1
|
Zhang Q, Kim W, Panina S, Mayfield JE, Portz B, Zhang YJ. Variation of C-terminal domain governs RNA polymerase II genomic locations and alternative splicing in eukaryotic transcription. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.01.573828. [PMID: 38260389 PMCID: PMC10802280 DOI: 10.1101/2024.01.01.573828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The C-terminal domain of RPB1 (CTD) orchestrates transcription by recruiting regulators to RNA Pol II upon phosphorylation. Recent insights highlight the pivotal role of CTD in driving condensate formation on gene loci. Yet, the molecular mechanism behind how CTD-mediated recruitment of transcriptional regulators influences condensates formation remains unclear. Our study unveils that phosphorylation reversibly dissolves phase separation induced by the unphosphorylated CTD. Phosphorylated CTD, upon specific association with transcription regulatory proteins, forms distinct condensates from unphosphorylated CTD. Function studies demonstrate CTD variants with diverse condensation properties in vitro exhibit difference in promoter binding and mRNA co-processing in cells. Notably, varying CTD lengths lead to alternative splicing outcomes impacting cellular growth, linking the evolution of CTD variation/length with the complexity of splicing from yeast to human. These findings provide compelling evidence for a model wherein post-translational modification enables the transition of functionally specialized condensates, highlighting a co-evolution link between CTD condensation and splicing.
Collapse
Affiliation(s)
- Qian Zhang
- Department of Molecular Biosciences, University of Texas, Austin, Texas, 78712
| | - Wantae Kim
- McKetta Department of Chemical Engineering, University of Texas, Austin, Texas, 78712
| | - Svetlana Panina
- Department of Molecular Biosciences, University of Texas, Austin, Texas, 78712
| | - Joshua E. Mayfield
- Department of Pharmacology, Chemistry, and Biochemistry, and Cellular and Molecular Medicine, University of California San Diego, La Jolla, California 92093
| | - Bede Portz
- Dewpoint Therapeutics, 451 D Street, Boston, Massachusetts 02210
| | - Y. Jessie Zhang
- Department of Molecular Biosciences, University of Texas, Austin, Texas, 78712
| |
Collapse
|
2
|
Venkat Ramani MK, Yang W, Irani S, Zhang Y. Simplicity is the Ultimate Sophistication-Crosstalk of Post-translational Modifications on the RNA Polymerase II. J Mol Biol 2021; 433:166912. [PMID: 33676925 PMCID: PMC8184622 DOI: 10.1016/j.jmb.2021.166912] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/23/2021] [Accepted: 02/26/2021] [Indexed: 12/19/2022]
Abstract
The highly conserved C-terminal domain (CTD) of the largest subunit of RNA polymerase II comprises a consensus heptad (Y1S2P3T4S5P6S7) repeated multiple times. Despite the simplicity of its sequence, the essential CTD domain orchestrates eukaryotic transcription and co-transcriptional processes, including transcription initiation, elongation, and termination, and mRNA processing. These distinct facets of the transcription cycle rely on specific post-translational modifications (PTM) of the CTD, in which five out of the seven residues in the heptad repeat are subject to phosphorylation. A hypothesis termed the "CTD code" has been proposed in which these PTMs and their combinations generate a sophisticated landscape for spatiotemporal recruitment of transcription regulators to Pol II. In this review, we summarize the recent experimental evidence understanding the biological role of the CTD, implicating a context-dependent theme that significantly enhances the ability of accurate transcription by RNA polymerase II. Furthermore, feedback communication between the CTD and histone modifications coordinates chromatin states with RNA polymerase II-mediated transcription, ensuring the effective and accurate conversion of information into cellular responses.
Collapse
Affiliation(s)
| | - Wanjie Yang
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, United States
| | - Seema Irani
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, United States
| | - Yan Zhang
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, United States; The Institute for Cellular and Molecular Biology. University of Texas at Austin, Austin, TX 78712, United States.
| |
Collapse
|
3
|
Hwang S, Kim MH, Lee CW. Ssu72 Dual-Specific Protein Phosphatase: From Gene to Diseases. Int J Mol Sci 2021; 22:3791. [PMID: 33917542 PMCID: PMC8038829 DOI: 10.3390/ijms22073791] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/02/2021] [Accepted: 04/05/2021] [Indexed: 12/22/2022] Open
Abstract
More than 70% of eukaryotic proteins are regulated by phosphorylation. However, the mechanism of dephosphorylation that counteracts phosphorylation is less studied. Phosphatases are classified into 104 distinct groups based on substrate-specific features and the sequence homologies in their catalytic domains. Among them, dual-specificity phosphatases (DUSPs) that dephosphorylate both phosphoserine/threonine and phosphotyrosine are important for cellular homeostasis. Ssu72 is a newly studied phosphatase with dual specificity that can dephosphorylate both phosphoserine/threonine and phosphotyrosine. It is important for cell-growth signaling, metabolism, and immune activation. Ssu72 was initially identified as a phosphatase for the Ser5 and Ser7 residues of the C-terminal domain of RNA polymerase II. It prefers the cis configuration of the serine-proline motif within its substrate and regulates Pin1, different from other phosphatases. It has recently been reported that Ssu72 can regulate sister chromatid cohesion and the separation of duplicated chromosomes during the cell cycle. Furthermore, Ssu72 appears to be involved in the regulation of T cell receptor signaling, telomere regulation, and even hepatocyte homeostasis in response to a variety of stress and damage signals. In this review, we aim to summarize various functions of the Ssu72 phosphatase, their implications in diseases, and potential therapeutic indications.
Collapse
Affiliation(s)
- Soeun Hwang
- Department of Molecular Cell Biology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon 16419, Korea; (S.H.); (M.-H.K.)
| | - Min-Hee Kim
- Department of Molecular Cell Biology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon 16419, Korea; (S.H.); (M.-H.K.)
| | - Chang-Woo Lee
- Department of Molecular Cell Biology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon 16419, Korea; (S.H.); (M.-H.K.)
- SKKU Institute for Convergence, Sungkyunkwan University, Suwon 16419, Korea
- Curogen Technology, Suwon 16419, Korea
| |
Collapse
|
4
|
Liu C, Zhang W, Xing W. Diverse and conserved roles of the protein Ssu72 in eukaryotes: from yeast to higher organisms. Curr Genet 2020; 67:195-206. [PMID: 33244642 DOI: 10.1007/s00294-020-01132-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 11/04/2020] [Accepted: 11/06/2020] [Indexed: 01/21/2023]
Abstract
Gene transcription is a complex biological process that involves a set of factors, enzymes and nucleotides. Ssu72 plays a crucial role in every step of gene transcription. RNA polymerase II (RNAPII) occupies an important position in the synthesis of mRNAs. The largest subunit of RNAPII, Rpb1, harbors its C-terminal domain (CTD), which participates in the initiation, elongation and termination of transcription. The CTD consists of heptad repeats of the consensus motif Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7 and is highly conserved among different species. The CTD is flexible in structure and undergoes conformational changes in response to serine phosphorylation and proline isomerization, which are regulated by specific kinases/phosphatases and isomerases, respectively. Ssu72 is a CTD phosphatase with catalytic activity against phosphorylated Ser5 and Ser7. The isomerization of Pro6 affects the binding of Ssu72 to its substrate. Ssu72 can also indirectly change the phosphorylation status of Ser2. In addition, Ssu72 is a member of the 3'-end cleavage and polyadenylation factor (CPF) complex. Together with other CPF components, Ssu72 regulates the 3'-end processing of premature mRNA. Recent studies have revealed other roles of Ssu72, including its roles in balancing phosphate homeostasis and controlling chromosome behaviors, which should be further explored. In conclusion, the protein Ssu72 is an enzyme worthy of attention, not confined to its role in gene transcription.
Collapse
Affiliation(s)
- Changfu Liu
- Department of Interventional Treatment, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Tianjin's Clinical Research Center for Cancer, Tianjin, 300060, China
| | - Weihao Zhang
- Department of Interventional Treatment, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Tianjin's Clinical Research Center for Cancer, Tianjin, 300060, China
| | - Wenge Xing
- Department of Interventional Treatment, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Tianjin's Clinical Research Center for Cancer, Tianjin, 300060, China.
| |
Collapse
|
5
|
Irani S, Sipe SN, Yang W, Burkholder NT, Lin B, Sim K, Matthews WL, Brodbelt JS, Zhang Y. Structural determinants for accurate dephosphorylation of RNA polymerase II by its cognate C-terminal domain (CTD) phosphatase during eukaryotic transcription. J Biol Chem 2019; 294:8592-8605. [PMID: 30971428 DOI: 10.1074/jbc.ra119.007697] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 04/03/2019] [Indexed: 12/31/2022] Open
Abstract
The C-terminal domain (CTD) of RNA polymerase II contains a repetitive heptad sequence (YSPTSPS) whose phosphorylation states coordinate eukaryotic transcription by recruiting protein regulators. The precise placement and removal of phosphate groups on specific residues of the CTD are critical for the fidelity and effectiveness of RNA polymerase II-mediated transcription. During transcriptional elongation, phosphoryl-Ser5 (pSer5) is gradually dephosphorylated by CTD phosphatases, whereas Ser2 phosphorylation accumulates. Using MS, X-ray crystallography, protein engineering, and immunoblotting analyses, here we investigated the structure and function of SSU72 homolog, RNA polymerase II CTD phosphatase (Ssu72, from Drosophila melanogaster), an essential CTD phosphatase that dephosphorylates pSer5 at the transition from elongation to termination, to determine the mechanism by which Ssu72 distinguishes the highly similar pSer2 and pSer5 CTDs. We found that Ssu72 dephosphorylates pSer5 effectively but only has low activities toward pSer7 and pSer2 The structural analysis revealed that Ssu72 requires that the proline residue in the substrate's SP motif is in the cis configuration, forming a tight β-turn for recognition by Ssu72. We also noted that residues flanking the SP motif, such as the bulky Tyr1 next to Ser2, prevent the formation of such configuration and enable Ssu72 to distinguish among the different SP motifs. The phosphorylation of Tyr1 further prohibited Ssu72 binding to pSer2 and thereby prevented untimely Ser2 dephosphorylation. Our results reveal critical roles for Tyr1 in differentiating the phosphorylation states of Ser2/Ser5 of CTD in RNA polymerase II that occur at different stages of transcription.
Collapse
Affiliation(s)
- Seema Irani
- Department of Chemical Engineering, The University of Texas, Austin, Texas 78712; Department of Molecular Biosciences, The University of Texas, Austin, Texas 78712
| | - Sarah N Sipe
- Department of Chemistry, The University of Texas, Austin, Texas 78712
| | - Wanjie Yang
- Department of Molecular Biosciences, The University of Texas, Austin, Texas 78712
| | | | - Brian Lin
- Department of Molecular Biosciences, The University of Texas, Austin, Texas 78712
| | - Kelly Sim
- Department of Molecular Biosciences, The University of Texas, Austin, Texas 78712
| | - Wendy L Matthews
- Department of Molecular Biosciences, The University of Texas, Austin, Texas 78712
| | | | - Yan Zhang
- Department of Molecular Biosciences, The University of Texas, Austin, Texas 78712; Institute for Cellular and Molecular Biology, The University of Texas, Austin, Texas 78712.
| |
Collapse
|
6
|
Burriss KH, Mosley AL. Methods review: Mass spectrometry analysis of RNAPII complexes. Methods 2019; 159-160:105-114. [PMID: 30902665 DOI: 10.1016/j.ymeth.2019.03.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/04/2019] [Accepted: 03/17/2019] [Indexed: 12/20/2022] Open
Abstract
RNA Polymerase II (RNAPII) is responsible for transcribing multiple RNA species throughout eukaryotes. A variety of protein-protein interactions occur throughout the transcription cycle for coordinated regulation of transcription initiation, elongation, and/or termination. Taking a proteomics approach to study RNAPII transcription thereby offers a comprehensive view of both RNAPII biology and the variety of proteins that regulate the process itself. This review will focus on how mass spectrometry (MS) methods have expanded understanding of RNAPII and its transcription-regulatory interaction partners. The application of affinity purification mass spectrometry has led to the discovery of a number of novel groups of proteins that regulate an array of RNAPII biology ranging from nuclear import to regulation of phosphorylation state. Additionally, a number of methods have been developed using mass spectrometry to measure protein subunit stoichiometry within and across protein complexes and to perform various types of architectural analysis using structural proteomics approaches. The key methods that we will focus on related to RNAPII mass spectrometry analyses include: affinity purification mass spectrometry, protein post-translational modification analysis, crosslinking mass spectrometry, and native mass spectrometry.
Collapse
Affiliation(s)
- Katlyn Hughes Burriss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46402, United States
| | - Amber L Mosley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46402, United States; Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN 46402, United States.
| |
Collapse
|
7
|
Greer SM, Sidoli S, Coradin M, Schack Jespersen M, Schwämmle V, Jensen ON, Garcia BA, Brodbelt JS. Extensive Characterization of Heavily Modified Histone Tails by 193 nm Ultraviolet Photodissociation Mass Spectrometry via a Middle-Down Strategy. Anal Chem 2018; 90:10425-10433. [PMID: 30063333 PMCID: PMC6383154 DOI: 10.1021/acs.analchem.8b02320] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The ability to map combinatorial patterns of post-translational modifications (PTMs) of proteins remains challenging for traditional bottom-up mass spectrometry workflows. There are also hurdles associated with top-down approaches related to limited data analysis options for heavily modified proteoforms. These shortcomings have accelerated interest in middle-down MS methods that focus on analysis of large peptides generated by specific proteases in conjunction with validated bioinformatics strategies to allow quantification of isomeric histoforms. Mapping multiple PTMs simultaneously requires the ability to obtain high sequence coverage to allow confident localization of the modifications, and 193 nm ultraviolet photodissociation (UVPD) has been shown to cause extensive fragmentation for large peptides and proteins. Histones are an ideal system to test the ability of UVPD to characterize multiple modifications, as the combinations of PTMs are the underpinning of the biological significance of histones and at the same time create an imposing challenge for characterization. The present study focuses on applying 193 nm UVPD to the identification and localization of PTMs on histones by UVPD and comparison to a popular alternative, electron-transfer dissociation (ETD), via a high-throughput middle-down LC/MS/MS strategy. Histone Coder and IsoScale, bioinformatics tools for verification of PTM assignments and quantification of histone peptides, were adapted for UVPD data and applied in the present study. In total, over 300 modified forms were identified, and the distributions of PTMs were quantified between UVPD and ETD. Significant differences in patterns of PTMs were found for histones from HeLa cells prior to and after treatment with a deacetylase inhibitor. Additional fragment ion types generated by UVPD proved essential for extensive characterization of the most heavily modified forms (>5 PTMs).
Collapse
Affiliation(s)
- Sylvester M Greer
- Department of Chemistry , University of Texas at Austin , Austin , Texas 78712 , United States
| | - Simone Sidoli
- Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
| | - Mariel Coradin
- Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
| | - Malena Schack Jespersen
- Department of Biochemistry and Molecular Biology , University of Southern Denmark , DK-5230 Odense , Denmark
| | - Veit Schwämmle
- Department of Biochemistry and Molecular Biology , University of Southern Denmark , DK-5230 Odense , Denmark
| | - Ole N Jensen
- Department of Biochemistry and Molecular Biology , University of Southern Denmark , DK-5230 Odense , Denmark
| | - Benjamin A Garcia
- Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
| | - Jennifer S Brodbelt
- Department of Chemistry , University of Texas at Austin , Austin , Texas 78712 , United States
| |
Collapse
|
8
|
Burkholder NT, Medellin B, Irani S, Matthews W, Showalter SA, Zhang YJ. Chemical Tools for Studying the Impact of cis/trans Prolyl Isomerization on Signaling: A Case Study on RNA Polymerase II Phosphatase Activity and Specificity. Methods Enzymol 2018; 607:269-297. [PMID: 30149861 PMCID: PMC6701646 DOI: 10.1016/bs.mie.2018.04.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
Proline isomerization is ubiquitous in proteins and is important for regulating important processes such as folding, recognition, and enzymatic activity. In humans, peptidyl-prolyl isomerase cis-trans isomerase NIMA interacting 1 (Pin1) is responsible for mediating fast conversion between cis- and trans-conformations of serine/threonine-proline (S/T-P) motifs in a large number of cellular pathways, many of which are involved in normal development as well as progression of several cancers and diseases. One of the major processes that Pin1 regulates is phosphatase activity against the RNA polymerase II C-terminal domain (RNAPII CTD). However, molecular tools capable of distinguishing the effects of proline conformation on phosphatase function have been lacking. A key tool that allows us to understand isomeric specificity of proteins toward their substrates is the usage of proline mimicking isosteres that are locked to prevent cis/trans-proline conversion. These locked isosteres can be incorporated into standard peptide synthesis and then used in replacement of native substrates in various experimental techniques such as kinetic and thermodynamic assays as well as X-ray crystallography. We will describe the application of these chemical tools in detail using CTD phosphatases as an example. We will also discuss alternative methods for analyzing the effect of proline conformation such as 13C NMR and the biological implications of proline isomeric specificity of proteins. The chemical and analytical tools presented in this chapter are widely applicable and should help elucidate many questions on the role of proline isomerization in biology.
Collapse
Affiliation(s)
| | - Brenda Medellin
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, United States
| | - Seema Irani
- Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, United States
| | - Wendy Matthews
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, United States
| | - Scott A Showalter
- Department of Chemistry, Pennsylvania State University, University Park, PA, United States; Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, United States
| | - Yan Jessie Zhang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, United States; Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, United States.
| |
Collapse
|
9
|
Gibbs EB, Lu F, Portz B, Fisher MJ, Medellin BP, Laremore TN, Zhang YJ, Gilmour DS, Showalter SA. Phosphorylation induces sequence-specific conformational switches in the RNA polymerase II C-terminal domain. Nat Commun 2017; 8:15233. [PMID: 28497798 PMCID: PMC5437310 DOI: 10.1038/ncomms15233] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 03/09/2017] [Indexed: 01/25/2023] Open
Abstract
The carboxy-terminal domain (CTD) of the RNA polymerase II (Pol II) large subunit cycles through phosphorylation states that correlate with progression through the transcription cycle and regulate nascent mRNA processing. Structural analyses of yeast and mammalian CTD are hampered by their repetitive sequences. Here we identify a region of the Drosophila melanogaster CTD that is essential for Pol II function in vivo and capitalize on natural sequence variations within it to facilitate structural analysis. Mass spectrometry and NMR spectroscopy reveal that hyper-Ser5 phosphorylation transforms the local structure of this region via proline isomerization. The sequence context of this switch tunes the activity of the phosphatase Ssu72, leading to the preferential de-phosphorylation of specific heptads. Together, context-dependent conformational switches and biased dephosphorylation suggest a mechanism for the selective recruitment of cis-proline-specific regulatory factors and region-specific modulation of the CTD code that may augment gene regulation in developmentally complex organisms.
Collapse
Affiliation(s)
- Eric B Gibbs
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Feiyue Lu
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.,Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Bede Portz
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Michael J Fisher
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Brenda P Medellin
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712, USA
| | - Tatiana N Laremore
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Yan Jessie Zhang
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712, USA
| | - David S Gilmour
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Scott A Showalter
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.,Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| |
Collapse
|
10
|
Different phosphoisoforms of RNA polymerase II engage the Rtt103 termination factor in a structurally analogous manner. Proc Natl Acad Sci U S A 2017; 114:E3944-E3953. [PMID: 28465432 DOI: 10.1073/pnas.1700128114] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The carboxyl-terminal domain (CTD) of the largest subunit of RNA polymerase II (Pol II) orchestrates dynamic recruitment of specific cellular machines during different stages of transcription. Signature phosphorylation patterns of Y1S2P3T4S5P6S7 heptapeptide repeats of the CTD engage specific "readers." Whereas phospho-Ser5 and phospho-Ser2 marks are ubiquitous, phospho-Thr4 is reported to only impact specific genes. Here, we identify a role for phospho-Thr4 in transcription termination at noncoding small nucleolar RNA (snoRNA) genes. Quantitative proteomics reveals an interactome of known readers as well as protein complexes that were not known to rely on Thr4 for association with Pol II. The data indicate a key role for Thr4 in engaging the machinery used for transcription elongation and termination. We focus on Rtt103, a protein that binds phospho-Ser2 and phospho-Thr4 marks and facilitates transcription termination at protein-coding genes. To elucidate how Rtt103 engages two distinct CTD modifications that are differentially enriched at noncoding genes, we relied on NMR analysis of Rtt103 in complex with phospho-Thr4- or phospho-Ser2-bearing CTD peptides. The structural data reveal that Rtt103 interacts with phospho-Thr4 in a manner analogous to its interaction with phospho-Ser2-modified CTD. The same set of hydrogen bonds involving either the oxygen on phospho-Thr4 and the hydroxyl on Ser2, or the phosphate on Ser2 and the Thr4 hydroxyl, can be formed by rotation of an arginine side chain, leaving the intermolecular interface otherwise unperturbed. This economy of design enables Rtt103 to engage Pol II at distinct sets of genes with differentially enriched CTD marks.
Collapse
|
11
|
Mayfield JE, Robinson MR, Cotham VC, Irani S, Matthews WL, Ram A, Gilmour DS, Cannon JR, Zhang YJ, Brodbelt JS. Mapping the Phosphorylation Pattern of Drosophila melanogaster RNA Polymerase II Carboxyl-Terminal Domain Using Ultraviolet Photodissociation Mass Spectrometry. ACS Chem Biol 2017; 12:153-162. [PMID: 28103682 DOI: 10.1021/acschembio.6b00729] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Phosphorylation of the C-terminal domain of RNA polymerase II (CTD) plays an essential role in eukaryotic transcription by recruiting transcriptional regulatory factors to the active polymerase. However, the scarcity of basic residues and repetitive nature of the CTD sequence impose a huge challenge for site-specific characterization of phosphorylation, hindering our understanding of this crucial biological process. Herein, we apply LC-UVPD-MS methods to analyze post-translational modification along native sequence CTDs. Application of our method to the Drosophila melanogaster CTD reveals the phosphorylation pattern of this model organism for the first time. The divergent nature of fly CTD allows us to derive rules defining how flanking residues affect phosphorylation choice by CTD kinases. Our data support the use of LC-UVPD-MS to decipher the CTD code and determine rules that program its function.
Collapse
Affiliation(s)
| | | | | | | | | | | | - David S. Gilmour
- Department
of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania 16802, United States
| | | | | | | |
Collapse
|
12
|
Robinson MR, Taliaferro JM, Dalby KN, Brodbelt JS. 193 nm Ultraviolet Photodissociation Mass Spectrometry for Phosphopeptide Characterization in the Positive and Negative Ion Modes. J Proteome Res 2016; 15:2739-48. [PMID: 27425180 DOI: 10.1021/acs.jproteome.6b00289] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Advances in liquid chromatography tandem mass spectrometry (LC-MS/MS) have permitted phosphoproteomic analysis on a grand scale, but ongoing challenges specifically associated with confident phosphate localization continue to motivate the development of new fragmentation techniques. In the present study, ultraviolet photodissociation (UVPD) at 193 nm is evaluated for the characterization of phosphopeptides in both positive and negative ion modes. Compared to the more standard higher energy collisional dissociation (HCD), UVPD provided more extensive fragmentation with improved phosphate retention on product ions. Negative mode UVPD showed particular merit for detecting and sequencing highly acidic phosphopeptides from alpha and beta casein, but was not as robust for larger scale analysis because of lower ionization efficiencies in the negative mode. HeLa and HCC70 cell lysates were analyzed by both UVPD and HCD. While HCD identified more phosphopeptides and proteins compared to UVPD, the unique matches from UVPD analysis could be combined with the HCD data set to improve the overall depth of coverage compared to either method alone.
Collapse
Affiliation(s)
- Michelle R Robinson
- Department of Chemistry, and ‡Division of Chemical Biology and Medicinal Chemistry College of Pharmacy, The University of Texas Austin, Texas 78712, United States
| | - Juliana M Taliaferro
- Department of Chemistry, and ‡Division of Chemical Biology and Medicinal Chemistry College of Pharmacy, The University of Texas Austin, Texas 78712, United States
| | - Kevin N Dalby
- Department of Chemistry, and ‡Division of Chemical Biology and Medicinal Chemistry College of Pharmacy, The University of Texas Austin, Texas 78712, United States
| | - Jennifer S Brodbelt
- Department of Chemistry, and ‡Division of Chemical Biology and Medicinal Chemistry College of Pharmacy, The University of Texas Austin, Texas 78712, United States
| |
Collapse
|
13
|
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.
Collapse
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.
| |
Collapse
|
14
|
Affiliation(s)
- Jennifer S Brodbelt
- Department of Chemistry, University of Texas at Austin , Austin, Texas 78712, United States
| |
Collapse
|
15
|
Mayfield JE, Fan S, Wei S, Zhang M, Li B, Ellington AD, Etzkorn FA, Zhang YJ. Chemical Tools To Decipher Regulation of Phosphatases by Proline Isomerization on Eukaryotic RNA Polymerase II. ACS Chem Biol 2015; 10:2405-14. [PMID: 26332362 DOI: 10.1021/acschembio.5b00296] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Proline isomerization greatly impacts biological signaling but is subtle and difficult to detect in proteins. We characterize this poorly understood regulatory mechanism for RNA polymerase II carboxyl terminal domain (CTD) phosphorylation state using novel, direct, and quantitative chemical tools. We determine the proline isomeric preference of three CTD phosphatases: Ssu72 as cis-proline specific, Scp1 and Fcp1 as strongly trans-preferred. Due to this inherent characteristic, these phosphatases respond differently to enzymes that catalyze the isomerization of proline, like Ess1/Pin1. We demonstrate that this selective regulation of RNA polymerase II phosphorylation state exists within human cells, consistent with in vitro assays. These results support a model in which, instead of a global enhancement of downstream enzymatic activities, proline isomerases selectively boost the activity of a subset of CTD regulatory factors specific for cis-proline. This leads to diversified phosphorylation states of CTD in vitro and in cells. We provide the chemical tools to investigate proline isomerization and its ability to selectively enhance signaling in transcription and other biological contexts.
Collapse
Affiliation(s)
- Joshua E. Mayfield
- Department
of Molecular Biosciences and Institute for Cellular and Molecular
Biology, University of Texas at Austin, Austin, Texas 78712, United States
| | - Shuang Fan
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Shuo Wei
- 1 Cancer
Research Institute, Beth Israel Deaconess Cancer Center, Harvard Medical School, Boston, Massachusetts 02215, United States
- Department
of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, United States
| | - Mengmeng Zhang
- Department
of Molecular Biosciences and Institute for Cellular and Molecular
Biology, University of Texas at Austin, Austin, Texas 78712, United States
| | - Bing Li
- Department
of Molecular Biology, UT Southwestern Medical Center, 5323 Harry Hines
Boulevard, Dallas, Texas 75390, United States
| | - Andrew D. Ellington
- Department
of Molecular Biosciences and Institute for Cellular and Molecular
Biology, University of Texas at Austin, Austin, Texas 78712, United States
| | - Felicia A. Etzkorn
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Yan Jessie Zhang
- Department
of Molecular Biosciences and Institute for Cellular and Molecular
Biology, University of Texas at Austin, Austin, Texas 78712, United States
| |
Collapse
|
16
|
Zhang S, Shi Y, Wang W, Yuan Z. Study on the association between CTD peptides and zinc(ii)-dipicolylamine appended beta-cyclodextrin. RSC Adv 2015. [DOI: 10.1039/c5ra12374g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Association between zinc(ii)-dipicolylamine appended beta-cyclodextrin and CTD (carboxy-terminal domain of RNA polymerase II) peptides with different phosphorylation patterns was studied by ITC and NMR.
Collapse
Affiliation(s)
- Saihui Zhang
- Key Laboratory of Functional Polymer Materials of Ministry of Education
- Institute of Polymer Chemistry
- Nankai University and Collaborative Innovation Center of Chemical Science and Engineering
- Nankai University
- Tianjin 300071
| | - Yantao Shi
- Key Laboratory of Functional Polymer Materials of Ministry of Education
- Institute of Polymer Chemistry
- Nankai University and Collaborative Innovation Center of Chemical Science and Engineering
- Nankai University
- Tianjin 300071
| | - Wei Wang
- Key Laboratory of Functional Polymer Materials of Ministry of Education
- Institute of Polymer Chemistry
- Nankai University and Collaborative Innovation Center of Chemical Science and Engineering
- Nankai University
- Tianjin 300071
| | - Zhi Yuan
- Key Laboratory of Functional Polymer Materials of Ministry of Education
- Institute of Polymer Chemistry
- Nankai University and Collaborative Innovation Center of Chemical Science and Engineering
- Nankai University
- Tianjin 300071
| |
Collapse
|
17
|
Greer S, Cannon JR, Brodbelt JS. Improvement of shotgun proteomics in the negative mode by carbamylation of peptides and ultraviolet photodissociation mass spectrometry. Anal Chem 2014; 86:12285-90. [PMID: 25420043 PMCID: PMC4270407 DOI: 10.1021/ac5035314] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Accepted: 11/24/2014] [Indexed: 02/08/2023]
Abstract
Although acidic peptides compose a substantial portion of many proteomes, their less efficient ionization during positive polarity electrospray ionization (ESI) impedes their detection in bottom-up mass spectrometry workflows. We have implemented a derivatization strategy based on carbamylation which converts basic amine sites (Lys, N-termini) to less basic amides for enhanced analysis in the negative mode. Ultraviolet photodissociation (UVPD) is used to analyze the resulting peptide anions, as demonstrated for tryptic peptides from bovine serum albumin and Halobacterium salinarum in a high throughput liquid chromatography/tandem mass spectrometry (LC/MS/MS) mode. LC/UVPD-MS of a carbamylated H. salinarum digest resulted in 45% more identified peptides and 25% more proteins compared to the unmodified digest analyzed in the negative mode.
Collapse
Affiliation(s)
- Sylvester
M. Greer
- Department of Chemistry, University of
Texas at Austin, Austin, Texas 78712, United
States
| | - Joe R. Cannon
- Department of Chemistry, University of
Texas at Austin, Austin, Texas 78712, United
States
| | - Jennifer S. Brodbelt
- Department of Chemistry, University of
Texas at Austin, Austin, Texas 78712, United
States
| |
Collapse
|
18
|
Wani S, Yuda M, Fujiwara Y, Yamamoto M, Harada F, Ohkuma Y, Hirose Y. Vertebrate Ssu72 regulates and coordinates 3'-end formation of RNAs transcribed by RNA polymerase II. PLoS One 2014; 9:e106040. [PMID: 25166011 PMCID: PMC4148344 DOI: 10.1371/journal.pone.0106040] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 07/26/2014] [Indexed: 01/18/2023] Open
Abstract
In eukaryotes, the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II (Pol II) is composed of tandem repeats of the heptapeptide YSPTSPS, which is subjected to reversible phosphorylation at Ser2, Ser5, and Ser7 during the transcription cycle. Dynamic changes in CTD phosphorylation patterns, established by the activities of multiple kinases and phosphatases, are responsible for stage-specific recruitment of various factors involved in RNA processing, histone modification, and transcription elongation/termination. Yeast Ssu72, a CTD phosphatase specific for Ser5 and Ser7, functions in 3′-end processing of pre-mRNAs and in transcription termination of small non-coding RNAs such as snoRNAs and snRNAs. Vertebrate Ssu72 exhibits Ser5- and Ser7-specific CTD phosphatase activity in vitro, but its roles in gene expression and CTD dephosphorylation in vivo remain to be elucidated. To investigate the functions of vertebrate Ssu72 in gene expression, we established chicken DT40 B-cell lines in which Ssu72 expression was conditionally inactivated. Ssu72 depletion in DT40 cells caused defects in 3′-end formation of U2 and U4 snRNAs and GAPDH mRNA. Surprisingly, however, Ssu72 inactivation increased the efficiency of 3′-end formation of non-polyadenylated replication-dependent histone mRNA. Chromatin immunoprecipitation analyses revealed that Ssu72 depletion caused a significant increase in both Ser5 and Ser7 phosphorylation of the Pol II CTD on all genes in which 3′-end formation was affected. These results suggest that vertebrate Ssu72 plays positive roles in 3′-end formation of snRNAs and polyadenylated mRNAs, but negative roles in 3′-end formation of histone mRNAs, through dephosphorylation of both Ser5 and Ser7 of the CTD.
Collapse
Affiliation(s)
- Shotaro Wani
- Laboratory of Gene Regulation, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani, Toyama, Japan
| | - Masamichi Yuda
- Department of Molecular and Cellular Biology, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Japan
| | - Yosuke Fujiwara
- Laboratory of Gene Regulation, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani, Toyama, Japan
| | - Masaya Yamamoto
- Laboratory of Gene Regulation, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani, Toyama, Japan
| | - Fumio Harada
- Department of Molecular and Cellular Biology, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Japan
| | - Yoshiaki Ohkuma
- Laboratory of Gene Regulation, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani, Toyama, Japan
| | - Yutaka Hirose
- Laboratory of Gene Regulation, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani, Toyama, Japan
- * E-mail:
| |
Collapse
|
19
|
Brodbelt JS. Photodissociation mass spectrometry: new tools for characterization of biological molecules. Chem Soc Rev 2014; 43:2757-83. [PMID: 24481009 PMCID: PMC3966968 DOI: 10.1039/c3cs60444f] [Citation(s) in RCA: 232] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Photodissociation mass spectrometry combines the ability to activate and fragment ions using photons with the sensitive detection of the resulting product ions by mass spectrometry. This combination affords a versatile tool for characterization of biological molecules. The scope and breadth of photodissociation mass spectrometry have increased substantially over the past decade as new research groups have entered the field and developed a number of innovative applications that illustrate the ability of photodissociation to produce rich fragmentation patterns, to cleave bonds selectively, and to target specific molecules based on incorporation of chromophores. This review focuses on many of the key developments in photodissociation mass spectrometry over the past decade with a particular emphasis on its applications to biological molecules.
Collapse
|
20
|
Jurado AR, Tan D, Jiao X, Kiledjian M, Tong L. Structure and function of pre-mRNA 5'-end capping quality control and 3'-end processing. Biochemistry 2014; 53:1882-98. [PMID: 24617759 PMCID: PMC3977584 DOI: 10.1021/bi401715v] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Messenger RNA precursors (pre-mRNAs)
are produced as the nascent
transcripts of RNA polymerase II (Pol II) in eukaryotes and must undergo
extensive maturational processing, including 5′-end capping,
splicing, and 3′-end cleavage and polyadenylation. This review
will summarize the structural and functional information reported
over the past few years on the large machinery required for the 3′-end
processing of most pre-mRNAs, as well as the distinct machinery for
the 3′-end processing of replication-dependent histone pre-mRNAs,
which have provided great insights into the proteins and their subcomplexes
in these machineries. Structural and biochemical studies have also
led to the identification of a new class of enzymes (the DXO family
enzymes) with activity toward intermediates of the 5′-end capping
pathway. Functional studies demonstrate that these enzymes are part
of a novel quality surveillance mechanism for pre-mRNA 5′-end
capping. Incompletely capped pre-mRNAs are produced in yeast and human
cells, in contrast to the general belief in the field that capping
always proceeds to completion, and incomplete capping leads to defects
in splicing and 3′-end cleavage in human cells. The DXO family
enzymes are required for the detection and degradation of these defective
RNAs.
Collapse
Affiliation(s)
- Ashley R Jurado
- Department of Biological Sciences, Columbia University , New York, New York 10027, United States
| | | | | | | | | |
Collapse
|
21
|
Delineating the structural blueprint of the pre-mRNA 3'-end processing machinery. Mol Cell Biol 2014; 34:1894-910. [PMID: 24591651 DOI: 10.1128/mcb.00084-14] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Processing of mRNA precursors (pre-mRNAs) by polyadenylation is an essential step in gene expression. Polyadenylation consists of two steps, cleavage and poly(A) synthesis, and requires multiple cis elements in the pre-mRNA and a megadalton protein complex bearing the two essential enzymatic activities. While genetic and biochemical studies remain the major approaches in characterizing these factors, structural biology has emerged during the past decade to help understand the molecular assembly and mechanistic details of the process. With structural information about more proteins and higher-order complexes becoming available, we are coming closer to obtaining a structural blueprint of the polyadenylation machinery that explains both how this complex functions and how it is regulated and connected to other cellular processes.
Collapse
|
22
|
Liu WR. Reports from the Chemical Biology of Texas Symposium at the 69th Southwest Regional Meeting of the American Chemical Society. ACS Chem Biol 2014; 9:319-22. [PMID: 24556200 DOI: 10.1021/cb500046f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Wenshe R Liu
- Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States
| |
Collapse
|
23
|
Cannon JR, Cammarata M, Robotham SA, Cotham VC, Shaw JB, Fellers RT, Early BP, Thomas PM, Kelleher NL, Brodbelt JS. Ultraviolet photodissociation for characterization of whole proteins on a chromatographic time scale. Anal Chem 2014; 86:2185-92. [PMID: 24447299 PMCID: PMC3958131 DOI: 10.1021/ac403859a] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 01/21/2014] [Indexed: 02/01/2023]
Abstract
Intact protein characterization using mass spectrometry thus far has been achieved at the cost of throughput. Presented here is the application of 193 nm ultraviolet photodissociation (UVPD) for top down identification and characterization of proteins in complex mixtures in an online fashion. Liquid chromatographic separation at the intact protein level coupled with fast UVPD and high-resolution detection resulted in confident identification of 46 unique sequences compared to 44 using HCD from prepared Escherichia coli ribosomes. Importantly, nearly all proteins identified in both the UVPD and optimized HCD analyses demonstrated a substantial increase in confidence in identification (as defined by an average decrease in E value of ∼40 orders of magnitude) due to the higher number of matched fragment ions. Also shown is the potential for high-throughput characterization of intact proteins via liquid chromatography (LC)-UVPD-MS of molecular weight-based fractions of a Saccharomyces cerevisiae lysate. In total, protein products from 215 genes were identified and found in 292 distinct proteoforms, 168 of which contained some type of post-translational modification.
Collapse
Affiliation(s)
- Joe R. Cannon
- Department
of Chemistry, University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712, United States
| | - Michael
B. Cammarata
- Department
of Chemistry, University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712, United States
| | - Scott A. Robotham
- Department
of Chemistry, University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712, United States
| | - Victoria C. Cotham
- Department
of Chemistry, University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712, United States
| | - Jared B. Shaw
- Department
of Chemistry, University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712, United States
| | - Ryan T. Fellers
- Departments
of Chemistry and Molecular Biosciences and the Proteomics Center of
Excellence, Northwestern University, Evanston, Illinois 60208, United States
| | - Bryan P. Early
- Departments
of Chemistry and Molecular Biosciences and the Proteomics Center of
Excellence, Northwestern University, Evanston, Illinois 60208, United States
| | - Paul M. Thomas
- Departments
of Chemistry and Molecular Biosciences and the Proteomics Center of
Excellence, Northwestern University, Evanston, Illinois 60208, United States
| | - Neil L. Kelleher
- Departments
of Chemistry and Molecular Biosciences and the Proteomics Center of
Excellence, Northwestern University, Evanston, Illinois 60208, United States
| | - Jennifer S. Brodbelt
- Department
of Chemistry, University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712, United States
| |
Collapse
|
24
|
The Ess1 prolyl isomerase: traffic cop of the RNA polymerase II transcription cycle. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:316-33. [PMID: 24530645 DOI: 10.1016/j.bbagrm.2014.02.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Revised: 02/01/2014] [Accepted: 02/03/2014] [Indexed: 11/23/2022]
Abstract
Ess1 is a prolyl isomerase that regulates the structure and function of eukaryotic RNA polymerase II. Ess1 works by catalyzing the cis/trans conversion of pSer5-Pro6 bonds, and to a lesser extent pSer2-Pro3 bonds, within the carboxy-terminal domain (CTD) of Rpb1, the largest subunit of RNA pol II. Ess1 is conserved in organisms ranging from yeast to humans. In budding yeast, Ess1 is essential for growth and is required for efficient transcription initiation and termination, RNA processing, and suppression of cryptic transcription. In mammals, Ess1 (called Pin1) functions in a variety of pathways, including transcription, but it is not essential. Recent work has shown that Ess1 coordinates the binding and release of CTD-binding proteins that function as co-factors in the RNA pol II complex. In this way, Ess1 plays an integral role in writing (and reading) the so-called CTD code to promote production of mature RNA pol II transcripts including non-coding RNAs and mRNAs.
Collapse
|
25
|
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.
Collapse
|