Irani
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Haoyi Wu
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Wendy L. Matthews
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Zhong-Yin Zhang
- Department of Medicinal Chemistry and Molecular Pharmacology and Department of Chemistry, Institute for Drug Discovery, Purdue University, West Lafayette, Indiana 47907, United States
| | - Dionico Siegel
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093, United States
| | - Yan Zhang
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, United States
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2
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Deubiquitinase USP29 promotes gastric cancer cell migration by cooperating with phosphatase SCP1 to stabilize Snail protein. Oncogene 2020; 39:6802-6815. [PMID: 32973332 DOI: 10.1038/s41388-020-01471-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Revised: 08/26/2020] [Accepted: 09/15/2020] [Indexed: 01/07/2023]
Abstract
Snail is a master inducer of epithelial-mesenchymal transition (EMT) and metastasis, however, Snail protein is labile and is quickly degraded through the predominate ubiquitination-mediated proteasome pathway. Deubiquitinases (DUBs) can counteract the Snail degradation process to maintain high level of Snail protein in cancer cells. In this study, we screened a cDNA library containing 79 DUBs, and discovered that a panel of DUBs consisting of USP13, USP28, USP29, USP37, OTUD6A, and DUB3 can markedly stabilize Snail protein, with USP29 displaying the strongest activity to prevent Snail degradation. Mechanistically, USP29 enhances the interaction of Snail and SCP1, resulting in simultaneous dephosphorylation and deubiquitination of Snail and thereafter cooperative prevention of Snail degradation. Biologically, ectopic expression of USP29 promotes gastric cancer cell migration, and depletion of Snail abolishes USP29-mediated cell migration; and USP29 can be induced by major EMT and metastatic inducing factors such as TGFβ, TNFα, and hypoxia. More importantly, high expression levels of Snail, USP29, and SCP1 are associated with poor survival and prognosis. Collectively, these data indicate that Snail is a crucial substrate for USP29 to promote cell migration and USP29/SCP1 complex may be new therapeutic targets to treat metastatic cancer.
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3
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Tumor suppressor properties of the small C-terminal domain phosphatases in non-small cell lung cancer. Biosci Rep 2020; 39:221348. [PMID: 31774910 PMCID: PMC6911153 DOI: 10.1042/bsr20193094] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 11/17/2019] [Accepted: 11/19/2019] [Indexed: 02/07/2023] Open
Abstract
Non-Small Cell Lung Cancer (NSCLC) is responsible for the majority of deaths caused by cancer. Small C-terminal domain (CTD) phosphatases (SCP), CTDSP1, CTDSP2 and CTDSPL (CTDSPs) belong to SCP/CTDSP subfamily and are involved in many vital cellular processes and tumorigenesis. High similarity of their structures suggests similar functions. However their role in NSCLC remains insufficiently understood. For the first time we revealed the suppressor function of CTDSPs leading to a significant growth slowdown and senescence of A549 lung adenocarcinoma (ADC) cells in vitro. Their tumor-suppressive activity can be realized through increasing the proportion of the active form of Rb protein dephosphorylated at Ser807/811, Ser780, and Ser795 (P<0.05) thereby negatively regulating cancer cell proliferation. Moreover, we observed that a frequent (84%, 39/46) and highly concordant (Spearman's rank correlation coefficient (rs) = 0.53-0.62, P≤0.01) down-regulation of CTDSPs and RB1 is characteristic of primary NSCLC samples (n=46). A clear difference in their mRNA levels was found between lung ADCs with and without lymph node metastases, but not in squamous cell carcinomas (SCCs) (P≤0.05). Based on The Cancer Genome Atlas (TCGA) data and the results obtained using the CrossHub tool, we suggest that the well-known oncogenic cluster miR-96/182/183 could be a common expression regulator of CTDSPs. Indeed, according to our qPCR, the expression of CTDSPs negatively correlates with these miRs, but positively correlates with their intronic miR-26a/b. Our results reflect functional association of CTDSP1, CTDSP2, and CTDSPL, expand knowledge about their suppressor properties through Rb dephosphorylation and provide new insights into the regulation of NSCLC growth.
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Rallabandi HR, Lee D, Sung J, Kim YJ. Peripheral Inhibition of Small C‐Terminal Domain Phosphatase 1 With Napthoquinone Analogs. B KOREAN CHEM SOC 2020. [DOI: 10.1002/bkcs.12051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Harikrishna Reddy Rallabandi
- Department of Medicinal Biosciences and Nanotechnology Research CenterKonkuk University Chungju 27478 Republic of Korea
| | - Dongsun Lee
- Department of Medicinal Biosciences and Nanotechnology Research CenterKonkuk University Chungju 27478 Republic of Korea
| | - Jinmo Sung
- Department of Medicinal Biosciences and Nanotechnology Research CenterKonkuk University Chungju 27478 Republic of Korea
| | - Young Jun Kim
- Department of Medicinal Biosciences and Nanotechnology Research CenterKonkuk University Chungju 27478 Republic of Korea
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5
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Lyons DE, McMahon S, Ott M. A combinatorial view of old and new RNA polymerase II modifications. Transcription 2020; 11:66-82. [PMID: 32401151 DOI: 10.1080/21541264.2020.1762468] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The production of mRNA is a dynamic process that is highly regulated by reversible post-translational modifications of the C-terminal domain (CTD) of RNA polymerase II. The CTD is a highly repetitive domain consisting mostly of the consensus heptad sequence Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7. Phosphorylation of serine residues within this repeat sequence is well studied, but modifications of all residues have been described. Here, we focus on integrating newly identified and lesser-studied CTD post-translational modifications into the existing framework. We also review the growing body of work demonstrating crosstalk between different CTD modifications and the functional consequences of such crosstalk on the dynamics of transcriptional regulation.
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Affiliation(s)
- Danielle E Lyons
- Gladstone Institute of Virology and Immunology, San Francisco, CA, USA
| | - Sarah McMahon
- Gladstone Institute of Virology and Immunology, San Francisco, CA, USA.,Department of Medicine, University of California, San Francisco , San Francisco, CA, USA
| | - Melanie Ott
- Gladstone Institute of Virology and Immunology, San Francisco, CA, USA.,Department of Medicine, University of California, San Francisco , San Francisco, CA, USA
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6
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Rallabandi HR, Ganesan P, Kim YJ. Targeting the C-Terminal Domain Small Phosphatase 1. Life (Basel) 2020; 10:life10050057. [PMID: 32397221 PMCID: PMC7281111 DOI: 10.3390/life10050057] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 05/05/2020] [Accepted: 05/07/2020] [Indexed: 12/15/2022] Open
Abstract
The human C-terminal domain small phosphatase 1 (CTDSP1/SCP1) is a protein phosphatase with a conserved catalytic site of DXDXT/V. CTDSP1’s major activity has been identified as dephosphorylation of the 5th Ser residue of the tandem heptad repeat of the RNA polymerase II C-terminal domain (RNAP II CTD). It is also implicated in various pivotal biological activities, such as acting as a driving factor in repressor element 1 (RE-1)-silencing transcription factor (REST) complex, which silences the neuronal genes in non-neuronal cells, G1/S phase transition, and osteoblast differentiation. Recent findings have denoted that negative regulation of CTDSP1 results in suppression of cancer invasion in neuroglioma cells. Several researchers have focused on the development of regulating materials of CTDSP1, due to the significant roles it has in various biological activities. In this review, we focused on this emerging target and explored the biological significance, challenges, and opportunities in targeting CTDSP1 from a drug designing perspective.
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7
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Nozaka A, Nishiwaki A, Nagashima Y, Endo S, Kuroki M, Nakajima M, Narukawa M, Kamisuki S, Arazoe T, Taguchi H, Sugawara F, Kamakura T. Chloramphenicol inhibits eukaryotic Ser/Thr phosphatase and infection-specific cell differentiation in the rice blast fungus. Sci Rep 2019; 9:9283. [PMID: 31243315 PMCID: PMC6594944 DOI: 10.1038/s41598-019-41039-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 02/25/2019] [Indexed: 01/23/2023] Open
Abstract
Chloramphenicol (Cm) is a broad-spectrum classic antibiotic active against prokaryotic organisms. However, Cm has severe side effects in eukaryotes of which the cause remains unknown. The plant pathogenic fungus Magnaporthe oryzae, which causes rice blast, forms an appressorium to infect the host cell via single-cell differentiation. Chloramphenicol specifically inhibits appressorium formation, which indicates that Cm has a novel molecular target (or targets) in the rice blast fungus. Application of the T7 phage display method inferred that MoDullard, a Ser/Thr-protein phosphatase, may be a target of Cm. In animals Dullard functions in cell differentiation and protein synthesis, but in fungi its role is poorly understood. In vivo and in vitro analyses showed that MoDullard is required for appressorium formation, and that Cm can bind to and inhibit MoDullard function. Given that human phosphatase CTDSP1 complemented the MoDullard function during appressorium formation by M. oryzae, CTDSP1 may be a novel molecular target of Cm in eukaryotes.
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Affiliation(s)
- Akihito Nozaka
- Tokyo University of Science, Department of Applied Biological Science, Faculty of Science and Technology, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Ayaka Nishiwaki
- Tokyo University of Science, Department of Applied Biological Science, Faculty of Science and Technology, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Yuka Nagashima
- Tokyo University of Science, Department of Applied Biological Science, Faculty of Science and Technology, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Shogo Endo
- Tokyo University of Science, Department of Applied Biological Science, Faculty of Science and Technology, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Misa Kuroki
- Tokyo University of Science, Department of Applied Biological Science, Faculty of Science and Technology, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Masahiro Nakajima
- Tokyo University of Science, Department of Applied Biological Science, Faculty of Science and Technology, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Megumi Narukawa
- Osaka University, Research Institute for Microbial Diseases, Department of Molecular Microbiology, 3-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Shinji Kamisuki
- Azabu University, Department of Veterinary Science, Laboratory of Basic Education, 1-17-71 Fuchinobe, Chuo-ku, Sagamihara-shi, Kanagawa, 252-5201, Japan
| | - Takayuki Arazoe
- Tokyo University of Science, Department of Applied Biological Science, Faculty of Science and Technology, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Hayao Taguchi
- Tokyo University of Science, Department of Applied Biological Science, Faculty of Science and Technology, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Fumio Sugawara
- Tokyo University of Science, Department of Applied Biological Science, Faculty of Science and Technology, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Takashi Kamakura
- Tokyo University of Science, Department of Applied Biological Science, Faculty of Science and Technology, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan.
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8
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Burkholder NT, Mayfield JE, Yu X, Irani S, Arce DK, Jiang F, Matthews WL, Xue Y, Zhang YJ. Phosphatase activity of small C-terminal domain phosphatase 1 (SCP1) controls the stability of the key neuronal regulator RE1-silencing transcription factor (REST). J Biol Chem 2018; 293:16851-16861. [PMID: 30217818 DOI: 10.1074/jbc.ra118.004722] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 08/20/2018] [Indexed: 02/03/2023] Open
Abstract
The RE1-silencing transcription factor (REST) is the major scaffold protein for assembly of neuronal gene silencing complexes that suppress gene transcription through regulating the surrounding chromatin structure. REST represses neuronal gene expression in stem cells and non-neuronal cells, but it is minimally expressed in neuronal cells to ensure proper neuronal development. Dysregulation of REST function has been implicated in several cancers and neurological diseases. Modulating REST gene silencing is challenging because cellular and developmental differences can affect its activity. We therefore considered the possibility of modulating REST activity through its regulatory proteins. The human small C-terminal domain phosphatase 1 (SCP1) regulates the phosphorylation state of REST at sites that function as REST degradation checkpoints. Using kinetic analysis and direct visualization with X-ray crystallography, we show that SCP1 dephosphorylates two degron phosphosites of REST with a clear preference for phosphoserine 861 (pSer-861). Furthermore, we show that SCP1 stabilizes REST protein levels, which sustains REST's gene silencing function in HEK293 cells. In summary, our findings strongly suggest that REST is a bona fide substrate for SCP1 in vivo and that SCP1 phosphatase activity protects REST against degradation. These observations indicate that targeting REST via its regulatory protein SCP1 can modulate its activity and alter signaling in this essential developmental pathway.
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Affiliation(s)
| | | | - Xiaohua Yu
- the Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China, and
| | | | | | - Faqin Jiang
- the School of Pharmacy, Shanghai Jiao Tong University, Shanghai 200240, China
| | | | - Yuanchao Xue
- the Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China, and
| | - Yan Jessie Zhang
- From the Departments of Molecular Biosciences and .,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712
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9
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Yu ZH, Zhang ZY. Regulatory Mechanisms and Novel Therapeutic Targeting Strategies for Protein Tyrosine Phosphatases. Chem Rev 2018; 118:1069-1091. [PMID: 28541680 PMCID: PMC5812791 DOI: 10.1021/acs.chemrev.7b00105] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
An appropriate level of protein phosphorylation on tyrosine is essential for cells to react to extracellular stimuli and maintain cellular homeostasis. Faulty operation of signal pathways mediated by protein tyrosine phosphorylation causes numerous human diseases, which presents enormous opportunities for therapeutic intervention. While the importance of protein tyrosine kinases in orchestrating the tyrosine phosphorylation networks and in target-based drug discovery has long been recognized, the significance of protein tyrosine phosphatases (PTPs) in cellular signaling and disease biology has historically been underappreciated, due to a large extent to an erroneous assumption that they are largely constitutive and housekeeping enzymes. Here, we provide a comprehensive examination of a number of regulatory mechanisms, including redox modulation, allosteric regulation, and protein oligomerization, that control PTP activity. These regulatory mechanisms are integral to the myriad PTP-mediated biochemical events and reinforce the concept that PTPs are indispensable and specific modulators of cellular signaling. We also discuss how disruption of these PTP regulatory mechanisms can cause human diseases and how these diverse regulatory mechanisms can be exploited for novel therapeutic development.
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Affiliation(s)
- Zhi-Hong Yu
- Department of Medicinal Chemistry and Molecular Pharmacology, Department of Chemistry, Center for Cancer Research, and Institute for Drug Discovery, Purdue University, 720 Clinic Drive, West Lafayette, IN 47907
| | - Zhong-Yin Zhang
- Department of Medicinal Chemistry and Molecular Pharmacology, Department of Chemistry, Center for Cancer Research, and Institute for Drug Discovery, Purdue University, 720 Clinic Drive, West Lafayette, IN 47907
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10
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Malhotra K, Modak A, Nangia S, Daman TH, Gunsel U, Robinson VL, Mokranjac D, May ER, Alder NN. Cardiolipin mediates membrane and channel interactions of the mitochondrial TIM23 protein import complex receptor Tim50. SCIENCE ADVANCES 2017; 3:e1700532. [PMID: 28879236 PMCID: PMC5580885 DOI: 10.1126/sciadv.1700532] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 08/04/2017] [Indexed: 05/07/2023]
Abstract
The phospholipid cardiolipin mediates the functional interactions of proteins that reside within energy-conserving biological membranes. However, the molecular basis by which this lipid performs this essential cellular role is not well understood. We address this role of cardiolipin using the multisubunit mitochondrial TIM23 protein transport complex as a model system. The early stages of protein import by this complex require specific interactions between the polypeptide substrate receptor, Tim50, and the membrane-bound channel-forming subunit, Tim23. Using analyses performed in vivo, in isolated mitochondria, and in reductionist nanoscale model membrane systems, we show that the soluble receptor domain of Tim50 interacts with membranes and with specific sites on the Tim23 channel in a manner that is directly modulated by cardiolipin. To obtain structural insights into the nature of these interactions, we obtained the first small-angle x-ray scattering-based structure of the soluble Tim50 receptor in its entirety. Using these structural insights, molecular dynamics simulations combined with a range of biophysical measurements confirmed the role of cardiolipin in driving the association of the Tim50 receptor with lipid bilayers with concomitant structural changes, highlighting the role of key structural elements in mediating this interaction. Together, these results show that cardiolipin is required to mediate specific receptor-channel associations in the TIM23 complex. Our results support a new working model for the dynamic structural changes that occur within the complex during transport. More broadly, this work strongly advances our understanding of how cardiolipin mediates interactions among membrane-associated proteins.
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Affiliation(s)
- Ketan Malhotra
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06269–3125, USA
| | - Arnab Modak
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06269–3125, USA
| | - Shivangi Nangia
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06269–3125, USA
| | - Tyler H. Daman
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06269–3125, USA
| | - Umut Gunsel
- Department of Physiological Chemistry, Biomedical Center Munich, Ludwig-Maximilian University of Munich, 82152 Planegg-Martinsried, Germany
| | - Victoria L. Robinson
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06269–3125, USA
| | - Dejana Mokranjac
- Department of Physiological Chemistry, Biomedical Center Munich, Ludwig-Maximilian University of Munich, 82152 Planegg-Martinsried, Germany
| | - Eric R. May
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06269–3125, USA
| | - Nathan N. Alder
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06269–3125, USA
- Corresponding author.
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11
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Irani S, Yogesha SD, Mayfield J, Zhang M, Zhang Y, Matthews WL, Nie G, Prescott NA, Zhang YJ. Structure of Saccharomyces cerevisiae Rtr1 reveals an active site for an atypical phosphatase. Sci Signal 2016; 9:ra24. [PMID: 26933063 DOI: 10.1126/scisignal.aad4805] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Changes in the phosphorylation status of the carboxyl-terminal domain (CTD) of RNA polymerase II (RNAPII) correlate with the process of eukaryotic transcription. The yeast protein regulator of transcription 1 (Rtr1) and the human homolog RNAPII-associated protein 2 (RPAP2) may function as CTD phosphatases; however, crystal structures of Kluyveromyces lactis Rtr1 lack a consensus active site. We identified a phosphoryl transfer domain in Saccharomyces cerevisiae Rtr1 by obtaining and characterizing a 2.6 Å resolution crystal structure. We identified a putative substrate-binding pocket in a deep groove between the zinc finger domain and a pair of helices that contained a trapped sulfate ion. Because sulfate mimics the chemistry of a phosphate group, this structural data suggested that this groove represents the phosphoryl transfer active site. Mutagenesis of the residues lining this groove disrupted catalytic activity of the enzyme assayed in vitro with a fluorescent chemical substrate, and expression of the mutated Rtr1 failed to rescue growth of yeast lacking Rtr1. Characterization of the phosphatase activity of RPAP2 and a mutant of the conserved putative catalytic site in the same chemical assay indicated a conserved reaction mechanism. Our data indicated that the structure of the phosphoryl transfer domain and reaction mechanism for the phosphoryl transfer activity of Rtr1 is distinct from those of other phosphatase families.
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Affiliation(s)
- Seema Irani
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - S D Yogesha
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Joshua Mayfield
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Mengmeng Zhang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Yong Zhang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Wendy L Matthews
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Grace Nie
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Nicholas A Prescott
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Yan Jessie Zhang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
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12
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Mayfield JE, Burkholder NT, Zhang YJ. Dephosphorylating eukaryotic RNA polymerase II. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:372-87. [PMID: 26779935 DOI: 10.1016/j.bbapap.2016.01.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 01/11/2016] [Accepted: 01/14/2016] [Indexed: 12/20/2022]
Abstract
The phosphorylation state of the C-terminal domain of RNA polymerase II is required for the temporal and spatial recruitment of various factors that mediate transcription and RNA processing throughout the transcriptional cycle. Therefore, changes in CTD phosphorylation by site-specific kinases/phosphatases are critical for the accurate transmission of information during transcription. Unlike kinases, CTD phosphatases have been traditionally neglected as they are thought to act as passive negative regulators that remove all phosphate marks at the conclusion of transcription. This over-simplified view has been disputed in recent years and new data assert the active and regulatory role phosphatases play in transcription. We now know that CTD phosphatases ensure the proper transition between different stages of transcription, balance the distribution of phosphorylation for accurate termination and re-initiation, and prevent inappropriate expression of certain genes. In this review, we focus on the specific roles of CTD phosphatases in regulating transcription. In particular, we emphasize how specificity and timing of dephosphorylation are achieved for these phosphatases and consider the various regulatory factors that affect these dynamics.
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Affiliation(s)
- Joshua E Mayfield
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Nathaniel T Burkholder
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Yan Jessie Zhang
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
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13
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Samofalova DA, Karpov PA, Blume YB. Bioinformatic comparison of human and higher plant phosphatomes. CYTOL GENET+ 2015. [DOI: 10.3103/s0095452715040088] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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14
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Srivastava R, Ahn SH. Modifications of RNA polymerase II CTD: Connections to the histone code and cellular function. Biotechnol Adv 2015; 33:856-72. [PMID: 26241863 DOI: 10.1016/j.biotechadv.2015.07.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 07/08/2015] [Accepted: 07/28/2015] [Indexed: 12/24/2022]
Abstract
At the onset of transcription, many protein machineries interpret the cellular signals that regulate gene expression. These complex signals are mostly transmitted to the indispensable primary proteins involved in transcription, RNA polymerase II (RNAPII) and histones. RNAPII and histones are so well coordinated in this cellular function that each cellular signal is precisely allocated to specific machinery depending on the stage of transcription. The carboxy-terminal domain (CTD) of RNAPII in eukaryotes undergoes extensive posttranslational modification, called the 'CTD code', that is indispensable for coupling transcription with many cellular processes, including mRNA processing. The posttranslational modification of histones, known as the 'histone code', is also critical for gene transcription through the reversible and dynamic remodeling of chromatin structure. Notably, the histone code is closely linked with the CTD code, and their combinatorial effects enable the delicate regulation of gene transcription. This review elucidates recent findings regarding the CTD modifications of RNAPII and their coordination with the histone code, providing integrative pathways for the fine-tuned regulation of gene expression and cellular function.
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Affiliation(s)
- Rakesh Srivastava
- Division of Molecular and Life Sciences, College of Science and Technology, Hanyang University, Ansan, Republic of Korea
| | - Seong Hoon Ahn
- Division of Molecular and Life Sciences, College of Science and Technology, Hanyang University, Ansan, Republic of Korea.
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15
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Koo J, Bahk YY. In vivo putative O-GlcNAcylation of human SCP1 and evidence for possible role of its N-terminal disordered structure. BMB Rep 2015; 47:593-8. [PMID: 25081999 PMCID: PMC4261519 DOI: 10.5483/bmbrep.2014.47.10.144] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Indexed: 11/20/2022] Open
Abstract
RNA polymerase II carboxyl-terminal domain (RNAPII CTD) phosphatases are responsible for the dephosphorylation of the C-terminal domain of the small subunit of RNAPII in eukaryotes. Recently, we demonstrated the identification of several interacting partners with human small CTD phosphatase1 (hSCP1) and the substrate specificity to delineate an appearance of the dephosphorylation catalyzed by SCP1. In this study, using the established cells for inducibly expressing hSCP1 proteins, we monitored the modification of β-O-linked N-acetylglucosamine (O-GlcNAc). O-GlcNAcylation is one of the most common post-translational modifications (PTMs). To gain insight into the PTM of hSCP1, we used the Western blot, immunoprecipitation, succinylayed wheat germ agglutininprecipitation, liquid chromatography-mass spectrometry analyses, and site-directed mutagenesis and identified the Ser41 residue of hSCP1 as the O-GlcNAc modification site. These results suggest that hSCP1 may be an O-GlcNAcylated protein in vivo, and its N-terminus may function a possible role in the PTM, providing a scaffold for binding the protein(s). [BMB Reports 2014; 47(10): 593-598]
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Affiliation(s)
- JaeHyung Koo
- Department of Brain Science, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873, Korea
| | - Young Yil Bahk
- Department of Biotechnology, Konkuk University, Chungju 380-701, Korea
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16
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Immormino RM, Starbird CA, Silversmith RE, Bourret RB. Probing Mechanistic Similarities between Response Regulator Signaling Proteins and Haloacid Dehalogenase Phosphatases. Biochemistry 2015; 54:3514-27. [PMID: 25928369 DOI: 10.1021/acs.biochem.5b00286] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Response regulator signaling proteins and phosphatases of the haloacid dehalogenase (HAD) superfamily share strikingly similar folds, active site geometries, and reaction chemistry. Proteins from both families catalyze the transfer of a phosphoryl group from a substrate to one of their own aspartyl residues, and subsequent hydrolysis of the phosphoprotein. Notable differences include an additional Asp that functions as an acid/base catalyst and an active site well-structured prior to phosphorylation in HAD phosphatases. Both features contribute to reactions substantially faster than those for response regulators. To investigate mechanisms underlying the functional differences between response regulators and HAD phosphatases, we characterized five double mutants of the response regulator CheY designed to mimic HAD phosphatases. Each mutant contained the extra Asp paired with a phosphatase-inspired substitution to potentially position the Asp properly. Only CheY DR (Arg as the anchor) exhibited enhanced rates of both autophosphorylation with phosphoramidate and autodephosphorylation compared to those of wild-type CheY. Crystal structures of CheY DR complexed with MoO4(2-) or WO4(2-) revealed active site hydrogen bonding networks similar to those in HAD·substrate complexes, with the extra Asp positioned for direct interaction with the leaving group (phosphorylation) or nucleophile (dephosphorylation). However, CheY DR reaction kinetics did not exhibit the pH sensitivities expected for acid/base catalysis. Biochemical analysis indicated CheY DR had an enhanced propensity to adopt the active conformation without phosphorylation, but a crystal structure revealed unphosphorylated CheY DR was not locked in the active conformation. Thus, the enhanced reactivity of CheY DR reflected partial acquisition of catalytic and structural features of HAD phosphatases.
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Affiliation(s)
- Robert M Immormino
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599-7290, United States
| | - Chrystal A Starbird
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599-7290, United States
| | - Ruth E Silversmith
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599-7290, United States
| | - Robert B Bourret
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599-7290, United States
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17
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Winkelströter LK, Dolan SK, Fernanda Dos Reis T, Bom VLP, Alves de Castro P, Hagiwara D, Alowni R, Jones GW, Doyle S, Brown NA, Goldman GH. Systematic Global Analysis of Genes Encoding Protein Phosphatases in Aspergillus fumigatus. G3 (BETHESDA, MD.) 2015; 5:1525-39. [PMID: 25943523 PMCID: PMC4502386 DOI: 10.1534/g3.115.016766] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/30/2015] [Indexed: 11/18/2022]
Abstract
Aspergillus fumigatus is a fungal pathogen that causes several invasive and noninvasive diseases named aspergillosis. This disease is generally regarded as multifactorial, considering that several pathogenicity determinants are present during the establishment of this illness. It is necessary to obtain an increased knowledge of how, and which, A. fumigatus signal transduction pathways are engaged in the regulation of these processes. Protein phosphatases are essential to several signal transduction pathways. We identified 32 phosphatase catalytic subunit-encoding genes in A. fumigatus, of which we were able to construct 24 viable deletion mutants. The role of nine phosphatase mutants in the HOG (high osmolarity glycerol response) pathway was evaluated by measuring phosphorylation of the p38 MAPK (SakA) and expression of osmo-dependent genes. We were also able to identify 11 phosphatases involved in iron assimilation, six that are related to gliotoxin resistance, and three implicated in gliotoxin production. These results present the creation of a fundamental resource for the study of signaling in A. fumigatus and its implications in the regulation of pathogenicity determinants and virulence in this important pathogen.
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Affiliation(s)
- Lizziane K Winkelströter
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 13083-970 Ribeirão Preto, Brazil
| | - Stephen K Dolan
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Thaila Fernanda Dos Reis
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 13083-970 Ribeirão Preto, Brazil
| | - Vinícius Leite Pedro Bom
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 13083-970 Ribeirão Preto, Brazil
| | - Patrícia Alves de Castro
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 13083-970 Ribeirão Preto, Brazil
| | - Daisuke Hagiwara
- Medical Mycology Research Center, Chiba University, Chiba 260-8673, Japan
| | - Raneem Alowni
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Gary W Jones
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Sean Doyle
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Neil Andrew Brown
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 13083-970 Ribeirão Preto, Brazil
| | - Gustavo H Goldman
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 13083-970 Ribeirão Preto, Brazil National Laboratory of Science and Technology of Bioethanol (CTBE), 13083-970 Campinas, Brazil
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18
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Wang W, Liao P, Shen M, Chen T, Chen Y, Li Y, Lin X, Ge X, Wang P. SCP1 regulates c-Myc stability and functions through dephosphorylating c-Myc Ser62. Oncogene 2015; 35:491-500. [PMID: 25893300 DOI: 10.1038/onc.2015.106] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 01/28/2015] [Accepted: 02/27/2015] [Indexed: 02/06/2023]
Abstract
Serine 62 (Ser62) phosphorylation affects the c-Myc protein stability in cancer cells. However, the mechanism for dephosphorylating c-Myc is not well understood. In this study, we identified carboxyl-terminal domain RNA polymerase II polypeptide A small phosphatase 1 (SCP1) as a novel phosphatase specifically dephosphorylating c-Myc Ser62. Ectopically expressed SCP1 strongly dephosphorylated c-Myc Ser62, destabilized c-Myc protein and suppressed c-Myc transcriptional activity. Knockdown of SCP1 increased the c-Myc protein levels in liver cancer cells. SCP1 interacted with c-Myc both in vivo and in vitro. In addition, Ser245 at the C-terminus of SCP1 was essential for its phosphatase activity towards c-Myc. Functionally, SCP1 negatively regulated the cancer cell proliferation. Collectively, our findings indicate that SCP1 is a potential tumor suppressor for liver cancers through dephosphorylating c-Myc Ser62.
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Affiliation(s)
- W Wang
- Department of Central Laboratory, Shanghai 10th People's Hospital, Tongji University, Shanghai, China.,Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - P Liao
- Department of Central Laboratory, Shanghai 10th People's Hospital, Tongji University, Shanghai, China.,Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - M Shen
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - T Chen
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Y Chen
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Y Li
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - X Lin
- Department of Surgery, Baylor College of Medicine, Houston, TX, USA
| | - X Ge
- Department of Central Laboratory, Shanghai 10th People's Hospital, Tongji University, Shanghai, China
| | - P Wang
- Department of Central Laboratory, Shanghai 10th People's Hospital, Tongji University, Shanghai, China.,Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China.,School of Life Science and Technology, Tongji University, Shanghai, China
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19
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He Y, Guo X, Yu ZH, Wu L, Gunawan AM, Zhang Y, Dixon JE, Zhang ZY. A potent and selective inhibitor for the UBLCP1 proteasome phosphatase. Bioorg Med Chem 2015; 23:2798-809. [PMID: 25907364 DOI: 10.1016/j.bmc.2015.03.066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/23/2015] [Accepted: 03/24/2015] [Indexed: 11/17/2022]
Abstract
The ubiquitin-like domain-containing C-terminal domain phosphatase 1 (UBLCP1) has been implicated as a negative regulator of the proteasome, a key mediator in the ubiquitin-dependent protein degradation. Small molecule inhibitors that block UBLCP1 activity would be valuable as research tools and potential therapeutics for human diseases caused by the cellular accumulation of misfold/damaged proteins. We report a salicylic acid fragment-based library approach aimed at targeting both the phosphatase active site and its adjacent binding pocket for enhanced affinity and selectivity. Screening of the focused libraries led to the identification of the first potent and selective UBLCP1 inhibitor 13. Compound 13 exhibits an IC50 of 1.0μM for UBLCP1 and greater than 5-fold selectivity against a large panel of protein phosphatases from several distinct families. Importantly, the inhibitor possesses efficacious cellular activity and is capable of inhibiting UBLCP1 function in cells, which in turn up-regulates nuclear proteasome activity. These studies set the groundwork for further developing compound 13 into chemical probes or potential therapeutic agents targeting the UBLCP1 phosphatase.
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Affiliation(s)
- Yantao He
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202, USA
| | - Xing Guo
- Department of Pharmacology, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Zhi-Hong Yu
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202, USA
| | - Li Wu
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202, USA
| | - Andrea M Gunawan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202, USA
| | - Yan Zhang
- Department of Chemistry and Biochemistry, The University of Texas at Austin, 1 University Station A5300, Austin, TX 78712, USA
| | - Jack E Dixon
- Department of Pharmacology, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Cellular and Molecular Medicine, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Chemistry and Biochemistry, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Zhong-Yin Zhang
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202, USA.
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20
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R HR, Kim H, Noh K, Kim YJ. The diverse roles of RNA polymerase II C-terminal domain phosphatase SCP1. BMB Rep 2015; 47:192-6. [PMID: 24755554 PMCID: PMC4163886 DOI: 10.5483/bmbrep.2014.47.4.060] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Indexed: 11/20/2022] Open
Abstract
RNA polymerase II carboxyl-terminal domain (pol II CTD) phosphatases are a newly emerging family of phosphatases that are members of DXDX (T/V). The subfamily includes Small CTD phosphatases, like SCP1, SCP2, SCP3, TIMM50, HSPC129 and UBLCP. Extensive study of SCP1 has elicited the diversified roles of the small C terminal domain phosphatase. The SCP1 plays a vital role in various biological activities, like neuronal gene silencing and preferential Ser5 dephosphorylation, acts as a cardiac hypertrophy inducer with the help of its intronic miRNAs, and has shown a key role in cell cycle regulation. This short review offers an explanation of the mechanism of action of small CTD phosphatases, in different biological activities and metabolic processes. [BMB Reports 2014; 47(4): 192-196]
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Affiliation(s)
- Harikrishna Reddy R
- Departments of Applied Biochemistry Research Center, Konkuk University, Chungju 380-701, Korea
| | - Hackyoung Kim
- Departments of Applied Biochemistry Research Center, Konkuk University, Chungju 380-701, Korea
| | - Kwangmo Noh
- Departments of Nanotechnology Research Center, Konkuk University, Chungju 380-701, Korea
| | - Young Jun Kim
- Departments of Applied Biochemistry and Nanotechnology Research Center, Konkuk University, Chungju 380-701, Korea
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21
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Winkelströter LK, Bom VLP, de Castro PA, Ramalho LNZ, Goldman MHS, Brown NA, Rajendran R, Ramage G, Bovier E, Dos Reis TF, Savoldi M, Hagiwara D, Goldman GH. High osmolarity glycerol response PtcB phosphatase is important for Aspergillus fumigatus virulence. Mol Microbiol 2015; 96:42-54. [PMID: 25597841 DOI: 10.1111/mmi.12919] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/26/2014] [Indexed: 12/11/2022]
Abstract
Aspergillus fumigatus is a fungal pathogen that is capable of adapting to different host niches and to avoid host defenses. An enhanced understanding of how, and which, A. fumigatus signal transduction pathways are engaged in the regulation of these processes is essential for the development of improved disease control strategies. Protein phosphatases are central to numerous signal transduction pathways. To comprehend the functions of protein phosphatases in A. fumigatus, 32 phosphatase catalytic subunit encoding genes were identified. We have recognized PtcB as one of the phosphatases involved in the high osmolarity glycerol response (HOG) pathway. The ΔptcB mutant has both increased phosphorylation of the p38 MAPK (SakA) and expression of osmo-dependent genes. The ΔptcB strain was more sensitive to cell wall damaging agents, had increased chitin and β-1,3-glucan, and impaired biofilm formation. The ΔptcB strain was avirulent in a murine model of invasive pulmonary aspergillosis. These results stress the importance of the HOG pathway in the regulation of pathogenicity determinants and virulence in A. fumigatus.
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Affiliation(s)
- Lizziane K Winkelströter
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
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22
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Jaramillo-Tatis S, Bamm VV, Vassall KA, Harauz G. Over-expression in E. coli and purification of functional full-length murine small C-terminal domain phosphatase (SCP1, or Golli-interacting protein). Protein Expr Purif 2014; 101:106-14. [PMID: 24925644 DOI: 10.1016/j.pep.2014.05.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 05/26/2014] [Accepted: 05/31/2014] [Indexed: 01/13/2023]
Abstract
During myelination in the central nervous system, proteins arising from the gene in the oligodendrocyte lineage (golli) participate in diverse events in signal transduction and gene regulation. One of the interacting partners of the Golli-isoform BG21 was discovered by yeast-2-hybrid means and was denoted the Golli-interacting-protein (GIP). In subsequent in vitro studies of recombinant murine GIP, it was not possible to produce a full-length version of recombinant murine rmGIP in functional form under native conditions, primarily because of solubility issues, necessitating the study of a hexahistidine-tagged, truncated form ΔN-rmGIP. This protein is an acidic phosphatase belonging to the family of RNA-polymerase-2, small-subunit, C-terminal phosphatases (SCP1), and studies of the human ortholog hSCP1 have also been performed on truncated forms. Here, a new SUMO-expression and purification protocol has been developed for the preparation of a functional, full-length mSCP1/GIP (our nomenclature henceforth), with no additional purification tags. Both full-length mSCP1/GIP and the truncated murine form (now denoted ΔN-rmSCP1/GIP) had similar melting temperatures, indicating that the integrity of the catalytic core per se was minimally affected by the N-terminus. Characterization of mSCP1/GIP activity with the artificial substrate p-NPP (p-nitrophenylphosphate) yielded kinetic parameters comparable to those of ΔN-rmSCP1/GIP and the truncated human ortholog ΔN-hSCP1. Similarly, mSCP1/GIP dephosphorylated a more natural CTD-peptide substrate (but not protein kinase C-phosphorylated BG21) with comparable kinetics to ΔN-hSCP1. The successful production of an active, full-length mSCP1/GIP will enable future evaluation of the functional role of its N-terminus in protein-protein interactions (e.g., BG21) that regulate its phosphatase activity.
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Affiliation(s)
- Sergio Jaramillo-Tatis
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada
| | - Vladimir V Bamm
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada
| | - Kenrick A Vassall
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada
| | - George Harauz
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada.
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23
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Jaramillo-Tatis S, Vassall KA, Bamm VV, Harauz G. Regulatory effect of the glial Golli-BG21 protein on the full-length murine small C-terminal domain phosphatase (SCP1, or Golli-interacting protein). Biochem Biophys Res Commun 2014; 447:633-7. [PMID: 24751520 DOI: 10.1016/j.bbrc.2014.04.050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 04/10/2014] [Indexed: 12/12/2022]
Abstract
The gene in the oligodendrocyte lineage (golli) encodes a number of proteins essential for myelination, comprising Golli and classic isoforms that are expressed in a developmentally-regulated manner. The Golli-interacting-protein (GIP) was previously discovered in a search for potential interacting partners of the Golli-isoform BG21, and was realised to be an acidic phosphatase belonging to the family of RNA-polymerase-2, small-subunit, C-terminal phosphatases (viz., SCP1). Here, we refer to this protein as mSCP1/GIP. In subsequent in vitro studies of recombinant murine SCP1/GIP, the inability to produce an active full-length version of the protein under native conditions necessitated the study of a truncated form ΔN-rmSCP1/GIP, but with inconclusive results regarding its interaction with BG21 [13]. We have since developed a new SUMO-expression and purification protocol for the preparation of a functional, full-length mGIP/SCP1, with no additional purification tags. Here, the interaction between mSCP1/GIP (with intact N-terminus) and BG21 is shown to be different than for the truncation mutant studied previously. Specifically, this interaction shows a dual effect on the enzymatic activity of mSCP1/GIP by BG21: BG21 enhanced mSCP1/GIP phosphatase activity (Ka = 30 μM), whereas PKCα-phosphorylated BG21 inhibited its activity (Ki = 2.9 μM), suggesting a potential role of BG21 as a molecular switch ("quick-brake mechanism") on mSCP1/GIP. The successful production of an active, full-length mSCP1/GIP thus demonstrates a role for its N-terminus in regulation of phosphatase activity, in events such as the regulation of transcription in oligodendrocytes.
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Affiliation(s)
- Sergio Jaramillo-Tatis
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada
| | - Kenrick A Vassall
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada
| | - Vladimir V Bamm
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada
| | - George Harauz
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada.
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24
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Global analysis of serine/threonine and tyrosine protein phosphatase catalytic subunit genes in Neurospora crassa reveals interplay between phosphatases and the p38 mitogen-activated protein kinase. G3-GENES GENOMES GENETICS 2014; 4:349-65. [PMID: 24347630 PMCID: PMC3931568 DOI: 10.1534/g3.113.008813] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Protein phosphatases are integral components of the cellular signaling machinery in eukaryotes, regulating diverse aspects of growth and development. The genome of the filamentous fungus and model organism Neurospora crassa encodes catalytic subunits for 30 protein phosphatase genes. In this study, we have characterized 24 viable N. crassa phosphatase catalytic subunit knockout mutants for phenotypes during growth, asexual development, and sexual development. We found that 91% of the mutants had defects in at least one of these traits, whereas 29% possessed phenotypes in all three. Chemical sensitivity screens were conducted to reveal additional phenotypes for the mutants. This resulted in the identification of at least one chemical sensitivity phenotype for 17 phosphatase knockout mutants, including novel chemical sensitivities for two phosphatase mutants lacking a growth or developmental phenotype. Hence, chemical sensitivity or growth/developmental phenotype was observed for all 24 viable mutants. We investigated p38 mitogen-activated protein kinase (MAPK) phosphorylation profiles in the phosphatase mutants and identified nine potential candidates for regulators of the p38 MAPK. We demonstrated that the PP2C class phosphatase pph-8 (NCU04600) is an important regulator of female sexual development in N. crassa. In addition, we showed that the Δcsp-6 (ΔNCU08380) mutant exhibits a phenotype similar to the previously identified conidial separation mutants, Δcsp-1 and Δcsp-2, that lack transcription factors important for regulation of conidiation and the circadian clock.
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25
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Cross-talk of phosphorylation and prolyl isomerization of the C-terminal domain of RNA Polymerase II. Molecules 2014; 19:1481-511. [PMID: 24473209 PMCID: PMC4350670 DOI: 10.3390/molecules19021481] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 01/06/2014] [Accepted: 01/21/2014] [Indexed: 12/04/2022] Open
Abstract
Post-translational modifications of the heptad repeat sequences in the C-terminal domain (CTD) of RNA polymerase II (Pol II) are well recognized for their roles in coordinating transcription with other nuclear processes that impinge upon transcription by the Pol II machinery; and this is primarily achieved through CTD interactions with the various nuclear factors. The identification of novel modifications on new regulatory sites of the CTD suggests that, instead of an independent action for all modifications on CTD, a combinatorial effect is in operation. In this review we focus on two well-characterized modifications of the CTD, namely serine phosphorylation and prolyl isomerization, and discuss the complex interplay between the enzymes modifying their respective regulatory sites. We summarize the current understanding of how the prolyl isomerization state of the CTD dictates the specificity of writers (CTD kinases), erasers (CTD phosphatases) and readers (CTD binding proteins) and how that correlates to transcription status. Subtle changes in prolyl isomerization states cannot be detected at the primary sequence level, we describe the methods that have been utilized to investigate this mode of regulation. Finally, a general model of how prolyl isomerization regulates the phosphorylation state of CTD, and therefore transcription-coupled processes, is proposed.
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26
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Zhang M, Yogesha SD, Mayfield JE, Gill GN, Zhang Y. Viewing serine/threonine protein phosphatases through the eyes of drug designers. FEBS J 2013; 280:4739-60. [PMID: 23937612 DOI: 10.1111/febs.12481] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 07/03/2013] [Accepted: 08/02/2013] [Indexed: 01/04/2023]
Abstract
Protein phosphatases, as the counterpart to protein kinases, are essential for homeostatic balance of cell signaling. Small chemical compounds that modulate the specific activity of phosphatases can be powerful tools to elucidate the biological functions of these enzymes. More importantly, many phosphatases are central players in the development of pathological pathways where inactivation can reverse or delay the onset of human diseases. Therefore, potent inhibitors for such phosphatases can be of great therapeutic benefit. In contrast to the seemingly identical enzymatic mechanism and structural characterization of eukaryotic protein kinases, protein phosphatases evolved from diverse ancestors, resulting in different domain architectures, reaction mechanisms and active site properties. In this review, we discuss for each family of serine/threonine protein phosphatases their involvement in biological processes and corresponding strategies for small chemical intervention. Recent advances in modern drug discovery technologies have markedly facilitated the identification of selective inhibitors for some members of the phosphatase family. Furthermore, the rapid growth in knowledge about structure-activity relationships related to possible new drug targets has aided the discovery of natural product inhibitors for the phosphatase family. This review summarizes the current state of investigation of the small molecules that regulate the function of serine/threonine phosphatases, the challenges presented and also strategies to overcome these obstacles.
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Affiliation(s)
- Mengmeng Zhang
- Department of Chemistry and Biochemistry, University of Texas at Austin, TX, USA
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27
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Burns KE, McAllister FE, Schwerdtfeger C, Mintseris J, Cerda-Maira F, Noens EE, Wilmanns M, Hubbard SR, Melandri F, Ovaa H, Gygi SP, Darwin KH. Mycobacterium tuberculosis prokaryotic ubiquitin-like protein-deconjugating enzyme is an unusual aspartate amidase. J Biol Chem 2012; 287:37522-9. [PMID: 22942282 DOI: 10.1074/jbc.m112.384784] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Deamidase of Pup (Dop), the prokaryotic ubiquitin-like protein (Pup)-deconjugating enzyme, is critical for the full virulence of Mycobacterium tuberculosis and is unique to bacteria, providing an ideal target for the development of selective chemotherapies. We used a combination of genetics and chemical biology to characterize the mechanism of depupylation. We identified an aspartate as a potential nucleophile in the active site of Dop, suggesting a novel protease activity to target for inhibitor development.
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Affiliation(s)
- Kristin E Burns
- Department of Microbiology, New York University, New York, New York 10016, USA
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28
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Zhang M, Wang XJ, Chen X, Bowman ME, Luo Y, Noel JP, Ellington AD, Etzkorn FA, Zhang Y. Structural and kinetic analysis of prolyl-isomerization/phosphorylation cross-talk in the CTD code. ACS Chem Biol 2012; 7:1462-70. [PMID: 22670809 DOI: 10.1021/cb3000887] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The C-terminal domain (CTD) of eukaryotic RNA polymerase II is an essential regulator for RNA polymerase II-mediated transcription. It is composed of multiple repeats of a consensus sequence Tyr(1)Ser(2)Pro(3)Thr(4)Ser(5)Pro(6)Ser(7). CTD regulation of transcription is mediated by both phosphorylation of the serines and prolyl isomerization of the two prolines. Interestingly, the phosphorylation sites are typically close to prolines, and thus the conformation of the adjacent proline could impact the specificity of the corresponding kinases and phosphatases. Experimental evidence of cross-talk between these two regulatory mechanisms has been elusive. Pin1 is a highly conserved phosphorylation-specific peptidyl-prolyl isomerase (PPIase) that recognizes the phospho-Ser/Thr (pSer/Thr)-Pro motif with CTD as one of its primary substrates in vivo. In the present study, we provide structural snapshots and kinetic evidence that support the concept of cross-talk between prolyl isomerization and phosphorylation. We determined the structures of Pin1 bound with two substrate isosteres that mimic peptides containing pSer/Thr-Pro motifs in cis or trans conformations. The results unequivocally demonstrate the utility of both cis- and trans-locked alkene isosteres as close geometric mimics of peptides bound to a protein target. Building on this result, we identified a specific case in which Pin1 differentially affects the rate of dephosphorylation catalyzed by two phosphatases (Scp1 and Ssu72) that target the same serine residue in the CTD heptad repeat but have different preferences for the isomerization state of the adjacent proline residue. These data exemplify for the first time how modulation of proline isomerization can kinetically impact signal transduction in transcription regulation.
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Affiliation(s)
- Mengmeng Zhang
- Department
of Chemistry and
Biochemistry, University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712, United States
| | - Xiaodong J. Wang
- Department of Chemistry, Virginia Tech, MC 0212, Blacksburg, Virginia 24061,
United States
| | - Xi Chen
- Department
of Chemistry and
Biochemistry, University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712, United States
| | - Marianne E. Bowman
- Jack Skirball Chemical Biology
and Protein Laboratory, The Salk Institute, 10010 N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - Yonghua Luo
- Department
of Chemistry and
Biochemistry, University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712, United States
| | - Joseph P. Noel
- Jack Skirball Chemical Biology
and Protein Laboratory, The Salk Institute, 10010 N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - Andrew D. Ellington
- Department
of Chemistry and
Biochemistry, University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712, United States
| | - Felicia A. Etzkorn
- Department of Chemistry, Virginia Tech, MC 0212, Blacksburg, Virginia 24061,
United States
| | - Yan Zhang
- Department
of Chemistry and
Biochemistry, University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712, United States
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29
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Krueger AB, Dehdashti SJ, Southall N, Marugan JJ, Ferrer M, Li X, Ford HL, Zheng W, Zhao R. Identification of a selective small-molecule inhibitor series targeting the eyes absent 2 (Eya2) phosphatase activity. ACTA ACUST UNITED AC 2012; 18:85-96. [PMID: 22820394 DOI: 10.1177/1087057112453936] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Eya proteins are essential coactivators of the Six family of homeobox transcription factors and also contain a unique protein tyrosine phosphatase activity, belonging to the haloacid dehalogenase family of phosphatases. The phosphatase activity of Eya is important for a subset of Six1-mediated transcription, making this a unique type of transcriptional control. It is also responsible for directing cells to the repair instead of apoptosis pathway upon DNA damage. Furthermore, the phosphatase activity of Eya is critical for transformation, migration, invasion, and metastasis of breast cancer cells. Thus, inhibitors of the Eya phosphatase activity may be antitumorigenic and antimetastatic, as well as sensitize cancer cells to DNA damage-inducing therapies. In this article, we identified a previously unknown chemical series using high-throughput screening that inhibits the Eya2 phosphatase activity with IC(50)s ranging from 1.8 to 79 µM. Compound activity was confirmed using an alternative malachite green assay and H2AX, a known Eya substrate. Importantly, these Eya2 phosphatase inhibitors show specificity and do not significantly inhibit several other cellular phosphatases. Our studies identify the first selective Eya2 phosphatase inhibitors that can potentially be developed into chemical probes for functional studies of Eya phosphatase or into anticancer drugs in the future.
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Affiliation(s)
- Aaron B Krueger
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - Seameen J Dehdashti
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892
| | - Noel Southall
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892
| | - Juan J Marugan
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892
| | - Marc Ferrer
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892
| | - Xueni Li
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - Heide L Ford
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045.,Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045.,Department of Ob/Gyn, University of Colorado School of Medicine, Aurora, CO 80045
| | - Wei Zheng
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892
| | - Rui Zhao
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
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30
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Seifried A, Schultz J, Gohla A. Human HAD phosphatases: structure, mechanism, and roles in health and disease. FEBS J 2012; 280:549-71. [PMID: 22607316 DOI: 10.1111/j.1742-4658.2012.08633.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Phosphatases of the haloacid dehalogenase (HAD) superfamily of hydrolases are an ancient and very large class of enzymes that have evolved to dephosphorylate a wide range of low- and high molecular weight substrates with often exquisite specificities. HAD phosphatases constitute approximately one-fifth of all human phosphatase catalytic subunits. While the overall sequence similarity between HAD phosphatases is generally very low, family members can be identified based on the presence of a characteristic Rossmann-like fold and the active site sequence DxDx(V/T). HAD phosphatases employ an aspartate residue as a nucleophile in a magnesium-dependent phosphoaspartyl transferase reaction. Although there is genetic evidence demonstrating a causal involvement of some HAD phosphatases in diseases such as cancer, cardiovascular, metabolic and neurological disorders, the physiological roles of many of these enzymes are still poorly understood. In this review, we discuss the structure and evolution of human HAD phosphatases, and summarize their known functions in health and disease.
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Affiliation(s)
- Annegrit Seifried
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
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31
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Zhang M, Cho EJ, Burstein G, Siegel D, Zhang Y. Selective inactivation of a human neuronal silencing phosphatase by a small molecule inhibitor. ACS Chem Biol 2011; 6:511-9. [PMID: 21348431 DOI: 10.1021/cb100357t] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The unstructured C-terminal domain (CTD) of eukaryotic RNA polymerase II dynamically regulates the process of transcription by recruiting different factors to nascent mRNA through its multiple phosphorylation patterns. A newly discovered class of phosphatases, the human small C-terminal domain phosphatases (Scp's), specifically dephosphorylates phosphorylated Ser(5) (phospho.Ser5) of the tandem heptad repeats of the CTD of RNA polymerase II. Scp's also function as transcription regulators that epigenetically silence the expression of specific neuronal genes, whose inactivation leads to neuronal stem cell differentiation. Small molecule inhibitors of Scp's will be valuable for elucidating their mechanism in nervous system development and can possibly offer new strategies to treat diseases related to neurodegeneration. Despite the difficulty in developing selective inhibitors of protein phosphatases, we have recognized a characteristic hydrophobic binding pocket adjacent to the active site in Scp's that may facilitate selective inhibition. In the present study, we successfully identified the first selective lead compound, rabeprazole, for the Scp/TFIIF-interacting CTD phosphatase (Fcp) family. The high-resolution crystal structure of rabeprazole-bound Scp1 showed that the compound indeed binds to the hydrophobic binding pocket. We further confirmed that rabeprazole only targets Scp's but not its close family members Fcp1 and Dullard or bacteriophage λ Ser/Thr phosphatase. Such specificity may prove important for In Vivo studies since accidental inhibition of Fcp1 or Dullard would result in cell malfunctions and even cell death.
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Affiliation(s)
- Mengmeng Zhang
- Department of Chemistry and Biochemistry and ‡The Texas Institute for Drug and Diagnostic Development, University of Texas at Austin, Austin, Texas 78712, United States
| | - Eun Jeong Cho
- Department of Chemistry and Biochemistry and ‡The Texas Institute for Drug and Diagnostic Development, University of Texas at Austin, Austin, Texas 78712, United States
| | - Gayle Burstein
- Department of Chemistry and Biochemistry and ‡The Texas Institute for Drug and Diagnostic Development, University of Texas at Austin, Austin, Texas 78712, United States
| | - Dionicio Siegel
- Department of Chemistry and Biochemistry and ‡The Texas Institute for Drug and Diagnostic Development, University of Texas at Austin, Austin, Texas 78712, United States
| | - Yan Zhang
- Department of Chemistry and Biochemistry and ‡The Texas Institute for Drug and Diagnostic Development, University of Texas at Austin, Austin, Texas 78712, United States
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32
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Crystal structure of Ssu72, an essential eukaryotic phosphatase specific for the C-terminal domain of RNA polymerase II, in complex with a transition state analogue. Biochem J 2011; 434:435-44. [DOI: 10.1042/bj20101471] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Reversible phosphorylation of the CTD (C-terminal domain) of the eukaryotic RNA polymerase II largest subunit represents a critical regulatory mechanism during the transcription cycle and mRNA processing. Ssu72 is an essential phosphatase conserved in eukaryotes that dephosphorylates phosphorylated Ser5 of the CTD heptapeptide. Its function is implicated in transcription initiation, elongation and termination, as well as RNA processing. In the present paper we report the high resolution X-ray crystal structures of Drosophila melanogaster Ssu72 phosphatase in the apo form and in complex with an inhibitor mimicking the transition state of phosphoryl transfer. Ssu72 facilitates dephosphorylation of the substrate through a phosphoryl-enzyme intermediate, as visualized in the complex structure of Ssu72 with the oxo-anion compound inhibitor vanadate at a 2.35 Å (1 Å=0.1 nm) resolution. The structure resembles the transition state of the phosphoryl transfer with vanadate exhibiting a trigonal bi-pyramidal geometry covalently bonded to the nucleophilic cysteine residue. Interestingly, the incorporation of oxo-anion compounds greatly stabilizes a flexible loop containing the general acid, as detected by an increase of melting temperature of Ssu72 detected by differential scanning fluorimetry. The Ssu72 structure exhibits a core fold with a similar topology to that of LMWPTPs [low-molecular-mass PTPs (protein tyrosine phosphatases)], but with an insertion of a unique ‘cap’ domain to shelter the active site from the solvent with a deep groove in between where the CTD substrates bind. Mutagenesis studies in this groove established the functional roles of five residues (Met17, Pro46, Asp51, Tyr77 and Met85) that are essential specifically for substrate recognition.
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33
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Zhang M, Gill GN, Zhang Y. Bio-molecular architects: a scaffold provided by the C-terminal domain of eukaryotic RNA polymerase II. NANO REVIEWS 2010; 1:NANO-1-5502. [PMID: 22110856 PMCID: PMC3215212 DOI: 10.3402/nano.v1i0.5502] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 07/30/2010] [Accepted: 08/03/2010] [Indexed: 11/14/2022]
Abstract
In eukaryotic cells, the transcription of genes is accurately orchestrated both spatially and temporally by the C-terminal domain of RNA polymerase II (CTD). The CTD provides a dynamic platform to recruit different regulators of the transcription apparatus. Different posttranslational modifications are precisely applied to specific sites of the CTD to coordinate transcription process. Regulators of the RNA polymerase II must identify specific sites in the CTD for cellular survival, metabolism, and development. Even though the CTD is disordered in the eukaryotic RNA polymerase II crystal structures due to its intrinsic flexibility, recent advances in the complex structural analysis of the CTD with its binding partners provide essential clues for understanding how selectivity is achieved for individual site recognition. The recent discoveries of the interactions between the CTD and histone modification enzymes disclose an important role of the CTD in epigenetic control of the eukaryotic gene expression. The intersection of the CTD code with the histone code discloses an intriguing yet complicated network for eukaryotic transcriptional regulation.
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Affiliation(s)
- Mengmeng Zhang
- Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX, USA
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