Molecular and biochemical heterogeneity of class B carbapenem-hydrolyzing beta-lactamases in Chryseobacterium meningosepticum.
Although the carbapenem-hydrolyzing beta-lactamase (CHbetaL) BlaB-1 is known to be in Chryseobacterium meningosepticum NCTC 10585, a second CHbetaL gene, bla(GOB-1), was cloned from another C. meningosepticum clinical isolate (PINT). The G+C content of bla(GOB-1) (36%) indicated the likely chromosomal origin of this gene. Its expression in Escherichia coli DH10B yields a mature CHbetaL with a pI of 8.7 and a relative molecular mass of 28.2 kDa. In E. coli, GOB-1 conferred resistance to narrow-spectrum cephalosporins and reduced susceptibility to ureidopenicillins, broad-spectrum cephalosporins, and carbapenems. GOB-1 had a broad-spectrum hydrolysis profile including penicillins and cephalosporins (but not aztreonam). The catalytic efficiency for meropenem was higher than for imipenem. GOB-1 had low amino acid identity with the class B CHbetaLs, sharing 18% with the closest, L-1 from Stenotrophomonas maltophilia, and only 11% with BlaB-1. Most of the conserved amino acids that may be involved in the active site of CHbetaLs (His-101, Asp-103, His-162, and His-225) were identified in GOB-1. Sequence heterogeneity was found for GOB-1-like and BlaB-1-like beta-lactamases, having 90 to 100% and 86 to 100% amino acid identity, respectively, among 10 unrelated C. meningosepticum isolates. Each isolate had a GOB-1-like and a BlaB-1-like gene. The same combination of GOB-1-like and BlaB-1-like beta-lactamases was not found in two different isolates. C. meningosepticum is a bacterial species with two types of unrelated chromosome-borne class B CHbetaLs that can be expressed in E. coli and, thus, may represent a clinical threat if spread in gram-negative aerobes.
Bellais
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S
Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, 94275 Le Kremlin-Bicêtre Cedex, France.
Aubert
D
D
Naas
T
T
Nordmann
P
P
D000595:Amino Acid Sequence; D001483:Base Sequence; D015780:Carbapenems / Q000378:metabolism*; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000032:analysis; D005417:Flavobacterium / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D018440:beta-Lactam Resistance / Q000235:genetics*; D001618:beta-Lactamases / Q000145:classification / Q000235:genetics* / Q000378:metabolism
D015780:Carbapenems; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D001618:beta-Lactamases; C558534:beta-lactamase GOB-1, Elizabethkingia meningoseptica