1ehi
From Proteopedia
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'''D-ALANINE:D-LACTATE LIGASE (LMDDL2) OF VANCOMYCIN-RESISTANT LEUCONOSTOC MESENTEROIDES''' | '''D-ALANINE:D-LACTATE LIGASE (LMDDL2) OF VANCOMYCIN-RESISTANT LEUCONOSTOC MESENTEROIDES''' | ||
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[[Category: Walsh, C T.]] | [[Category: Walsh, C T.]] | ||
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Revision as of 12:06, 2 May 2008
D-ALANINE:D-LACTATE LIGASE (LMDDL2) OF VANCOMYCIN-RESISTANT LEUCONOSTOC MESENTEROIDES
Overview
BACKGROUND: The bacterial cell wall and the enzymes that synthesize it are targets of glycopeptide antibiotics (vancomycins and teicoplanins) and beta-lactams (penicillins and cephalosporins). Biosynthesis of cell wall peptidoglycan requires a crosslinking of peptidyl moieties on adjacent glycan strands. The D-alanine-D-alanine transpeptidase, which catalyzes this crosslinking, is the target of beta-lactam antibiotics. Glycopeptides, in contrast, do not inhibit an enzyme, but bind directly to D-alanine-D-alanine and prevent subsequent crosslinking by the transpeptidase. Clinical resistance to vancomycin in enterococcal pathogens has been traced to altered ligases producing D-alanine-D-lactate rather than D-alanine-D-alanine. RESULTS: The structure of a D-alanine-D-lactate ligase has been determined by multiple anomalous dispersion (MAD) phasing to 2.4 A resolution. Co-crystallization of the Leuconostoc mesenteroides LmDdl2 ligase with ATP and a di-D-methylphosphinate produced ADP and a phosphinophosphate analog of the reaction intermediate of cell wall peptidoglycan biosynthesis. Comparison of this D-alanine-D-lactate ligase with the known structure of DdlB D-alanine-D-alanine ligase, a wild-type enzyme that does not provide vancomycin resistance, reveals alterations in the size and hydrophobicity of the site for D-lactate binding (subsite 2). A decrease was noted in the ability of the ligase to hydrogen bond a substrate molecule entering subsite 2. CONCLUSIONS: Structural differences at subsite 2 of the D-alanine-D-lactate ligase help explain a substrate specificity shift (D-alanine to D-lactate) leading to remodeled cell wall peptidoglycan and vancomycin resistance in Gram-positive pathogens.
About this Structure
1EHI is a Single protein structure of sequence from Leuconostoc mesenteroides. Full crystallographic information is available from OCA.
Reference
Enzymes of vancomycin resistance: the structure of D-alanine-D-lactate ligase of naturally resistant Leuconostoc mesenteroides., Kuzin AP, Sun T, Jorczak-Baillass J, Healy VL, Walsh CT, Knox JR, Structure. 2000 May 15;8(5):463-70. PMID:10801495 Page seeded by OCA on Fri May 2 15:06:45 2008
