The role of trimerization in the osmoregulated betaine transporter BetP

EMBO Rep. 2011 Jun 17;12(8):804-10. doi: 10.1038/embor.2011.102.

Abstract

The osmoregulated betaine transporter BetP is a stable trimer. Structural studies have shown that individual protomers can adopt distinct transport conformations, implying a functional role for the trimeric state in transport, although the role of trimerization in regulation is not yet understood. We designed putative monomeric mutants by molecular-dynamics simulations and in silico alanine-scanning mutagenesis. Several mutants including BetP-W101A/T351A were monomeric in detergent as well as in the membrane, as shown by blue native gel electrophoresis, crosslinking and electron microscopy. This monomeric form retains the ability to accumulate betaine, but is no longer regulated by hyperosmotic shock.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Betaine / metabolism*
  • Biological Transport
  • Carrier Proteins / chemistry*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Escherichia coli / metabolism
  • GABA Plasma Membrane Transport Proteins
  • Models, Molecular
  • Mutation
  • Protein Multimerization
  • Protein Subunits / chemistry
  • Proteolipids / metabolism
  • Structure-Activity Relationship
  • Symporters
  • Tomography, X-Ray Computed / methods
  • Water-Electrolyte Balance

Substances

  • Bacterial Proteins
  • BetP protein, Corynebacterium glutamicum
  • Carrier Proteins
  • GABA Plasma Membrane Transport Proteins
  • Protein Subunits
  • Proteolipids
  • Symporters
  • proteoliposomes
  • betaine plasma membrane transport proteins
  • Betaine