Compensating stereochemical changes allow murein tripeptide to be accommodated in a conventional peptide-binding protein.

ABSTRACT: The oligopeptide permease (Opp) of Escherichia coli is an ATP-binding cassette transporter that uses the substrate-binding protein (SBP) OppA to bind peptides and deliver them to the membrane components (OppBCDF) for transport. OppA binds conventional peptides 2-5 residues in length regardless of their sequence, but does not facilitate transport of the cell wall component murein tripeptide (Mtp, L-Ala-γ-D-Glu-meso-Dap), which contains a D-amino acid and a γ-peptide linkage. Instead, MppA, a homologous substrate-binding protein, forms a functional transporter with OppBCDF for uptake of this unusual tripeptide. Here we have purified MppA and demonstrated biochemically that it binds Mtp with high affinity (K(D) ∼ 250 nM). The crystal structure of MppA in complex with Mtp has revealed that Mtp

SUBMITTER: Maqbool A 

PROVIDER: S-EPMC3173086 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature