Affiliation:
1. Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, 94275 Le Kremlin-Bicêtre Cédex, France
Abstract
ABSTRACT
Myroides odoratus
and
Myroides odoratimimus
(formerly designated in a single species as
Flavobacterium odoratum
) are gram-negative aerobes and sources of nosocomial infections in humans. They have variable susceptibility to β-lactams and a decreased susceptibility to carbapenems. Using genomic DNAs of
M. odoratus
CIP 103105 and
M. odoratimimus
CIP 103073 reference strains, shotgun cloning of β-lactamase genes was performed, followed by protein expression in
Escherichia coli
. The deduced amino acid sequences of these β-lactamase genes revealed that TUS-1 and MUS-1 from
M. odoratus
CIP 103105 and
M. odoratimimus
CIP 103073, respectively, shared 73% amino acid identity. Mature proteins TUS-1 and MUS-1, with pI values of 7.8 and 5.2, respectively, had relative molecular masses of ca. 26 kDa. These β-lactamases are members of the subclass B1 of metallo-β-lactamases and are distantly related to other metalloenzymes, being most closely related to IND-1 from
Chryseobacterium indologenes
(42% amino acid identity). However, phylogenic analysis showed that TUS-1 and MUS-1 belong to the same phylogenic lineage of subclass B1 enzymes that groups the subclass B1 β-lactamases of
Flavobacterium
species. Kinetic parameters of purified β-lactamases TUS-1 and MUS-1 detailed their hydrolysis spectra, which encompass most β-lactams except aztreonam. β-Lactamases TUS-1 and MUS-1 were classified in functional subgroup 3a of metalloenzymes. This work further characterizes chromosome-encoded metalloenzymes from
Flavobacteriaceae
species that explain at least part of their intrinsic resistance to β-lactams.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Cited by
74 articles.
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