Electrostatic Ratchet for Successive Peptide Synthesis in Nonribosomal Molecular Machine RimK.

A nonribosomal peptide-synthesizing molecular machine, RimK, adds l-glutamic acids to the C-terminus of ribosomal protein S6 (RpsF) in vivo and synthesizes poly-α-glutamates in vitro. However, the mechanism of the successive glutamate addition, which is fueled by ATP, remains unclear. Here, we investigate the successive peptide-synthesizing mechanism of RimK via the molecular dynamics (MD) simulation of glutamate binding.

Structural polymorphism of the Escherichia coli poly-α-L-glutamate synthetase RimK.

Bacterial RimK is an enzyme that catalyzes the polyglutamylation of the C-terminus of ribosomal protein S6 and the synthesis of poly-α-L-glutamate peptides using L-glutamic acid. In the present study, the crystal structure of the Escherichia coli RimK protein complexed with the ATP analogue AMP-PNP was determined at 2.05 Å resolution.