Structural and functional characterization of a novel α/β hydrolase from cariogenic pathogen Streptococcus mutans

Proteins. 2014 Apr;82(4):695-700. doi: 10.1002/prot.24418. Epub 2013 Oct 18.

Abstract

The protein Smu.1393c from Streptococcus mutans is annotated as a putative α/β hydrolase, but it has low sequence identity to the structure-known α/β hydrolases. Here we present the crystal structure of Smu.1393c at 2.0 Å resolution. Smu.1393c has a fully open alkaline substrate pocket, whose conformation is unique among other similar hydrolase structures. Three residues, Ser101, His251, and Glu125, were identified as the active center of Smu.1393c. By screening a series of artificial hydrolase substrates, we demonstrated Smu.1393c had low carboxylesterase activity towards short-chain carboxyl esters, which provided a clue for exploring the in vivo function of Smu.1393c.

Keywords: Smu.1393c; X-ray crystallography; cap domain; carboxylesterase; catalytic triad.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / ultrastructure
  • Carboxylic Ester Hydrolases
  • Catalytic Domain
  • Crystallization
  • Crystallography, X-Ray
  • Hydrolases / chemistry*
  • Hydrolases / ultrastructure*
  • Streptococcus mutans / enzymology*

Substances

  • Bacterial Proteins
  • Hydrolases
  • Carboxylic Ester Hydrolases

Associated data

  • PDB/4L9A