6K8X image
Entry Detail
PDB ID:
6K8X
Keywords:
Title:
Crystal structure of a class C beta lactamase
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2019-06-13
Release Date:
2019-10-16
Method Details:
Experimental Method:
Resolution:
1.59 Å
R-Value Free:
0.20
R-Value Work:
0.18
R-Value Observed:
0.18
Space Group:
C 1 2 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Beta-lactamase
Chain IDs:A
Chain Length:370
Number of Molecules:1
Biological Source:Klebsiella pneumoniae
Primary Citation
Structural Insights into Catalytic Relevances of Substrate Poses in ACC-1.
Antimicrob.Agents Chemother. 63 ? ? (2019)
PMID: 31451494 DOI: 10.1128/AAC.01411-19

Abstact

ACC-1 is a plasmid-encoded class C β-lactamase identified in clinical isolates of Klebsiella pneumoniae, Proteus mirabilis, Salmonella enterica, and Escherichia coli ACC-1-producing bacteria are susceptible to cefoxitin, whereas they are resistant to oxyimino cephalosporins. Here, we depict crystal structures of apo ACC-1, adenylylated ACC-1, and acylated ACC-1 complexed with cefotaxime and cefoxitin. ACC-1 has noteworthy structural alterations in the R2 loop, the Ω loop, and the Phe119 loop located along the active-site rim. The adenylate covalently bonded to the nucleophilic serine reveals a tetrahedral phosphorus mimicking the deacylation transition state. Cefotaxime in ACC-1 has a proper conformation for the substrate-assisted catalysis in that its C-4 carboxylate and N-5 nitrogen are adequately located to facilitate the deacylation reaction. In contrast, cefoxitin in ACC-1 has a distinct conformation, in which those functional groups cannot contribute to catalysis. Furthermore, the orientation of the deacylating water relative to the acyl carbonyl group in ACC-1 is unfavorable for nucleophilic attack.

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