1alq
From Proteopedia
|
CIRCULARLY PERMUTED BETA-LACTAMASE FROM STAPHYLOCOCCUS AUREUS PC1
Overview
The role that domain flexibility plays in the enzymatic activity of, beta-lactamase from Staphylococcus aureus PC1 was investigated by, producing two circularly permuted molecules. The C- and N-termini of the, wild-type enzyme are adjacent to each other and remote from the active, site, which is located between two domains. The polypeptide chain crosses, over from one domain to the other twice. For the circularly permuted, molecules, the termini were joined by an eight amino acid residue, insertion, and new termini were introduced elsewhere. The first construct, termed cp254, was cleaved in a loop remote from the domain interface. The, crystal structure of cp254 has been determined and refined at 1.8 A, resolution, revealing essentially the same structure as that of the native, protein. The activity profile with a representative sample of beta-lactam, antibiotics is also very similar to that of wild-type beta-lactamase. The, termini of the second circularly permuted mutant, cp228, occur within the, second crossover region and therefore may enhance the flexibility of the, molecule. Cp228 beta-lactamase shows a large decrease in enzymatic, activity toward the sample of beta-lactam antibiotics, with catalytic, rates that are 0.5-1% of those of the wild-type enzyme. One exception is, the hydrolysis of the third generation cephalosporin, cefotaxime, which is, hydrolyzed by the cp228 enzyme 10-fold faster than by wild-type, beta-lactamase. Cp228 has not been crystallized. However, the circular, dichroism spectra of the two circularly permuted proteins are very, similar, indicating that, by analogy to cp254, cp228 adopts a global, folded state. Thermal denaturation experiments reveal that cp254 is, somewhat less stable than the wild-type enzyme, whereas cp228 is, substantially less stable. Together, the data highlight the profound, consequences that introducing flexibility at the domain interface has on, both enzyme activity and protein stability.
About this Structure
1ALQ is a Single protein structure of sequence from Staphylococcus aureus with SO4 and CO3 as ligands. Active as Beta-lactamase, with EC number 3.5.2.6 Full crystallographic information is available from OCA.
Reference
Circularly permuted beta-lactamase from Staphylococcus aureus PC1., Pieper U, Hayakawa K, Li Z, Herzberg O, Biochemistry. 1997 Jul 22;36(29):8767-74. PMID:9220963
Page seeded by OCA on Tue Nov 20 10:57:06 2007
