1G68

PSE-4 CARBENICILLINASE, WILD TYPE

1G68 の概要

• エントリーDOI: 10.2210/pdb1g68/pdb
• 関連するPDBエントリー: 1G6A
• 分子名称: BETA-LACTAMASE PSE-4, SULFATE ION (3 entities in total)
• 機能のキーワード: class a beta-lactamase, carbenicillinase, hydrolase
• 由来する生物種: Pseudomonas aeruginosa
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 29652.24

構造登録者

Lim, D.,Sanschagrin, F.,Passmore, L.,De Castro, L.,Levesque, R.C.,Strynadka, N.C.J. (登録日: 2000-11-03, 公開日: 2001-02-21, 最終更新日: 2024-10-09)

主引用文献

Lim, D.,Sanschagrin, F.,Passmore, L.,De Castro, L.,Levesque, R.C.,Strynadka, N.C.
Insights into the molecular basis for the carbenicillinase activity of PSE-4 beta-lactamase from crystallographic and kinetic studies.
Biochemistry, 40:395-402, 2001

PubMed Abstract: PSE-4 is a class A beta-lactamase produced by strains of Pseudomonas aeruginosa and is highly active for the penicillin derivative carbenicillin. The crystal structure of the wild-type PSE-4 carbenicillinase has been determined to 1.95 A resolution by molecular replacement and represents the first structure of a carbenicillinase published to date. A superposition of the PSE-4 structure with that of TEM-1 shows a rms deviation of 1.3 A for 263 Calpha atoms. Most carbenicillinases are unique among class A beta-lactamases in that residue 234 is an arginine (ABL standard numbering scheme), while in all other class A enzymes this residue is a lysine. Kinetic characterization of a R234K PSE-4 mutant reveals a 50-fold reduction in k(cat)/K(m) and confirms the importance of Arg 234 for carbenicillinase activity. A comparison of the structure of the R234K mutant refined to 1.75 A resolution with the wild-type structure shows that Arg 234 stabilizes an alternate conformation of the Ser 130 side chain, not seen in other class A beta-lactamase structures. Our molecular modeling studies suggest that the position of a bound carbenicillin would be shifted relative to that of a bound benzylpenicillin in order to avoid a steric clash between the carbenicillin alpha-carboxylate group and the conserved side chain of Asn 170. The alternate conformation of the catalytic Ser 130 in wild-type PSE-4 may be involved in accommodating this shift in the bound substrate position.

PubMed: 11148033
DOI: 10.1021/bi001653v

実験手法

X-RAY DIFFRACTION (1.95 Å)