1dxk
From Proteopedia
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METALLO-BETA-LACTAMASE FROM BACILLUS CEREUS 569/H/9 C168S MUTANT
Overview
Beta-lactamases are involved in bacterial resistance. Members of the, metallo-enzyme class are now found in many pathogenic bacteria and are, becoming thus of major clinical importance. Despite the availability of, Zn-beta-lactamase X-ray structures their mechanism of action is still, unclear. One puzzling observation is the presence of one or two zincs in, the active site. To aid in assessing the role of zinc content in, beta-lactam hydrolysis, the replacement by Ser of the zinc-liganding, residue Cys168 in the Zn-beta-lactamase from Bacillus cereus strain, 569/H/9 was carried out: the mutant enzyme (C168S) is inactive in the, mono-Zn form, but active in the di-Zn form. The structure of the mono-Zn, form of the C168S mutant has been determined at 1.85 A resolution. Ser168, occupies the same position as Cys168 in the wild-type enzyme. The protein, residues mostly affected by the mutation are Asp90-Arg91 and His210. A, critical factor for the activity of the mono-Zn species is the distance, between Asp90 and the Zn ion, which is controlled by Arg91: a slight, movement of Asp90 impairs catalysis. The evolution of a large superfamily, including Zn-beta-lactamases suggests that they may not all share the same, mechanism.
About this Structure
1DXK is a Single protein structure of sequence from Bacillus cereus with ZN and BCT as ligands. Active as Beta-lactamase, with EC number 3.5.2.6 Structure known Active Site: ZN1. Full crystallographic information is available from OCA.
Reference
Structural effects of the active site mutation cysteine to serine in Bacillus cereus zinc-beta-lactamase., Chantalat L, Duee E, Galleni M, Frere JM, Dideberg O, Protein Sci. 2000 Jul;9(7):1402-6. PMID:10933508
Page seeded by OCA on Mon Nov 5 16:02:07 2007
