2hwg

From Proteopedia

Revision as of 09:54, 21 November 2007

Structure of phosphorylated Enzyme I of the phosphoenolpyruvate:sugar phosphotransferase system

Overview

Bacterial transport of many sugars, coupled to their phosphorylation, is, carried out by the phosphoenolpyruvate (PEP):sugar phosphotransferase, system and involves five phosphoryl group transfer reactions. Sugar, translocation initiates with the Mg(2+)-dependent phosphorylation of, enzyme I (EI) by PEP. Crystals of Escherichia coli EI were obtained by, mixing the protein with Mg(2+) and PEP, followed by oxalate, an EI, inhibitor. The crystal structure reveals a dimeric protein where each, subunit comprises three domains: a domain that binds the partner PEP:sugar, phosphotransferase system protein, HPr; a domain that carries the, phosphorylated histidine residue, His-189; and a PEP-binding domain. The, PEP-binding site is occupied by Mg(2+) and oxalate, and the phosphorylated, His-189 is in-line for phosphotransfer to/from the ligand. Thus, the, structure represents an enzyme intermediate just after phosphotransfer, from PEP and before a conformational transition that brings His-189, approximately P in proximity to the phosphoryl group acceptor, His-15 of, HPr. A model of this conformational transition is proposed whereby, swiveling around an alpha-helical linker disengages the His domain from, the PEP-binding domain. Assuming that HPr binds to the HPr-binding domain, as observed by NMR spectroscopy of an EI fragment, a rotation around two, linker segments orients the His domain relative to the HPr-binding domain, so that His-189 approximately P and His-15 are appropriately stationed for, an in-line phosphotransfer reaction.

About this Structure

2HWG is a Single protein structure of sequence from Escherichia coli with MG and OXL as ligands. Active as Phosphoenolpyruvate--protein phosphotransferase, with EC number 2.7.3.9 Full crystallographic information is available from OCA.

Reference

Structure of phosphorylated enzyme I, the phosphoenolpyruvate:sugar phosphotransferase system sugar translocation signal protein., Teplyakov A, Lim K, Zhu PP, Kapadia G, Chen CC, Schwartz J, Howard A, Reddy PT, Peterkofsky A, Herzberg O, Proc Natl Acad Sci U S A. 2006 Oct 31;103(44):16218-23. Epub 2006 Oct 19. PMID:17053069

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