Structural highlights
Publication Abstract from PubMedThe increasing incidence of community- and hospital-acquired infections with multidrug-resistant (MDR) bacteria poses a critical threat to public health and the healthcare system. Although beta-lactam antibiotics are effective against most bacterial infections, some bacteria are resistant to beta-lactam antibiotics by producing beta-lactamases. Among beta-lactamases, metallo-beta-lactamases (MBLs) are especially worrisome as only a few inhibitors have been developed against them. In MBLs, the metal ions play an important role as they coordinate a catalytic water molecule that hydrolyzes beta-lactam rings. We determined the crystal structures of different variants of PNGM-1, an ancient MBL with additional tRNase Z activity. The variants were generated by site-directed mutagenesis targeting metal-coordinating residues. In PNGM-1, both zinc ions are coordinated by six coordination partners in an octahedral geometry, and the zinc-centered octahedrons share a common face. Structures of the PNGM-1 variants confirm that the substitution of a metal-coordinating residue causes the loss of metal binding and beta-lactamase activity. Compared with PNGM-1, subclass B3 MBLs lack one metal-coordinating residue, leading to a shift in the metal-coordination geometry from an octahedral to tetrahedral geometry. Our results imply that a subtle change in the metal-binding site of MBLs can markedly change their metal-coordination geometry and catalytic activity. Structural Study of Metal Binding and Coordination in Ancient Metallo-beta-Lactamase PNGM-1 Variants.,Park YS, Kim TY, Park H, Lee JH, Nguyen DQ, Hong MK, Lee SH, Kang LW Int J Mol Sci. 2020 Jul 12;21(14). pii: ijms21144926. doi: 10.3390/ijms21144926. PMID:32664695[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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