This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
1g68
From Proteopedia
| Line 1: | Line 1: | ||
[[Image:1g68.jpg|left|200px]] | [[Image:1g68.jpg|left|200px]] | ||
| - | + | <!-- | |
| - | + | The line below this paragraph, containing "STRUCTURE_1g68", creates the "Structure Box" on the page. | |
| - | + | You may change the PDB parameter (which sets the PDB file loaded into the applet) | |
| - | + | or the SCENE parameter (which sets the initial scene displayed when the page is loaded), | |
| - | + | or leave the SCENE parameter empty for the default display. | |
| - | | | + | --> |
| - | | | + | {{STRUCTURE_1g68| PDB=1g68 | SCENE= }} |
| - | + | ||
| - | + | ||
| - | }} | + | |
'''PSE-4 CARBENICILLINASE, WILD TYPE''' | '''PSE-4 CARBENICILLINASE, WILD TYPE''' | ||
| Line 32: | Line 29: | ||
[[Category: Sanschagrin, F.]] | [[Category: Sanschagrin, F.]] | ||
[[Category: Strynadka, N C.J.]] | [[Category: Strynadka, N C.J.]] | ||
| - | [[Category: | + | [[Category: Carbenicillinase]] |
| - | [[Category: | + | [[Category: Class a beta-lactamase]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 17:11:22 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 14:11, 2 May 2008
PSE-4 CARBENICILLINASE, WILD TYPE
Overview
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.
About this Structure
1G68 is a Single protein structure of sequence from Pseudomonas aeruginosa. Full crystallographic information is available from OCA.
Reference
Insights into the molecular basis for the carbenicillinase activity of PSE-4 beta-lactamase from crystallographic and kinetic studies., Lim D, Sanschagrin F, Passmore L, De Castro L, Levesque RC, Strynadka NC, Biochemistry. 2001 Jan 16;40(2):395-402. PMID:11148033 Page seeded by OCA on Fri May 2 17:11:22 2008
