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Differential binding of Co(II) and Zn(II) to metallo-beta-lactamase Bla2 from Bacillus anthracis. J Am Chem Soc 2009 Aug 05;131(30):10753-62

Date

07/11/2009

Pubmed ID

19588962

Pubmed Central ID

PMC3295577

DOI

10.1021/ja900296u

Scopus ID

2-s2.0-68049106377 (requires institutional sign-in at Scopus site)   39 Citations

Abstract

In an effort to probe the structure, mechanism, and biochemical properties of metallo-beta-lactamase Bla2 from Bacillus anthracis, the enzyme was overexpressed, purified, and characterized. Metal analyses demonstrated that recombinant Bla2 tightly binds 1 equiv of Zn(II). Steady-state kinetic studies showed that mono-Zn(II) Bla2 (1Zn-Bla2) is active, while di-Zn(II) Bla2 (ZnZn-Bla2) was unstable. Catalytically, 1Zn-Bla2 behaves like the related enzymes CcrA and L1. In contrast, di-Co(II) Bla2 (CoCo-Bla2) is substantially more active than the mono-Co(II) analogue. Rapid kinetics and UV-vis, (1)H NMR, EPR, and EXAFS spectroscopic studies show that Co(II) binding to Bla2 is distributed, while EXAFS shows that Zn(II) binding is sequential. To our knowledge, this is the first documented example of a Zn enzyme that binds Co(II) and Zn(II) via distinct mechanisms, underscoring the need to demonstrate transferability when extrapolating results on Co(II)-substituted proteins to the native Zn(II)-containing forms.

Author List

Hawk MJ, Breece RM, Hajdin CE, Bender KM, Hu Z, Costello AL, Bennett B, Tierney DL, Crowder MW

Author

Brian Bennett D.Phil. Professor and Chair in the Physics department at Marquette University




MESH terms used to index this publication - Major topics in bold

Bacillus anthracis
Cobalt
Kinetics
Protein Binding
Recombinant Proteins
Spectrum Analysis
Substrate Specificity
Zinc
beta-Lactamases