Asp residues of βDELSEED-motif are required for peptide binding in the Escherichia coli ATP synthase

This study demonstrates the requirement of Asp-380 and Asp-386 in the beta DELSEED-motif of Escherichia coli ATP synthase for peptide binding and inhibition. We studied the inhibition profiles of wild-type and mutant E. coli ATP synthase in presence of c-terminal amide bound melittin and melittin related peptide. Melittin and melittin related peptide inhibited wild-type ATPase almost completely while only partial inhibition was observed in single mutations with replacement of Asp to Ala, Gin, or Arg. Additionally, very little or no inhibition occurred among double mutants beta D380A/beta D386A, beta D3800/beta D386Q or beta D380R/beta D386R signifying that removal of one Asp residue allows limited peptide binding. Partial or substantial loss of oxidative phosphorylation among double mutants demonstrates the functional requirement of beta D380 and PD386 Asp residues. Moreover, abrogation of wild-type E. coli cell growth and normal growth of mutant cells in presence of peptides provides strong evidence for the requirement of beta DELSEED-motif Asp residues for peptide binding. It is concluded that while presence of one Asp residue may allow partial peptide binding, both Asp residues, beta D380 and beta D386, are essential for proper peptide binding and inhibition of ATP synthase. (C) 2015 Elsevier B.V. All rights reserved.