Modulation of Escherichia coli serine acetyltransferase catalytic activity in the cysteine synthase complex

FEBS Lett. 2017 May;591(9):1212-1224. doi: 10.1002/1873-3468.12630. Epub 2017 Apr 17.

Abstract

In bacteria and plants, serine acetyltransferase (CysE) and O-acetylserine sulfhydrylase-A sulfhydrylase (CysK) collaborate to synthesize l-Cys from l-Ser. CysE and CysK bind one another with high affinity to form the cysteine synthase complex (CSC). We demonstrate that bacterial CysE is activated when bound to CysK. CysE activation results from the release of substrate inhibition, with the Ki for l-Ser increasing from 4 mm for free CysE to 16 mm for the CSC. Feedback inhibition of CysE by l-Cys is also relieved in the bacterial CSC. These findings suggest that the CysE active site is allosterically altered by CysK to alleviate substrate and feedback inhibition in the context of the CSC.

Keywords: cysteine synthase; protein-protein interaction; serine acetyltransferase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allosteric Regulation
  • Biocatalysis
  • Catalytic Domain
  • Cysteine / metabolism*
  • Cysteine Synthase / metabolism*
  • Enzyme Activation
  • Escherichia coli Proteins / metabolism*
  • Feedback, Physiological
  • Kinetics
  • Protein Binding
  • Serine O-Acetyltransferase / metabolism*
  • Spectrometry, Fluorescence
  • Substrate Specificity

Substances

  • Escherichia coli Proteins
  • CysE protein, E coli
  • Serine O-Acetyltransferase
  • Cysteine Synthase
  • Cysteine