3Q6V

Crystal Structure of Serratia fonticola Sfh-I: glycerol complex

Summary for 3Q6V

• Entry DOI: 10.2210/pdb3q6v/pdb
• Related: 3Q42
• Descriptor: Beta-lactamase, GLYCEROL, ZINC ION, ... (4 entities in total)
• Functional Keywords: metalloenzyme, alpha-beta, metallo-beta-lactamase, hydrolase
• Biological source: Serratia fonticola
• Total number of polymer chains: 2
• Total formula weight: 52904.69

Authors

Fonseca, F.,Saavedra, M.J.,Correia, A.,Spencer, J. (deposition date: 2011-01-03, release date: 2011-07-13, Last modification date: 2024-03-20)

Primary citation

Fonseca, F.,Bromley, E.H.,Saavedra, M.J.,Correia, A.,Spencer, J.
Crystal structure of Serratia fonticola Sfh-I: activation of the nucleophile in mono-zinc metallo-beta-lactamases.
J.Mol.Biol., 411:951-959, 2011

PubMed Abstract: Metallo-β-lactamases (MBLs) or class B β-lactamases are zinc-dependent enzymes capable of inactivating almost all classes of β-lactam antibiotics. To date, no MBL inhibitors are available for clinical use. Of the three MBL subclasses, B2 enzymes, unlike those from subclasses B1 and B3, are fully active with one zinc ion bound and possess a narrow spectrum of activity, hydrolyzing carbapenem substrates almost exclusively. These remain the least studied MBLs. Sfh-I, originally identified from the aquatic bacterium Serratia fonticola UTAD54, is a divergent member of this group. Previous B2 MBL structures, available only for the CphA enzyme from Aeromonas hydrophila, all contain small molecules bound in their active sites. In consequence, the mechanism by which these enzymes activate the water nucleophile required for β-lactam hydrolysis remains to be unambiguously established. Here we report crystal structures of Sfh-I as a complex with glycerol and in the unliganded form, revealing for the first time the disposition of water molecules in the B2 MBL active site. Our data indicate that the hydrolytic water molecule is activated by His118 rather than by Asp120 and/or zinc. Consistent with this proposal, we show that the environment of His118 in B2 MBLs is distinct from that of the B1 and B3 enzymes, where this residue acts as a zinc ligand, and offer a structure-based mechanism for β-lactam hydrolysis by these enzymes.

PubMed: 21762699
DOI: 10.1016/j.jmb.2011.06.043

Experimental method

X-RAY DIFFRACTION (1.37 Å)