Clusters of branched aliphatic side chains serve as cores of stability in the native state of the HisF TIM barrel protein.

ABSTRACT: Imidazole-3-glycerol phosphate synthase is a heterodimeric allosteric enzyme that catalyzes consecutive reactions in imidazole biosynthesis through its HisF and HisH subunits. The unusually slow unfolding reaction of the isolated HisF TIM barrel domain from the thermophilic bacteria, Thermotoga maritima, enabled an NMR-based site-specific analysis of the main-chain hydrogen bonds that stabilize its native conformation. Very strong protection against exchange with solvent deuterium in the native state was found in a subset of buried positions in α-helices and pervasively in the underlying β-strands associated with a pair of large clusters of isoleucine, leucine and valine (ILV) side chains located in the α7(βα)8(βα)1-2 and α2(βα)3-6β7 segments of the (βα)8 barrel. The most densely packed re

SUBMITTER: Gangadhara BN 

PROVIDER: S-EPMC3696590 | biostudies-literature | 2013 Mar

REPOSITORIES: biostudies-literature