Sequence analysis of PER-1 extended-spectrum beta-lactamase from Pseudomonas aeruginosa and comparison with class A beta-lactamases.
We have determined the nucleotide sequence (EMBL accession number, Z 21957) of the cloned chromosomal PER-1 extended-spectrum beta-lactamase gene from a Pseudomonas aeruginosa RNL-1 clinical isolate, blaPER-1 corresponds to a 924-bp open reading frame which encodes a polypeptide of 308 amino acids. This open reading frame is preceded by a -10 and a -35 region consistent with a putative P. aeruginosa promoter. Primer extension analysis of the PER-1 mRNA start revealed that this promoter was active in P. aeruginosa but not in Escherichia coli, in which PER-1 expression was driven by vector promoter sequences. N-terminal sequencing identified the PER-1 26-amino-acid leader peptide and enabled us to calculate the molecular mass (30.8 kDa) of the PER-1 mature form. Analysis of the percent GC content of blaPER-1 and of its 5' upstream sequences, as well as the codon usage for blaPER-1, indicated that blaPER-1 may have been inserted into P. aeruginosa genomic DNA from a nonpseudomonad bacterium. The PER-1 gene showed very low homology with other beta-lactamase genes at the DNA level. By using computer methods, assessment of the extent of identity between PER-1 and 10 beta-lactamase amino acid sequences indicated that PER-1 is a class A beta-lactamase. PER-1 shares around 27% amino acid identity with the sequenced extended-spectrum beta-lactamases of the TEM-SHV series and MEN-1 from Enterobacteriaceae species. The use of parsimony methods showed that PER-1 is not more closely related to gram-negative than to gram-positive bacterial class A beta-lactamases. Surprisingly, among class A beta-lactamases, PER-1 was most closely related to the recently reported CFXA from Bacteroides vulgatus, with which it shared 40% amino acid identity. This work indicates that non-Enterobacteriaceae species such as P. aeruginosa may possess class A extended-spectrum beta-lactamase genes possibly resulting from intergeneric DNA transfer.
Nordmann
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P
Service de Microbiologie, Hôpital Raymond Poincaré, Faculté de Médecine Paris-Ouest, Université Paris, Garches, France.
Naas
T
T
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis / Q000302:isolation & purification; D004926:Escherichia coli / Q000235:genetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016366:Open Reading Frames; D010957:Plasmids; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D001618:beta-Lactamases / Q000032:analysis* / Q000235:genetics
D003470:Culture Media; D004269:DNA, Bacterial; D001618:beta-Lactamases