Structural insight into the subclass B1 metallo-β-lactamase AFM-1.

The emergence of drug-resistant bacteria, facilitated by metallo-beta-lactamases (MBLs), presents a significant obstacle to the effective use of antibiotics in the management of clinical drug-resistant bacterial infections. AFM-1 is a MBL derived from Alcaligenes faecalis and shares 86% homology with the NDM-1 family. Both AFM-1 and NDM-1 demonstrate the ability to hydrolyze ampicillin and other β-lactam antibiotics, however, their substrate affinities vary, and the specific reason for this variation remains unknown.

Structural basis for GTP-induced dimerization and antiviral function of guanylate-binding proteins.

Guanylate-binding proteins (GBPs) form a family of dynamin-related large GTPases which mediate important innate immune functions. They were proposed to form oligomers upon GTP binding/hydrolysis, but the molecular mechanisms remain elusive. Here, we present crystal structures of C-terminally truncated human GBP5 (hGBP5), comprising the large GTPase (LG) and middle (MD) domains, in both its nucleotide-free monomeric and nucleotide-bound dimeric states, together with nucleotide-free full-length human GBP2.