Severing of a hydrogen bond disrupts amino acid networks in the catalytically active state of the alpha subunit of tryptophan synthase.

ABSTRACT: Conformational changes in the β2α2 and β6α6 loops in the alpha subunit of tryptophan synthase (αTS) are important for enzyme catalysis and coordinating substrate channeling with the beta subunit (βTS). It was previously shown that disrupting the hydrogen bond interactions between these loops through the T183V substitution on the β6α6 loop decreases catalytic efficiency and impairs substrate channeling. Results presented here also indicate that the T183V substitution decreases catalytic efficiency in Escherchia coli αTS in the absence of the βTS subunit. Nuclear magnetic resonance (NMR) experiments indicate that the T183V substitution leads to local changes in the structural dynamics of the β2α2 and β6α6 loops. We have also used NMR chemical shift covariance analyses (CHESCA) to map amino a

SUBMITTER: Axe JM 

PROVIDER: S-EPMC4380980 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature