Dataset Information

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 ?2?2 and ?6?6 loops in the alpha subunit of tryptophan synthase (?TS) are important for enzyme catalysis and coordinating substrate channeling with the beta subunit (?TS). It was previously shown that disrupting the hydrogen bond interactions between these loops through the T183V substitution on the ?6?6 loop decreases catalytic efficiency and impairs substrate channeling. Results presented here also indicate that the T183V substitution decreases catalytic efficiency in Escherchia coli ?TS in the absence of the ?TS subunit. Nuclear magnetic resonance (NMR) experiments indicate that the T183V substitution leads to local changes in the structural dynamics of the ?2?2 and ?6?6 loops. We have also used NMR chemical shift covariance analyses (CHESCA) to map amino acid networks in the presence and absence of the T183V substitution. Under conditions of active catalytic turnover, the T183V substitution disrupts long-range networks connecting the catalytic residue Glu49 to the ?TS-?TS binding interface, which might be important in the coordination of catalytic activities in the tryptophan synthase complex. The approach that we have developed here will likely find general utility in understanding long-range impacts on protein structure and dynamics of amino acid substitutions generated through protein engineering and directed evolution approaches, and provide insight into disease and drug-resistance mutations.

SUBMITTER: Axe JM

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

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

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

Axe Jennifer M JM O'Rourke Kathleen F KF Kerstetter Nicole E NE Yezdimer Eric M EM Chan Yan M YM Chasin Alexander A Boehr David D DD

Protein science : a publication of the Protein Society 20141211 4

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 efficienc ...[more]

PMID: 25377949

Similar Datasets

Project description:Hydrogen-bonding networks in proteins considered as structural tensile elements are in balance separately from any other stabilising interactions that may be in operation. The hydrogen bond arrangement in the network is reminiscent of tensegrity structures in architecture and sculpture. Tensegrity has been discussed before in cells and tissues and in proteins. In contrast to previous work only hydrogen bonds are studied here. The other interactions within proteins are either much stronger - covalent bonds connecting the atoms in the molecular skeleton or weaker forces like the so-called hydrophobic interactions. It has been demonstrated that the latter operate independently from hydrogen bonds. Each category of interaction must, if the protein is to have a stable structure, balance out. The hypothesis here is that the entire hydrogen bond network is in balance without any compensating contributions from other types of interaction. For sidechain-sidechain, sidechain-backbone and backbone-backbone hydrogen bonds in proteins, tensegrity balance ("closure") is required over the entire length of the polypeptide chain that defines individually folding units in globular proteins ("domains") as well as within the repeating elements in fibrous proteins that consist of extended chain structures. There is no closure to be found in extended structures that do not have repeating elements. This suggests an explanation as to why globular domains, as well as the repeat units in fibrous proteins, have to have a defined number of residues. Apart from networks of sidechain-sidechain hydrogen bonds there are certain key points at which this closure is achieved in the sidechain-backbone hydrogen bonds and these are associated with demarcation points at the start or end of stretches of secondary structure. Together, these three categories of hydrogen bond achieve the closure that is necessary for the stability of globular protein domains as well as repeating elements in fibrous proteins.

Dataset Information

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

Publications

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

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets