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Sarsam RD, Xu J, Lahiri I, Gong W, Li Q, Oh J, Zhou Z, Hou P, Chong J, Hao N, Li S, Wang D, Leschziner AE. Elf1 promotes Rad26's interaction with lesion-arrested Pol II for transcription-coupled repair. Proc Natl Acad Sci U S A 2024; 121:e2314245121. [PMID: 38194460 PMCID: PMC10801861 DOI: 10.1073/pnas.2314245121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 11/27/2023] [Indexed: 01/11/2024] Open
Abstract
Transcription-coupled nucleotide excision repair (TC-NER) is a highly conserved DNA repair pathway that removes bulky lesions in the transcribed genome. Cockayne syndrome B protein (CSB), or its yeast ortholog Rad26, has been known for decades to play important roles in the lesion-recognition steps of TC-NER. Another conserved protein ELOF1, or its yeast ortholog Elf1, was recently identified as a core transcription-coupled repair factor. How Rad26 distinguishes between RNA polymerase II (Pol II) stalled at a DNA lesion or other obstacles and what role Elf1 plays in this process remains unknown. Here, we present cryo-EM structures of Pol II-Rad26 complexes stalled at different obstacles that show that Rad26 uses a common mechanism to recognize a stalled Pol II, with additional interactions when Pol II is arrested at a lesion. A cryo-EM structure of lesion-arrested Pol II-Rad26 bound to Elf1 revealed that Elf1 induces further interactions between Rad26 and a lesion-arrested Pol II. Biochemical and genetic data support the importance of the interplay between Elf1 and Rad26 in TC-NER initiation. Together, our results provide important mechanistic insights into how two conserved transcription-coupled repair factors, Rad26/CSB and Elf1/ELOF1, work together at the initial lesion recognition steps of transcription-coupled repair.
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Affiliation(s)
- Reta D. Sarsam
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA92093
| | - Jun Xu
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA92093
| | - Indrajit Lahiri
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA92093
| | - Wenzhi Gong
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA70803
| | - Qingrong Li
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA92093
| | - Juntaek Oh
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA92093
| | - Zhen Zhou
- Department of Molecular Biology, School of Biological Sciences, University of California San Diego, La Jolla, CA92093
| | - Peini Hou
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA92093
| | - Jenny Chong
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA92093
| | - Nan Hao
- Department of Molecular Biology, School of Biological Sciences, University of California San Diego, La Jolla, CA92093
| | - Shisheng Li
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA70803
| | - Dong Wang
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA92093
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA92093
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA92093
| | - Andres E. Leschziner
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA92093
- Department of Molecular Biology, School of Biological Sciences, University of California San Diego, La Jolla, CA92093
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S Cannon K, Sarsam RD, Tedamrongwanish T, Zhang K, Baker RW. Lipid nanodiscs as a template for high-resolution cryo-EM structures of peripheral membrane proteins. J Struct Biol 2023; 215:107989. [PMID: 37364761 DOI: 10.1016/j.jsb.2023.107989] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/05/2023] [Accepted: 06/23/2023] [Indexed: 06/28/2023]
Abstract
Peripheral membrane proteins are ubiquitous throughout cell biology and are required for a variety of cellular processes such as signal transduction, membrane trafficking, and autophagy. Transient binding to the membrane has a profound impact on protein function, serving to induce conformational changes and alter biochemical and biophysical parameters by increasing the local concentration of factors and restricting diffusion to two dimensions. Despite the centrality of the membrane in serving as a template for cell biology, there are few reported high-resolution structures of peripheral membrane proteins bound to the membrane. We analyzed the utility of lipid nanodiscs to serve as a template for cryo-EM analysis of peripheral membrane proteins. We tested a variety of nanodiscs and we report a 3.3 Å structure of the AP2 clathrin adaptor complex bound to a 17-nm nanodisc, with sufficient resolution to visualize a bound lipid head group. Our data demonstrate that lipid nanodiscs are amenable to high-resolution structure determination of peripheral membrane proteins and provide a framework for extending this analysis to other systems.
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Affiliation(s)
- Kevin S Cannon
- Department of Biochemistry and Biophysics, UNC Chapel Hill School of Medicine, Chapel Hill, NC 27516, USA
| | - Reta D Sarsam
- Department of Biochemistry and Biophysics, UNC Chapel Hill School of Medicine, Chapel Hill, NC 27516, USA
| | - Tanita Tedamrongwanish
- Department of Biochemistry and Biophysics, UNC Chapel Hill School of Medicine, Chapel Hill, NC 27516, USA
| | - Kevin Zhang
- Department of Biochemistry and Biophysics, UNC Chapel Hill School of Medicine, Chapel Hill, NC 27516, USA
| | - Richard W Baker
- Department of Biochemistry and Biophysics, UNC Chapel Hill School of Medicine, Chapel Hill, NC 27516, USA; UNC Lineberger Comprehensive Cancer Center, UNC Chapel Hill School of Medicine, Chapel Hill, NC 27516, USA.
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Abstract
In many organisms, 3'-phosphoadenosine 5'-phosphate (PAP) is a product of two reactions in the sulfur activation pathway. The sulfurylation of biomolecules, catalyzed by sulfotransferases, uses 3'-phosphoadenosine 5'-phosphosulfate (PAPS) as a sulfate donor, producing the sulfated biomolecule and PAP product. Additionally, the first step in sulfate reduction for many bacteria and fungi reduces the sulfate moiety of PAPS, producing PAP and sulfite, which is subsequently reduced to sulfide. PAP is removed by the phosphatase activity of CysQ, a 3',5'-bisphosphate nucleotidase, yielding AMP and phosphate. Because excess PAP alters the equilibrium of the sulfur pathway and inhibits sulfotransferases, PAP concentrations can affect the levels of sulfur-containing metabolites. Therefore, CysQ, a divalent cation metal-dependent phosphatase, is a major regulator of this pathway. CysQ (Rv2131c) from Mycobacterium tuberculosis (Mtb) was successfully expressed, purified, and crystallized in a variety of ligand-bound states. Here we report six crystal structures of Mtb CysQ, including a ligand-free structure, a lithium-inhibited state with substrate PAP bound, and a product-bound complex with AMP, phosphate, and three Mg(2+) ions bound. Comparison of these structures together with homologues of the superfamily has provided insight into substrate specificity, metal coordination, and catalytic mechanism.
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Affiliation(s)
- Anna I Erickson
- Department of Chemistry, ‡Department of Molecular and Cellular Biology, and §Graduate Program in Biochemistry and Molecular, Cellular and Developmental Biology, University of California , One Shields Avenue, Davis, California 95616, United States
| | - Reta D Sarsam
- Department of Chemistry, ‡Department of Molecular and Cellular Biology, and §Graduate Program in Biochemistry and Molecular, Cellular and Developmental Biology, University of California , One Shields Avenue, Davis, California 95616, United States
| | - Andrew J Fisher
- Department of Chemistry, ‡Department of Molecular and Cellular Biology, and §Graduate Program in Biochemistry and Molecular, Cellular and Developmental Biology, University of California , One Shields Avenue, Davis, California 95616, United States
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Murley A, Sarsam RD, Toulmay A, Yamada J, Prinz WA, Nunnari J. Ltc1 is an ER-localized sterol transporter and a component of ER-mitochondria and ER-vacuole contacts. ACTA ACUST UNITED AC 2015; 209:539-48. [PMID: 25987606 PMCID: PMC4442815 DOI: 10.1083/jcb.201502033] [Citation(s) in RCA: 196] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 04/21/2015] [Indexed: 11/22/2022]
Abstract
Organelle contact sites perform fundamental functions in cells, including lipid and ion homeostasis, membrane dynamics, and signaling. Using a forward proteomics approach in yeast, we identified new ER-mitochondria and ER-vacuole contacts specified by an uncharacterized protein, Ylr072w. Ylr072w is a conserved protein with GRAM and VASt domains that selectively transports sterols and is thus termed Ltc1, for Lipid transfer at contact site 1. Ltc1 localized to ER-mitochondria and ER-vacuole contacts via the mitochondrial import receptors Tom70/71 and the vacuolar protein Vac8, respectively. At mitochondria, Ltc1 was required for cell viability in the absence of Mdm34, a subunit of the ER-mitochondria encounter structure. At vacuoles, Ltc1 was required for sterol-enriched membrane domain formation in response to stress. Increasing the proportion of Ltc1 at vacuoles was sufficient to induce sterol-enriched vacuolar domains without stress. Thus, our data support a model in which Ltc1 is a sterol-dependent regulator of organelle and cellular homeostasis via its dual localization to ER-mitochondria and ER-vacuole contact sites.
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Affiliation(s)
- Andrew Murley
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616
| | - Reta D Sarsam
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616
| | - Alexandre Toulmay
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Justin Yamada
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616
| | - William A Prinz
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Jodi Nunnari
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616
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Erickson AI, Sarsam RD, Fisher AJ. Expression, purification and preliminary crystallographic analysis of Mycobacterium tuberculosis CysQ, a phosphatase involved in sulfur metabolism. Acta Crystallogr F Struct Biol Commun 2014; 70:750-3. [PMID: 24915085 DOI: 10.1107/s2053230x14008619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 04/16/2014] [Indexed: 11/10/2022]
Abstract
CysQ is part of the sulfur-activation pathway that dephosphorylates 3'-phosphoadenosine 5'-monophosphate (PAP) to regenerate adenosine 5'-monophosphate (AMP) and free phosphate. PAP is the product of sulfate-transfer reactions from sulfotransferases that use the universal sulfate donor 3'-phosphoadenosine 5'-phosphosulfate (PAPS). In some organisms PAP is also the product of PAPS reductases that reduce sulfate from PAPS to sulfite. CysQ from Mycobacterium tuberculosis, which plays an important role in the biosynthesis of sulfated glycoconjugates, was successfully purified and crystallized in 24% PEG 1500, 20% glycerol. X-ray diffraction data were collected to 1.7 Å resolution using a synchrotron-radiation source. Crystals grew in the orthorhombic space group P2₁2₁2₁, with unit-cell parameters a=40.3, b=57.9, c=101.7 Å and with one monomer per asymmetric unit.
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Affiliation(s)
- Anna I Erickson
- Graduate Program in Biochemistry, Molecular, Cellular and Developmental Biology, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Reta D Sarsam
- Department of Molecular and Cellular Biology, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Andrew J Fisher
- Graduate Program in Biochemistry, Molecular, Cellular and Developmental Biology, University of California, One Shields Avenue, Davis, CA 95616, USA
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