1TDG

Complex of S130G SHV-1 beta-lactamase with tazobactam

Summary for 1TDG

• Entry DOI: 10.2210/pdb1tdg/pdb
• Related: 1G56 1RCJ 1SHV 1TDL
• Descriptor: Beta-lactamase SHV-1, CYCLOHEXYL-HEXYL-BETA-D-MALTOSIDE, TAZOBACTAM INTERMEDIATE, ... (7 entities in total)
• Functional Keywords: s130g shv-1 class a beta-lactamase, penicillinase, beta-lactam hydrolase, detergent binding, inhibitor complex, tazobactam, aldehyde, cymal-6, hydrolase
• Biological source: Klebsiella pneumoniae
• Total number of polymer chains: 1
• Total formula weight: 30504.91

Authors

Sun, T.,Bethel, C.R.,Bonomo, R.A.,Knox, J.R. (deposition date: 2004-05-21, release date: 2004-11-23, Last modification date: 2024-11-20)

Primary citation

Sun, T.,Bethel, C.R.,Bonomo, R.A.,Knox, J.R.
Inhibitor-resistant class A beta-lactamases: consequences of the Ser130-to-Gly mutation seen in Apo and tazobactam structures of the SHV-1 variant
Biochemistry, 43:14111-14117, 2004

PubMed Abstract: A bacterial response to the clinical use of class A beta-lactamase inhibitors such as tazobactam and clavulanic acid is the expression of variant beta-lactamases with weaker binding affinities for these mechanism-based inhibitors. Some of these inhibitor-resistant variants contain a glycine mutation at Ser130, a conserved active site residue known to be adventitiously involved in the inhibition mechanism. The crystallographic structure of a complex of tazobactam with the Ser130Gly variant of the class A SHV-1 beta-lactamase has been determined to 1.8 A resolution. Two reaction intermediates are observed. The primary intermediate is an acyclic species bound to the reactive Ser70. It is poorly primed for catalytic hydrolysis because its ester carbonyl group is completely displaced from the enzyme's oxyanion hole. A smaller fraction of the enzyme contains a Ser70-bound aldehyde resulting from hydrolytic loss of the triazoyl-sulfinyl amino acid moiety from the primary species. This first structure of a class A beta-lactamase lacking Ser130, the side chain of which functions in beta-lactam binding and possibly in catalysis, gives crystallographic evidence that the acylation step of beta-lactam turnover can occur without Ser130. Unexpectedly, the crystal structure of the uncomplexed Ser130Gly enzyme, also determined to 1.8 A resolution, shows that a critical Glu166-activated water molecule is missing from the catalytic site. Comparison of this uncomplexed variant with the wild-type structure reveals that Ser130 is required for orienting the side chain of Ser70 and ensuring the hydrogen bonding of Ser70 to both Lys73 and the catalytic water molecule.

PubMed: 15518561
DOI: 10.1021/bi0487903

Experimental method

X-RAY DIFFRACTION (1.8 Å)