Rahisuddin R , Payal Thakur , Narender Kumar, Neha Saini, Shrijta Banerjee, Ravi Pratap Singh, Madhuri Patel, S. Kumaran
{"title":"Multi-oligomeric and catalytically compromised serine acetyltransferase and cysteine regulatory complex of Mycobacterium tuberculosis","authors":"Rahisuddin R , Payal Thakur , Narender Kumar, Neha Saini, Shrijta Banerjee, Ravi Pratap Singh, Madhuri Patel, S. Kumaran","doi":"10.1016/j.biochi.2024.01.009","DOIUrl":null,"url":null,"abstract":"<div><p><span>l</span>-cysteine, a primary building block of mycothiol, plays an essential role in the defense mechanism of <em>Mycobacterium tuberculosis</em> (<em>Mtb</em>). However, it is unclear how <em>Mtb</em> regulates cysteine biosynthesis as no study has reported the cysteine regulatory complex (CRC) in <em>Mtb</em>. Serine acetyltransferase (SAT) and cysteine synthase (CS) interact to form CRC. Although <em>Mt</em>CS has been characterized well, minimal information is available on <em>Mt</em>SAT, which synthesizes, O-acetylserine (OAS), the precursor of cysteine. This study fills the gap and provides experimental evidence for the presence of <em>Mt</em>CRC and a non-canonical multi-oligomeric <em>Mt</em>SAT. We employed multiple analytical methods to characterize the oligomeric and kinetic properties of <em>Mt</em>SAT and <em>Mt</em>CRC. Results show that <em>Mt</em>SAT, lacking >75 N-terminal amino acids exists in three different assembly states; trimer, hexamer, and dodecamer, compared to the single hexameric state of SAT of other bacteria. While hexamers display the highest catalytic turnover, the trimer is the least active. The predominance of trimers at low physiologically relevant concentrations suggests that <em>Mt</em>SAT displays the lowest catalytic potential known. Further, the catalytic potential of <em>Mt</em>SAT is also significantly reduced in CRC state, in contrast to enhanced activity of SAT in CRC of other organisms. Our study provides insights into multi-oligomeric <em>Mt</em>SAT with reduced catalytic potential and demonstrates that both <em>Mt</em>SAT and <em>Mt</em>CS of <em>Mycobacterium</em> interact to form CRC, although with altered catalytic properties. We discuss our results in light of the altered biochemistry of the last step of canonical sulfate-dependent cysteine biosynthesis of <em>Mycobacterium</em>.</p></div>","PeriodicalId":251,"journal":{"name":"Biochimie","volume":"221 ","pages":"Pages 110-124"},"PeriodicalIF":3.3000,"publicationDate":"2024-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Biochimie","FirstCategoryId":"99","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0300908424000270","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
l-cysteine, a primary building block of mycothiol, plays an essential role in the defense mechanism of Mycobacterium tuberculosis (Mtb). However, it is unclear how Mtb regulates cysteine biosynthesis as no study has reported the cysteine regulatory complex (CRC) in Mtb. Serine acetyltransferase (SAT) and cysteine synthase (CS) interact to form CRC. Although MtCS has been characterized well, minimal information is available on MtSAT, which synthesizes, O-acetylserine (OAS), the precursor of cysteine. This study fills the gap and provides experimental evidence for the presence of MtCRC and a non-canonical multi-oligomeric MtSAT. We employed multiple analytical methods to characterize the oligomeric and kinetic properties of MtSAT and MtCRC. Results show that MtSAT, lacking >75 N-terminal amino acids exists in three different assembly states; trimer, hexamer, and dodecamer, compared to the single hexameric state of SAT of other bacteria. While hexamers display the highest catalytic turnover, the trimer is the least active. The predominance of trimers at low physiologically relevant concentrations suggests that MtSAT displays the lowest catalytic potential known. Further, the catalytic potential of MtSAT is also significantly reduced in CRC state, in contrast to enhanced activity of SAT in CRC of other organisms. Our study provides insights into multi-oligomeric MtSAT with reduced catalytic potential and demonstrates that both MtSAT and MtCS of Mycobacterium interact to form CRC, although with altered catalytic properties. We discuss our results in light of the altered biochemistry of the last step of canonical sulfate-dependent cysteine biosynthesis of Mycobacterium.
期刊介绍:
Biochimie publishes original research articles, short communications, review articles, graphical reviews, mini-reviews, and hypotheses in the broad areas of biology, including biochemistry, enzymology, molecular and cell biology, metabolic regulation, genetics, immunology, microbiology, structural biology, genomics, proteomics, and molecular mechanisms of disease. Biochimie publishes exclusively in English.
Articles are subject to peer review, and must satisfy the requirements of originality, high scientific integrity and general interest to a broad range of readers. Submissions that are judged to be of sound scientific and technical quality but do not fully satisfy the requirements for publication in Biochimie may benefit from a transfer service to a more suitable journal within the same subject area.