Loss of a conserved salt bridge in bacterial glycosyl hydrolase BgIM-G1 improves substrate binding in temperate environments.

ABSTRACT: Salt bridges are the strongest electrostatic interactions in proteins. They substantially contribute to a protein's structural stability. Thus, mutations of salt bridges are typically selected against. Here, we report on the evolutionary loss of a highly conserved salt bridge in the GH1 family glycosyl hydrolase BglM-G1. BglM-G1's gene was found in the bacterial metagenome of a temperate, seasonally cold marine habitat. In BglM-G1, arginine 75 is replaced by a histidine. While fully retaining β-glucosidase activity, BglM-G1 is less heat stable than an H75R variant, in which the salt bridge was artificially re-introduced. However, the K _m toward its substrates was lower in wild type, leading to an overall higher catalytic efficiency. Our results indicate that this l

SUBMITTER: Mhaindarkar D 

PROVIDER: S-EPMC6192996 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature