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Vaccaro FA, Faber DA, Andree GA, Born DA, Kang G, Fonseca DR, Jost M, Drennan CL. Structural insight into G-protein chaperone-mediated maturation of a bacterial adenosylcobalamin-dependent mutase. J Biol Chem 2023; 299:105109. [PMID: 37517695 PMCID: PMC10481361 DOI: 10.1016/j.jbc.2023.105109] [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: 05/23/2023] [Revised: 07/20/2023] [Accepted: 07/25/2023] [Indexed: 08/01/2023] Open
Abstract
G-protein metallochaperones are essential for the proper maturation of numerous metalloenzymes. The G-protein chaperone MMAA in humans (MeaB in bacteria) uses GTP hydrolysis to facilitate the delivery of adenosylcobalamin (AdoCbl) to AdoCbl-dependent methylmalonyl-CoA mutase, an essential metabolic enzyme. This G-protein chaperone also facilitates the removal of damaged cobalamin (Cbl) for repair. Although most chaperones are standalone proteins, isobutyryl-CoA mutase fused (IcmF) has a G-protein domain covalently attached to its target mutase. We previously showed that dimeric MeaB undergoes a 180° rotation to reach a state capable of GTP hydrolysis (an active G-protein state), in which so-called switch III residues of one protomer contact the G-nucleotide of the other protomer. However, it was unclear whether other G-protein chaperones also adopted this conformation. Here, we show that the G-protein domain in a fused system forms a similar active conformation, requiring IcmF oligomerization. IcmF oligomerizes both upon Cbl damage and in the presence of the nonhydrolyzable GTP analog, guanosine-5'-[(β,γ)-methyleno]triphosphate, forming supramolecular complexes observable by mass photometry and EM. Cryo-EM structural analysis reveals that the second protomer of the G-protein intermolecular dimer props open the mutase active site using residues of switch III as a wedge, allowing for AdoCbl insertion or damaged Cbl removal. With the series of structural snapshots now available, we now describe here the molecular basis of G-protein-assisted AdoCbl-dependent mutase maturation, explaining how GTP binding prepares a mutase for cofactor delivery and how GTP hydrolysis allows the mutase to capture the cofactor.
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Affiliation(s)
- Francesca A Vaccaro
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Daphne A Faber
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Gisele A Andree
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - David A Born
- Graduate Program in Biophysics, Harvard University, Cambridge, Massachusetts, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Gyunghoon Kang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Dallas R Fonseca
- Amgen Scholar Program, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Marco Jost
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Catherine L Drennan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
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Mathur Y, Sreyas S, Datar PM, Sathian MB, Hazra AB. CobT and BzaC catalyze the regiospecific activation and methylation of the 5-hydroxybenzimidazole lower ligand in anaerobic cobamide biosynthesis. J Biol Chem 2020; 295:10522-10534. [PMID: 32503839 PMCID: PMC7397103 DOI: 10.1074/jbc.ra120.014197] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/01/2020] [Indexed: 11/06/2022] Open
Abstract
Vitamin B12 and other cobamides are essential cofactors required by many organisms and are synthesized by a subset of prokaryotes via distinct aerobic and anaerobic routes. The anaerobic biosynthesis of 5,6-dimethylbenzimidazole (DMB), the lower ligand of vitamin B12, involves five reactions catalyzed by the bza operon gene products, namely the hydroxybenzimidazole synthase BzaAB/BzaF, phosphoribosyltransferase CobT, and three methyltransferases, BzaC, BzaD, and BzaE, that conduct three distinct methylation steps. Of these, the methyltransferases that contribute to benzimidazole lower ligand diversity in cobamides remain to be characterized, and the precise role of the bza operon protein CobT is unclear. In this study, we used the bza operon from the anaerobic bacterium Moorella thermoacetica (comprising bzaA-bzaB-cobT-bzaC) to examine the role of CobT and investigate the activity of the first methyltransferase, BzaC. We studied the phosphoribosylation catalyzed by MtCobT and found that it regiospecifically activates 5-hydroxybenzimidazole (5-OHBza) to form the 5-OHBza-ribotide (5-OHBza-RP) isomer as the sole product. Next, we characterized the domains of MtBzaC and reconstituted its methyltransferase activity with the predicted substrate 5-OHBza and with two alternative substrates, the MtCobT product 5-OHBza-RP and its riboside derivative 5-OHBza-R. Unexpectedly, we found that 5-OHBza-R is the most favored MtBzaC substrate. Our results collectively explain the long-standing observation that the attachment of the lower ligand in anaerobic cobamide biosynthesis is regiospecific. In conclusion, we validate MtBzaC as a SAM:hydroxybenzimidazole-riboside methyltransferase (HBIR-OMT). Finally, we propose a new pathway for the synthesis and activation of the benzimidazolyl lower ligand in anaerobic cobamide biosynthesis.
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Affiliation(s)
- Yamini Mathur
- Department of Biology, Indian Institute of Science Education and Research, Pune, India
| | - Sheryl Sreyas
- Department of Chemistry, Indian Institute of Science Education and Research, Pune, India
| | - Prathamesh M Datar
- Department of Chemistry, Indian Institute of Science Education and Research, Pune, India
| | - Manjima B Sathian
- Department of Chemistry, Indian Institute of Science Education and Research, Pune, India
| | - Amrita B Hazra
- Department of Biology, Indian Institute of Science Education and Research, Pune, India
- Department of Chemistry, Indian Institute of Science Education and Research, Pune, India
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Mascarenhas R, Li Z, Gherasim C, Ruetz M, Banerjee R. The human B 12 trafficking protein CblC processes nitrocobalamin. J Biol Chem 2020; 295:9630-9640. [PMID: 32457044 DOI: 10.1074/jbc.ra120.014094] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/22/2020] [Indexed: 01/12/2023] Open
Abstract
In humans, cobalamin or vitamin B12 is delivered to two target enzymes via a complex intracellular trafficking pathway comprising transporters and chaperones. CblC (or MMACHC) is a processing chaperone that catalyzes an early step in this trafficking pathway. CblC removes the upper axial ligand of cobalamin derivatives, forming an intermediate in the pathway that is subsequently converted to the active cofactor derivatives. Mutations in the cblC gene lead to methylmalonic aciduria and homocystinuria. Here, we report that nitrosylcobalamin (NOCbl), which was developed as an antiproliferative reagent, and is purported to cause cell death by virtue of releasing nitric oxide, is highly unstable in air and is rapidly oxidized to nitrocobalamin (NO2Cbl). We demonstrate that CblC catalyzes the GSH-dependent denitration of NO2Cbl forming 5-coordinate cob(II)alamin, which had one of two fates. It could be oxidized to aquo-cob(III)alamin or enter a futile thiol oxidase cycle forming GSH disulfide. Arg-161 in the active site of CblC suppressed the NO2Cbl-dependent thiol oxidase activity, whereas the disease-associated R161G variant stabilized cob(II)alamin and promoted futile cycling. We also report that CblC exhibits nitrite reductase activity, converting cob(I)alamin and nitrite to NOCbl. Finally, the denitration activity of CblC supported cell proliferation in the presence of NO2Cbl, which can serve as a cobalamin source. The newly described nitrite reductase and denitration activities of CblC extend its catalytic versatility, adding to its known decyanation and dealkylation activities. In summary, upon exposure to air, NOCbl is rapidly converted to NO2Cbl, which is a substrate for the B12 trafficking enzyme CblC.
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Affiliation(s)
- Romila Mascarenhas
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan, USA
| | - Zhu Li
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan, USA
| | - Carmen Gherasim
- Department of Pathology, University of Michigan Medical Center, Ann Arbor, Michigan, USA
| | - Markus Ruetz
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan, USA
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan, USA
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Abstract
Modified tetrapyrroles are large macrocyclic compounds, consisting of diverse conjugation and metal chelation systems and imparting an array of colors to the biological structures that contain them. Tetrapyrroles represent some of the most complex small molecules synthesized by cells and are involved in many essential processes that are fundamental to life on Earth, including photosynthesis, respiration, and catalysis. These molecules are all derived from a common template through a series of enzyme-mediated transformations that alter the oxidation state of the macrocycle and also modify its size, its side-chain composition, and the nature of the centrally chelated metal ion. The different modified tetrapyrroles include chlorophylls, hemes, siroheme, corrins (including vitamin B12), coenzyme F430, heme d1, and bilins. After nearly a century of study, almost all of the more than 90 different enzymes that synthesize this family of compounds are now known, and expression of reconstructed operons in heterologous hosts has confirmed that most pathways are complete. Aside from the highly diverse nature of the chemical reactions catalyzed, an interesting aspect of comparative biochemistry is to see how different enzymes and even entire pathways have evolved to perform alternative chemical reactions to produce the same end products in the presence and absence of oxygen. Although there is still much to learn, our current understanding of tetrapyrrole biogenesis represents a remarkable biochemical milestone that is summarized in this review.
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Affiliation(s)
- Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Martin J Warren
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, United Kingdom
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, United Kingdom
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Kang L, Liu Y, Shen M, Liu Y, He R, Song J, Jin Y, Li M, Zhang Y, Dong H, Liu X, Yan H, Qin J, Zheng H, Chen Y, Li D, Wei H, Zhang H, Sun L, Zhu Z, Liang D, Yang Y. A study on a cohort of 301 Chinese patients with isolated methylmalonic acidemia. J Inherit Metab Dis 2020; 43:409-423. [PMID: 31622506 DOI: 10.1002/jimd.12183] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 09/28/2019] [Accepted: 10/16/2019] [Indexed: 01/03/2023]
Abstract
Methylmalonic acidemia (MMA) is the most common organic acidemia in China. This study aimed to characterise the genotypic and phenotypic variabilities, and the molecular epidemiology of Chinese patients with isolated MMA. Patients (n = 301) with isolated MMA were diagnosed by clinical examination, biochemical assays, and genetic analysis. Fifty-eight patients (19.3%) were detected by newborn screening and 243 patients (80.7%) were clinically diagnosed after onset. Clinical onset ranged from the age of 3 days to 23 years (mean age = 1.01 ± 0.15 years). Among 234 MMA patients whose detailed clinical data were available, 170 (72.6%) had early onset disease (before the age of 1 year), and 64 (27.4%) had late-onset disease. The 234 MMA patients manifested with neuropsychiatric impairment (65.4%), haematological abnormality (31.6%), renal damage (8.5%), and metabolic crises (67.1%). Haematological abnormality was significantly more common in early-onset patients than that in late-onset patients. The incidence of metabolic crises was significantly high (P < 0.001) in patients with mut type than those with other types of isolated MMA. Variations (n = 122) were identified in MMUT, MMAA, MMAB, MMADHC, SUCLG1, and SUCLA2, of which 45 were novel. c.729_730insTT was the most frequent MMUT mutation, with a significantly higher frequency in our patients than that in 151 reported European patients. The frequency of c.914T>C in MMUT in our cohort was also higher than that in 151 European patients. MMUT mutations c.729_730insTT and c.914T>C are specific for the Chinese population. Our study expanded the spectrum of phenotypes and genotypes in isolated MMA.
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Affiliation(s)
- Lulu Kang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yupeng Liu
- Department of Pediatrics, People's Hospital of Peking University, Beijing, China
| | - Ming Shen
- Translational Medicine Laboratory, Chinese People's Liberation Army General Hospital, Beijing, China
| | - Yi Liu
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Ruxuan He
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Jinqing Song
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Ying Jin
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Mengqiu Li
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yao Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Hui Dong
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xueqin Liu
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Hui Yan
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Jiong Qin
- Department of Pediatrics, People's Hospital of Peking University, Beijing, China
| | - Hong Zheng
- Department of Pediatrics, First Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou, China
| | - Yongxing Chen
- Department of Endocrinology and Genetic, Henan Children's Hospital, Zhengzhou, China
| | - Dongxiao Li
- Department of Endocrinology and Genetic, Henan Children's Hospital, Zhengzhou, China
| | - Haiyan Wei
- Department of Endocrinology and Genetic, Henan Children's Hospital, Zhengzhou, China
| | - Huifeng Zhang
- Department of Pediatrics, Hebei Medical University Second Hospital, Shijiazhuang, China
| | - Liying Sun
- Center of Liver Transplantation, Beijing Friendship Hospital, Beijing, China
| | - Zhijun Zhu
- Center of Liver Transplantation, Beijing Friendship Hospital, Beijing, China
| | - Desheng Liang
- Center of Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Yanling Yang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
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6
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Banerjee R. Balancing on the road less traveled. J Biol Chem 2019; 294:6685-6688. [PMID: 30923127 DOI: 10.1074/jbc.aw119.008136] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sitting down to the task of writing, I found my pen drifting inexorably to a personal recollection of the metaphorical transcontinental road that I had traveled to become a scientist, instead of reviewing a facet of our scientific contributions. Factors that prepared me for my improbable journey in an era when international calls were operator-assisted and unaffordable and the internet was the stuff of science fiction were my family's love and the sheltered environment of my all-girls school and college experiences, which nurtured my self-confidence. The path of scientific inquiry is heady, and it is hard. The paucity of diversity, of women and minorities, particularly as the road steepens, helps perpetuate stereotypes and inadvertently encourages disparities. It is my hope that by sharing snippets of my journey, enriched as it has been by a diversity of mentors, mentees, colleagues, and friends, and the opportunity to express my curiosity and creativity, that a young person contemplating the scientific road will find encouragement.
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Affiliation(s)
- Ruma Banerjee
- From the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109
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7
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Fernández-Zapata J, Pérez-Castaño R, Aranda J, Colizzi F, Polanco MC, Orozco M, Padmanabhan S, Elías-Arnanz M. Plasticity in oligomerization, operator architecture, and DNA binding in the mode of action of a bacterial B 12-based photoreceptor. J Biol Chem 2018; 293:17888-17905. [PMID: 30262667 DOI: 10.1074/jbc.ra118.004838] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 09/20/2018] [Indexed: 11/06/2022] Open
Abstract
Newly discovered bacterial photoreceptors called CarH sense light by using 5'-deoxyadenosylcobalamin (AdoCbl). They repress their own expression and that of genes for carotenoid synthesis by binding in the dark to operator DNA as AdoCbl-bound tetramers, whose light-induced disassembly relieves repression. High-resolution structures of Thermus thermophilus CarHTt have provided snapshots of the dark and light states and have revealed a unique DNA-binding mode whereby only three of four DNA-binding domains contact an operator comprising three tandem direct repeats. To gain further insights into CarH photoreceptors and employing biochemical, spectroscopic, mutational, and computational analyses, here we investigated CarHBm from Bacillus megaterium We found that apoCarHBm, unlike monomeric apoCarHTt, is an oligomeric molten globule that forms DNA-binding tetramers in the dark only upon AdoCbl binding, which requires a conserved W-X 9-EH motif. Light relieved DNA binding by disrupting CarHBm tetramers to dimers, rather than to monomers as with CarHTt CarHBm operators resembled that of CarHTt, but were larger by one repeat and overlapped with the -35 or -10 promoter elements. This design persisted in a six-repeat, multipartite operator we discovered upstream of a gene encoding an Spx global redox-response regulator whose photoregulated expression links photooxidative and general redox responses in B. megaterium Interestingly, CarHBm recognized the smaller CarHTt operator, revealing an adaptability possibly related to the linker bridging the DNA- and AdoCbl-binding domains. Our findings highlight a remarkable plasticity in the mode of action of B12-based CarH photoreceptors, important for their biological functions and development as optogenetic tools.
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Affiliation(s)
- Jesús Fernández-Zapata
- From the Instituto de Química Física "Rocasolano," Consejo Superior de Investigaciones Científicas, 28006 Madrid
| | - Ricardo Pérez-Castaño
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al Instituto de Química Física "Rocasolano," Consejo Superior de Investigaciones Científicas), Facultad de Biología, Universidad de Murcia, Murcia 30100
| | - Juan Aranda
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona; Joint BSC-IRB Research Program in Computational Biology, Baldiri Reixac 10-12, 08028 Barcelona
| | - Francesco Colizzi
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona; Joint BSC-IRB Research Program in Computational Biology, Baldiri Reixac 10-12, 08028 Barcelona
| | - María Carmen Polanco
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al Instituto de Química Física "Rocasolano," Consejo Superior de Investigaciones Científicas), Facultad de Biología, Universidad de Murcia, Murcia 30100
| | - Modesto Orozco
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona; Joint BSC-IRB Research Program in Computational Biology, Baldiri Reixac 10-12, 08028 Barcelona; Department of Biochemistry and Biomedicine, University of Barcelona, 08028 Barcelona, Spain
| | - S Padmanabhan
- From the Instituto de Química Física "Rocasolano," Consejo Superior de Investigaciones Científicas, 28006 Madrid.
| | - Montserrat Elías-Arnanz
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al Instituto de Química Física "Rocasolano," Consejo Superior de Investigaciones Científicas), Facultad de Biología, Universidad de Murcia, Murcia 30100.
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8
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Campanello GC, Lofgren M, Yokom AL, Southworth DR, Banerjee R. Switch I-dependent allosteric signaling in a G-protein chaperone-B 12 enzyme complex. J Biol Chem 2017; 292:17617-17625. [PMID: 28882898 DOI: 10.1074/jbc.m117.786095] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 08/14/2017] [Indexed: 11/06/2022] Open
Abstract
G-proteins regulate various processes ranging from DNA replication and protein synthesis to cytoskeletal dynamics and cofactor assimilation and serve as models for uncovering strategies deployed for allosteric signal transduction. MeaB is a multifunctional G-protein chaperone, which gates loading of the active 5'-deoxyadenosylcobalamin cofactor onto methylmalonyl-CoA mutase (MCM) and precludes loading of inactive cofactor forms. MeaB also safeguards MCM, which uses radical chemistry, against inactivation and rescues MCM inactivated during catalytic turnover by using the GTP-binding energy to offload inactive cofactor. The conserved switch I and II signaling motifs used by G-proteins are predicted to mediate allosteric regulation in response to nucleotide binding and hydrolysis in MeaB. Herein, we targeted conserved residues in the MeaB switch I motif to interrogate the function of this loop. Unexpectedly, the switch I mutations had only modest effects on GTP binding and on GTPase activity and did not perturb stability of the MCM-MeaB complex. However, these mutations disrupted multiple MeaB chaperone functions, including cofactor editing, loading, and offloading. Hence, although residues in the switch I motif are not essential for catalysis, they are important for allosteric regulation. Furthermore, single-particle EM analysis revealed, for the first time, the overall architecture of the MCM-MeaB complex, which exhibits a 2:1 stoichiometry. These EM studies also demonstrate that the complex exhibits considerable conformational flexibility. In conclusion, the switch I element does not significantly stabilize the MCM-MeaB complex or influence the affinity of MeaB for GTP but is required for transducing signals between MeaB and MCM.
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Affiliation(s)
- Gregory C Campanello
- From the Departments of Biological Chemistry, University of Michigan Medical Center, and
| | - Michael Lofgren
- From the Departments of Biological Chemistry, University of Michigan Medical Center, and
| | - Adam L Yokom
- From the Departments of Biological Chemistry, University of Michigan Medical Center, and.,the Department of Biological Chemistry and.,the Graduate Program in Chemical Biology, Life Sciences Institute, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600
| | - Daniel R Southworth
- From the Departments of Biological Chemistry, University of Michigan Medical Center, and.,the Department of Biological Chemistry and
| | - Ruma Banerjee
- From the Departments of Biological Chemistry, University of Michigan Medical Center, and
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Polaski JT, Webster SM, Johnson JE, Batey RT. Cobalamin riboswitches exhibit a broad range of ability to discriminate between methylcobalamin and adenosylcobalamin. J Biol Chem 2017; 292:11650-11658. [PMID: 28483920 DOI: 10.1074/jbc.m117.787176] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 05/04/2017] [Indexed: 12/15/2022] Open
Abstract
Riboswitches are a widely distributed class of regulatory RNAs in bacteria that modulate gene expression via small-molecule-induced conformational changes. Generally, these RNA elements are grouped into classes based upon conserved primary and secondary structure and their cognate effector molecule. Although this approach has been very successful in identifying new riboswitch families and defining their distributions, small sequence differences between structurally related RNAs can alter their ligand selectivity and regulatory behavior. Herein, we use a structure-based mutagenic approach to demonstrate that cobalamin riboswitches have a broad spectrum of preference for the two biological forms of cobalamin in vitro using isothermal titration calorimetry. This selectivity is primarily mediated by the interaction between a peripheral element of the RNA that forms a T-loop module and a subset of nucleotides in the cobalamin-binding pocket. Cell-based fluorescence reporter assays in Escherichia coli revealed that mutations that switch effector preference in vitro lead to differential regulatory responses in a biological context. These data demonstrate that a more comprehensive analysis of representative sequences of both previously and newly discovered classes of riboswitches might reveal subgroups of RNAs that respond to different effectors. Furthermore, this study demonstrates a second distinct means by which tertiary structural interactions in cobalamin riboswitches dictate ligand selectivity.
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Affiliation(s)
- Jacob T Polaski
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309
| | - Samantha M Webster
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309
| | - James E Johnson
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309
| | - Robert T Batey
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309.
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10
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Li Z, Shanmuganathan A, Ruetz M, Yamada K, Lesniak NA, Kräutler B, Brunold TC, Koutmos M, Banerjee R. Coordination chemistry controls the thiol oxidase activity of the B 12-trafficking protein CblC. J Biol Chem 2017; 292:9733-9744. [PMID: 28442570 DOI: 10.1074/jbc.m117.788554] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 04/20/2017] [Indexed: 01/20/2023] Open
Abstract
The cobalamin or B12 cofactor supports sulfur and one-carbon metabolism and the catabolism of odd-chain fatty acids, branched-chain amino acids, and cholesterol. CblC is a B12-processing enzyme involved in an early cytoplasmic step in the cofactor-trafficking pathway. It catalyzes the glutathione (GSH)-dependent dealkylation of alkylcobalamins and the reductive decyanation of cyanocobalamin. CblC from Caenorhabditis elegans (ceCblC) also exhibits a robust thiol oxidase activity, converting reduced GSH to oxidized GSSG with concomitant scrubbing of ambient dissolved O2 The mechanism of thiol oxidation catalyzed by ceCblC is not known. In this study, we demonstrate that novel coordination chemistry accessible to ceCblC-bound cobalamin supports its thiol oxidase activity via a glutathionyl-cobalamin intermediate. Deglutathionylation of glutathionyl-cobalamin by a second molecule of GSH yields GSSG. The crystal structure of ceCblC provides insights into how architectural differences at the α- and β-faces of cobalamin promote the thiol oxidase activity of ceCblC but mute it in wild-type human CblC. The R161G and R161Q mutations in human CblC unmask its latent thiol oxidase activity and are correlated with increased cellular oxidative stress disease. In summary, we have uncovered key architectural features in the cobalamin-binding pocket that support unusual cob(II)alamin coordination chemistry and enable the thiol oxidase activity of ceCblC.
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Affiliation(s)
- Zhu Li
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600
| | - Aranganathan Shanmuganathan
- the Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814
| | - Markus Ruetz
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600
| | - Kazuhiro Yamada
- the Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814
| | - Nicholas A Lesniak
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600
| | - Bernhard Kräutler
- the Institute of Organic Chemistry and Centre of Molecular Biosciences, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria, and
| | - Thomas C Brunold
- the Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Markos Koutmos
- the Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814
| | - Ruma Banerjee
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600,
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Li Z, Kitanishi K, Twahir UT, Cracan V, Chapman D, Warncke K, Banerjee R. Cofactor Editing by the G-protein Metallochaperone Domain Regulates the Radical B 12 Enzyme IcmF. J Biol Chem 2017; 292:3977-3987. [PMID: 28130442 DOI: 10.1074/jbc.m117.775957] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Indexed: 11/06/2022] Open
Abstract
IcmF is a 5'-deoxyadenosylcobalamin (AdoCbl)-dependent enzyme that catalyzes the carbon skeleton rearrangement of isobutyryl-CoA to butyryl-CoA. It is a bifunctional protein resulting from the fusion of a G-protein chaperone with GTPase activity and the cofactor- and substrate-binding mutase domains with isomerase activity. IcmF is prone to inactivation during catalytic turnover, thus setting up its dependence on a cofactor repair system. Herein, we demonstrate that the GTPase activity of IcmF powers the ejection of the inactive cob(II)alamin cofactor and requires the presence of an acceptor protein, adenosyltransferase, for receiving it. Adenosyltransferase in turn converts cob(II)alamin to AdoCbl in the presence of ATP and a reductant. The repaired cofactor is then reloaded onto IcmF in a GTPase-gated step. The mechanistic details of cofactor loading and offloading from the AdoCbl-dependent IcmF are distinct from those of the better characterized and homologous methylmalonyl-CoA mutase/G-protein chaperone system.
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Affiliation(s)
- Zhu Li
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600 and
| | - Kenichi Kitanishi
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600 and
| | - Umar T Twahir
- the Department of Physics, Emory University, Atlanta, Georgia 30322-2430
| | - Valentin Cracan
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600 and
| | - Derrell Chapman
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600 and
| | - Kurt Warncke
- the Department of Physics, Emory University, Atlanta, Georgia 30322-2430
| | - Ruma Banerjee
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600 and
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Lussier A, Bastet L, Chauvier A, Lafontaine DA. A kissing loop is important for btuB riboswitch ligand sensing and regulatory control. J Biol Chem 2015; 290:26739-51. [PMID: 26370077 DOI: 10.1074/jbc.m115.684134] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Indexed: 12/18/2022] Open
Abstract
RNA-based genetic regulation is exemplified by metabolite-binding riboswitches that modulate gene expression through conformational changes. Crystal structures show that the Escherichia coli btuB riboswitch contains a kissing loop interaction that is in close proximity to the bound ligand. To analyze the role of the kissing loop interaction in the riboswitch regulatory mechanism, we used RNase H cleavage assays to probe the structure of nascent riboswitch transcripts produced by the E. coli RNA polymerase. By monitoring the folding of the aptamer, kissing loop, and riboswitch expression platform, we established the conformation of each structural component in the absence or presence of bound adenosylcobalamin. We found that the kissing loop interaction is not essential for ligand binding. However, we showed that kissing loop formation improves ligand binding efficiency and is required to couple ligand binding to the riboswitch conformational changes involved in regulating gene expression. These results support a mechanism by which the btuB riboswitch modulates the formation of a tertiary structure to perform metabolite sensing and regulate gene expression.
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Affiliation(s)
- Antony Lussier
- From the Department of Biology, Faculty of Science, RNA Group, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Laurène Bastet
- From the Department of Biology, Faculty of Science, RNA Group, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Adrien Chauvier
- From the Department of Biology, Faculty of Science, RNA Group, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Daniel A Lafontaine
- From the Department of Biology, Faculty of Science, RNA Group, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
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Jost M, Born DA, Cracan V, Banerjee R, Drennan CL. Structural Basis for Substrate Specificity in Adenosylcobalamin-dependent Isobutyryl-CoA Mutase and Related Acyl-CoA Mutases. J Biol Chem 2015; 290:26882-26898. [PMID: 26318610 DOI: 10.1074/jbc.m115.676890] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Indexed: 11/06/2022] Open
Abstract
Acyl-CoA mutases are a growing class of adenosylcobalamin-dependent radical enzymes that perform challenging carbon skeleton rearrangements in primary and secondary metabolism. Members of this class of enzymes must precisely control substrate positioning to prevent oxidative interception of radical intermediates during catalysis. Our understanding of substrate specificity and catalysis in acyl-CoA mutases, however, is incomplete. Here, we present crystal structures of IcmF, a natural fusion protein variant of isobutyryl-CoA mutase, in complex with the adenosylcobalamin cofactor and four different acyl-CoA substrates. These structures demonstrate how the active site is designed to accommodate the aliphatic acyl chains of each substrate. The structures suggest that a conformational change of the 5'-deoxyadenosyl group from C2'-endo to C3'-endo could contribute to initiation of catalysis. Furthermore, detailed bioinformatic analyses guided by our structural findings identify critical determinants of acyl-CoA mutase substrate specificity and predict new acyl-CoA mutase-catalyzed reactions. These results expand our understanding of the substrate specificity and the catalytic scope of acyl-CoA mutases and could benefit engineering efforts for biotechnological applications ranging from production of biofuels and commercial products to hydrocarbon remediation.
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Affiliation(s)
- Marco Jost
- Departments of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - David A Born
- Departments of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; the Graduate Program in Biophysics, Harvard University, Cambridge, Massachusetts 02138
| | - Valentin Cracan
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0600
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0600
| | - Catherine L Drennan
- Departments of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; Departments of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139,.
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Kitanishi K, Cracan V, Banerjee R. Engineered and Native Coenzyme B12-dependent Isovaleryl-CoA/Pivalyl-CoA Mutase. J Biol Chem 2015; 290:20466-76. [PMID: 26134562 DOI: 10.1074/jbc.m115.646299] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Indexed: 11/06/2022] Open
Abstract
Adenosylcobalamin-dependent isomerases catalyze carbon skeleton rearrangements using radical chemistry. We have recently demonstrated that an isobutyryl-CoA mutase variant, IcmF, a member of this enzyme family that catalyzes the interconversion of isobutyryl-CoA and n-butyryl-CoA also catalyzes the interconversion between isovaleryl-CoA and pivalyl-CoA, albeit with low efficiency and high susceptibility to inactivation. Given the biotechnological potential of the isovaleryl-CoA/pivalyl-CoA mutase (PCM) reaction, we initially attempted to engineer IcmF to be a more proficient PCM by targeting two active site residues predicted based on sequence alignments and crystal structures, to be key to substrate selectivity. Of the eight mutants tested, the F598A mutation was the most robust, resulting in an ∼17-fold increase in the catalytic efficiency of the PCM activity and a concomitant ∼240-fold decrease in the isobutyryl-CoA mutase activity compared with wild-type IcmF. Hence, mutation of a single residue in IcmF tuned substrate specificity yielding an ∼4000-fold increase in the specificity for an unnatural substrate. However, the F598A mutant was even more susceptible to inactivation than wild-type IcmF. To circumvent this limitation, we used bioinformatics analysis to identify an authentic PCM in genomic databases. Cloning and expression of the putative AdoCbl-dependent PCM with an α2β2 heterotetrameric organization similar to that of isobutyryl-CoA mutase and a recently characterized archaeal methylmalonyl-CoA mutase, allowed demonstration of its robust PCM activity. To simplify kinetic analysis and handling, a variant PCM-F was generated in which the αβ subunits were fused into a single polypeptide via a short 11-amino acid linker. The fusion protein, PCM-F, retained high PCM activity and like PCM, was resistant to inactivation. Neither PCM nor PCM-F displayed detectable isobutyryl-CoA mutase activity, demonstrating that PCM represents a novel 5'-deoxyadenosylcobalamin-dependent acyl-CoA mutase. The newly discovered PCM and the derivative PCM-F, have potential applications in bioremediation of pivalic acid found in sludge, in stereospecific synthesis of C5 carboxylic acids and alcohols, and in the production of potential commodity and specialty chemicals.
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Affiliation(s)
- Kenichi Kitanishi
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600
| | - Valentin Cracan
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600
| | - Ruma Banerjee
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600
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