Differential binding of Co(II) and Zn(II) to metallo-beta-lactamase Bla2 from Bacillus anthracis.
J Am Chem Soc
; 131(30): 10753-62, 2009 Aug 05.
Article
in En
| MEDLINE
| ID: mdl-19588962
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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Bacillus anthracis
/
Zinc
/
Beta-Lactamases
/
Cobalt
Language:
En
Journal:
J Am Chem Soc
Year:
2009
Document type:
Article
Affiliation country:
Estados Unidos