4OV4

Isopropylmalate synthase binding with ketoisovalerate

Summary for 4OV4

• Entry DOI: 10.2210/pdb4ov4/pdb
• Related: 4OV9
• Descriptor: 2-isopropylmalate synthase, ZINC ION, 3-METHYL-2-OXOBUTANOIC ACID, ... (4 entities in total)
• Functional Keywords: alpha/beta tim barrel, transferase
• Biological source: Leptospira biflexa
• Total number of polymer chains: 1
• Total formula weight: 46332.79

Authors

Zhang, Z.,Wu, J.,Wang, C.,Zhang, P. (deposition date: 2014-02-20, release date: 2014-08-20, Last modification date: 2024-03-20)

Primary citation

Zhang, Z.,Wu, J.,Lin, W.,Wang, J.,Yan, H.,Zhao, W.,Ma, J.,Ding, J.,Zhang, P.,Zhao, G.P.
Subdomain II of alpha-isopropylmalate synthase is essential for activity: inferring a mechanism of feedback inhibition.
J.Biol.Chem., 289:27966-27978, 2014

PubMed Abstract: The committed step of leucine biosynthesis, converting acetyl-CoA and α-ketoisovalerate into α-isopropylmalate, is catalyzed by α-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.

PubMed: 25128527
DOI: 10.1074/jbc.M114.559716

Experimental method

X-RAY DIFFRACTION (2 Å)