IBR   13079
INSTITUTO DE BIOLOGIA MOLECULAR Y CELULAR DE ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effect of remote and second shell mutations in enzymes from the metallo-beta-lactamase superfamily
Autor/es:
ALEJANDRO JOSE VILA
Lugar:
Montevideo
Reunión:
Congreso; 6th International Conference of Biological Physics; 2007
Institución organizadora:
ICBP
Resumen:
Metallo-beta-lactamases (MBLs) are zinc-dependent enzymes able to
hydrolyze all beta-lactam based drugs. They belong to a large superfamily of
metalloenzymes, mostly hydrolases, that employ different metal ions for their
biological roles. Sequence analysis of MBLs reveals a large structural
diversity, that gives rise to the presence of active sites with one and two
metal ions. MBLs also differ from the other members of the large superfamily by
the metal ligands.
Engineering the ligand set
of other members of the superfamily into the MBL from B.cereus (BcII) results in an enzyme with sensibly impaired
catalytic features, that is due to a subtle shift in the position of one metal
ion in the catalytic center.
Directed evolution on BcII
by DNA shuffling resulted in a expanded substrate spectrum of this enzyme,
without sacrificing its stability nor the hydrolytic efficiency towards
classical substrates of BcII. The mutations that give rise to these effects
parallel others naturally found in MBL´s from pathogenic bacteria, and are
related to the second-shell ligands of the second zinc ion, expected to play a
supramolecular control of reactivity.
We have also studied
glyoxalase II from S. typhimurium, a Fe-dependent hydrolase that belongs to the
MBL superfamily. Based on the crystal structure of this enzyme, we propose that
the metal ion selectivity is controled by a second-shell ligand.