Spectroscopic signature of a ubiquitous metal binding site in the metallo-B-lactamase superfamily

VALERIA A. CAMPOS-BERMUDEZ; JAVIER MARCELO GONZALEZ; DAVID L. TIERNEY; ALEJANDRO J. VILA

JOURNAL OF BIOLOGICAL CHEMISTRY

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Año: 2010 vol. 15 p. 1209 - 1218

0021-9258

 The metallo-ß-lactamase (MßL) superfamily is a functionally diverse group of metalloproteins sharing a distinctive aß/aß fold and a characteristic metal binding motif. A large number of open reading frames identified in genomic sequencing efforts have been annotated as members of this superfamily through sequence comparisons. However, structural and functional studies performed on purified proteins are normally needed to unequivocally include a newly discovered protein in the MßL superfamily. Here we report the spectroscopic characterization of recombinant YcbL, a gene product annotated as a member of the MßL superfamily whose function in vivo remains unknown. By taking advantage of the structural features characterizing the MßL superfamily metal binding motif, we performed spectroscopic studies on Zn(II)- and Co(II)-substituted YcbL to structurally interrogate the metal binding site. The dinuclear center in Co(II)-YcbL was shown to display characteristic electronic absorption features in the visible region, which were also observed in an engineered MßL aimed at mimicking this metal site. Thus, the spectroscopic features reported herein can be employed as a signature to readily identify and characterize the presence of these ubiquitous metal binding sites.