Enzyme structural plasticity and the emergence of broad-spectrum antibiotic resistance.

Frédérique Maurice (1) , Isabelle Broutin (1) , Isabelle Podglajen (2) , Philippe Benas (1) , Ekkehard Collatz (2) , Frédéric Dardel (1)

1 LCRB - UMR 8015 - Laboratoire de cristallographie et RMN biologiques
2 Laboratoire de Recherche Moléculaire sur les Antibiotiques

The emergence of multi-resistant pathogenic bacteria is a worldwide health issue. Recently, clinical variants of a single antibiotic-modifying acetyltransferase, AAC(6')-Ib-a variant of aminoglycoside 6'-N-acetyltransferase-have been identified that confer extended resistance to most aminoglycosides and, more surprisingly, to structurally unrelated fluoroquinolones. The corresponding gene is carried by mobile genetic elements and is present in most multi-resistant pathogenic strains, hence making it a serious threat to current therapies. Here, we report the crystal structures of both narrow- and broad-spectrum resistance variants of this enzyme, which reveal the structural basis for the emergence of extended resistance. The active site shows an important plasticity and has adapted to new substrates by a large-scale gaping process. We have also obtained co-crystals with both substrates, and with a simple transition state analogue, which provides new clues for the design of inhibitors of this resistance mechanism.

Domaines: Biochimie, Biologie Moléculaire

Frédérique Maurice, Isabelle Broutin, Isabelle Podglajen, Philippe Benas, Ekkehard Collatz, et al.. Enzyme structural plasticity and the emergence of broad-spectrum antibiotic resistance.. EMBO Reports, 2008, 9 (4), pp.344-349. ⟨10.1038/embor.2008.9⟩. ⟨hal-00270450⟩