Mode of Interaction of the Signal-Transducing Protein EIIA(Glc) with the Maltose ABC Transporter in the Process of Inducer Exclusion

Biochemistry. 2016 Sep 27;55(38):5442-52. doi: 10.1021/acs.biochem.6b00721. Epub 2016 Sep 19.

Abstract

Enzyme IIA(Glc) (EIIA(Glc)) of the phosphoenolpyruvate phosphotransferase system for the uptake of glucose in Escherichia coli and Salmonella inhibits the maltose ATP-binding cassette transporter (MalE-FGK2) by interaction with the nucleotide-binding and -hydrolyzing subunit MalK, a process termed inducer exclusion. We have investigated binding of EIIA(Glc) to the MalK dimer by cysteine cross-linking in proteoliposomes. The results prove that the binding site I of EIIA(Glc) is contacting the N-terminal subdomain of MalK while the binding site II is relatively close to the C-terminal (regulatory) subdomain, in agreement with a crystal structure [ Chen , S. , Oldham , M. L. , Davidson , A. L. , and Chen , J. ( 2013 ) Nature 499 , 364 - 368 ]. Moreover, EIIA(Glc) was found to bind to the MalK dimer regardless of its conformational state. Deletion of the amphipathic N-terminal peptide of EIIA(Glc), which is required for inhibition, reduced formation of cross-linked products. Using a spin-labeled transporter variant and EPR spectroscopy, we demonstrate that EIIA(Glc) arrests the transport cycle by inhibiting the ATP-dependent closure of the MalK dimer.

MeSH terms

  • ATP-Binding Cassette Transporters / metabolism*
  • Dimerization
  • Escherichia coli Proteins / metabolism*
  • Maltose / metabolism*
  • Mutagenesis, Site-Directed
  • Protein Binding

Substances

  • ATP-Binding Cassette Transporters
  • Escherichia coli Proteins
  • Maltose