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Use of ferrous iron by metallo-β-lactamases

DOI: 10.1016/j.jinorgbio.2016.07.013 DOI Help

Authors: Samuel T. Cahill (Chemistry Research Laboratory, Oxford) , Hanna Tarhonskaya (Chemistry Research Laboratory, Oxford) , Anna M. Rydzik (Chemistry Research Laboratory, Oxford) , Emily Flashman (Chemistry Research Laboratory, Oxford) , Michael A. Mcdonough (Chemistry Research Laboratory, Oxford) , Christopher J. Schofield (Chemistry Research Laboratory, Oxford) , Jurgen Brem (Chemistry Research Laboratory, Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Inorganic Biochemistry , VOL 163 , PAGES 185 - 193

State: Published (Approved)
Published: October 2016

Open Access Open Access

Abstract: Metallo-β-lactamases (MBLs) catalyse the hydrolysis of almost all β-lactam antibacterials including the latest generation carbapenems and are a growing worldwide clinical problem. It is proposed that MBLs employ one or two zinc ion cofactors in vivo. Isolated MBLs are reported to use transition metal ions other than zinc, including copper, cadmium and manganese, with iron ions being a notable exception. We report kinetic and biophysical studies with the di-iron(II)-substituted metallo-β-lactamase II from Bacillus cereus (di-Fe(II) BcII) and the clinically relevant B1 subclass Verona integron-encoded metallo-β-lactamase 2 (di-Fe(II) VIM-2). The results reveal that MBLs can employ ferrous iron in catalysis, but with altered kinetic and inhibition profiles compared to the zinc enzymes. A crystal structure of di-Fe(II) BcII reveals only small overall changes in the active site compared to the di-Zn(II) enzyme including retention of the di-metal bridging water; however, the positions of the metal ions are altered in the di-Fe(II) compared to the di-Zn(II) structure. Stopped-flow analyses reveal that the mechanism of nitrocefin hydrolysis by both di-Fe(II) BcII and di-Fe(II) VIM-2 is altered compared to the di-Zn(II) enzymes. Notably, given that the MBLs are the subject of current medicinal chemistry efforts, the results raise the possibility the Fe(II)-substituted MBLs may be of clinical relevance under conditions of low zinc availability, and reveal potential variation in inhibitor activity against the differently metallated MBLs.

Journal Keywords: Antibiotic resistance; β-Lactam antibiotics; Metallo-β-lactamase; Zinc hydrolase; Metalloenzyme; Carbapenem

Subject Areas: Chemistry, Biology and Bio-materials


Instruments: I02-Macromolecular Crystallography

Documents:
1-s2.0-S0162013416302148-main.pdf