1xp4
From Proteopedia
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Crystal structure of a peptidoglycan synthesis regulatory factor (PBP3) from Streptococcus pneumoniae
Overview
Penicillin-binding proteins (PBPs) are membrane-associated enzymes which, perform critical functions in the bacterial cell division process. The, single d-Ala,d-Ala (d,d)-carboxypeptidase in Streptococcus pneumoniae, PBP3, has been shown to play a key role in control of availability of the, peptidoglycal substrate during cell growth. Here, we have biochemically, characterized and solved the crystal structure of a soluble form of PBP3, to 2.8 A resolution. PBP3 folds into an NH(2)-terminal, d,d-carboxypeptidase-like domain, and a COOH-terminal, elongated beta-rich, region. The carboxypeptidase domain harbors the classic signature of the, penicilloyl serine transferase superfamily, in that it contains a central, five-stranded antiparallel beta-sheet surrounded by alpha-helices. As in, other carboxypeptidases, which are present in species whose peptidoglycan, stem peptide has a lysine residue at the third position, PBP3 has a, 14-residue insertion at the level of its omega loop, a feature that, distinguishes it from carboxypeptidases from bacteria whose peptidoglycan, harbors a diaminopimelate moiety at this position. PBP3 performs substrate, acylation in a highly efficient manner (k(cat)/K(m) = 50,500 M(-1) x, s(-1)), an event that may be linked to role in control of pneumococcal, peptidoglycan reticulation. A model that places PBP3 poised vertically on, the bacterial membrane suggests that its COOH-terminal region could act as, a pedestal, placing the active site in proximity to the peptidoglycan and, allowing the protein to "skid" on the surface of the membrane, trimming, pentapeptides during the cell growth and division processes.
About this Structure
1XP4 is a Single protein structure of sequence from Streptococcus pneumoniae with SO4 and IOD as ligands. Active as Serine-type D-Ala-D-Ala carboxypeptidase, with EC number 3.4.16.4 Full crystallographic information is available from OCA.
Reference
Crystal structure of a peptidoglycan synthesis regulatory factor (PBP3) from Streptococcus pneumoniae., Morlot C, Pernot L, Le Gouellec A, Di Guilmi AM, Vernet T, Dideberg O, Dessen A, J Biol Chem. 2005 Apr 22;280(16):15984-91. Epub 2004 Dec 13. PMID:15596446
Page seeded by OCA on Sun Nov 25 02:37:37 2007
