Motion of the zinc ions in catalysis by a dizinc metallo-beta-lactamase.
We report rapid-freeze-quench X-ray absorption spectroscopy of a dizinc metallo-beta-lactamase (MbetaL) reaction intermediate. The Zn(II) ions in the dinuclear active site of the S. maltophilia Class B3 MbetaL move away from each other, by approximately 0.3 A after 10 ms of reaction with nitrocefin, from 3.4 to 3.7 A. Together with our previous characterization of the resting enzyme and its nitrocefin product complex, where the Zn(II) ion separation relaxes to 3.6 A, these data indicate a scissoring motion of the active site that accompanies the ring-opening step. The average Zn(II) coordination number of 4.5 in the resting enzyme appears to be maintained throughout the reaction with nitrocefin. This is the first direct structural information available on early stage dizinc metallo-beta-lactamase catalysis.
Breece
Robert M
RM
Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA.
Hu
Zhenxin
Z
Bennett
Brian
B
Crowder
Michael W
MW
Tierney
David L
DL
D000042:Absorption; D055162:Biocatalysis; D018360:Crystallography, X-Ray; D005583:Fourier Analysis; D009038:Motion; D013057:Spectrum Analysis; D020615:Stenotrophomonas maltophilia / Q000201:enzymology; D015032:Zinc / Q000737:chemistry* / Q000378:metabolism*; D001618:beta-Lactamases / Q000378:metabolism*
D001618:beta-Lactamases; D015032:Zinc