Subdomain II of alpha-Isopropylmalate Synthase Is Essential for Activity INFERRING A MECHANISM OF FEEDBACK INHIBITION

	Subdomain II of alpha-Isopropylmalate Synthase Is Essential for Activity INFERRING A MECHANISM OF FEEDBACK INHIBITION
	Zhang, ZL; Wu, J; Lin, W; Wang, J; Yan, H; Zhao, W; Ma, J; Ding, JP; Zhang, P; Zhao, GP
刊名	JOURNAL OF BIOLOGICAL CHEMISTRY
	2014
卷号	289 期号:40 页码:27966-27978
关键词	Allosteric Regulation Cooperativity Enzyme Catalysis Enzyme Structure Protein Conformation Catalytic Module Feedback Inhibition
通讯作者	Ding, JP (reprint author), Chinese Acad Sci, Shanghai Inst Biol Sci, Inst Biochem & Cell Biol, State Key Lab Mol Biol, Shanghai 200031, Peoples R China.,jpding@sibs.ac.cn ; pengzhang01@sibs.ac.cn ; gpzhao@sibs.ac.cn
英文摘要	Background: Isopropylmalate synthases (IPMSs) with and without a regulatory domain were found. Results: IPMS subdomain II is essential for activities and likely involved in acetyl-CoA binding-mediated conformation transition. Conclusion: The N-terminal domain and the two subdomains comprise the complete and independently functional catalytic module of IPMS. Significance: The IPMS catalytic module was defined and characterized, which inferred a probable feedback inhibition mechanism. The committed step of leucine biosynthesis, converting acetyl-CoA and -ketoisovalerate into -isopropylmalate, is catalyzed by -isopropylmalate synthase (IPMS), an allosteric enzyme subjected to feedback inhibition by the end product l-leucine. We characterized the short form IPMS from Leptospira biflexa (LbIPMS2), which exhibits a catalytic activity comparable with that of the long form IPMS (LbIPMS1) and has a similar N-terminal domain followed by subdomain I and subdomain II but lacks the whole C-terminal regulatory domain. We found that partial deletion of the regulatory domain of LbIPMS1 resulted in a loss of about 50% of the catalytic activity; however, when the regulatory domain was deleted up to Arg-385, producing a protein that is almost equivalent to the intact LbIPMS2, about 90% of the activity was maintained. Moreover, in LbIPMS2 or LbIPMS1, further deletion of several residues from the C terminus of subdomain II significantly impaired or completely abolished the catalytic activity, respectively. These results define a complete and independently functional catalytic module of IPMS consisting of both the N-terminal domain and the two subdomains. Structural comparison of LbIPMS2 and the Mycobacterium tuberculosis IPMS revealed two different conformations of subdomain II that likely represent two substrate-binding states related to cooperative catalysis. The biochemical and structural analyses together with the previously published hydrogen-deuterium exchange data led us to propose a conformation transition mechanism for feedback inhibition mediated by subdomains I and II that might associated with alteration of the binding affinity toward acetyl-CoA.
学科主题	Biochemistry & Molecular Biology
类目[WOS]	Biochemistry & Molecular Biology
关键词[WOS]	TERMINAL REGULATORY DOMAIN ; MYCOBACTERIUM-TUBERCULOSIS ; LEPTOSPIRA-INTERROGANS ; SALMONELLA-TYPHIMURIUM ; SUBSTRATE-SPECIFICITY ; CITRAMALATE SYNTHASE ; HOMOCITRATE SYNTHASE ; CRYSTAL-STRUCTURE ; MOLECULAR-BASIS ; LEUCINE OPERON
收录类别	SCI
语种	英语
WOS记录号	WOS:000342852800050
内容类型	期刊论文
版本	出版稿
源URL	[http://202.127.25.143/handle/331003/271]
专题	上海生化细胞研究所_上海生科院生化细胞研究所
推荐引用方式 GB/T 7714	Zhang, ZL,Wu, J,Lin, W,et al. Subdomain II of alpha-Isopropylmalate Synthase Is Essential for Activity INFERRING A MECHANISM OF FEEDBACK INHIBITION[J]. JOURNAL OF BIOLOGICAL CHEMISTRY,2014,289(40):27966-27978.
APA	Zhang, ZL.,Wu, J.,Lin, W.,Wang, J.,Yan, H.,...&Zhao, GP.(2014).Subdomain II of alpha-Isopropylmalate Synthase Is Essential for Activity INFERRING A MECHANISM OF FEEDBACK INHIBITION.JOURNAL OF BIOLOGICAL CHEMISTRY,289(40),27966-27978.
MLA	Zhang, ZL,et al."Subdomain II of alpha-Isopropylmalate Synthase Is Essential for Activity INFERRING A MECHANISM OF FEEDBACK INHIBITION".JOURNAL OF BIOLOGICAL CHEMISTRY 289.40(2014):27966-27978.