Molecular and biochemical characterization of novel PAM-like MBL variants, PAM-2 and PAM-3, from clinical isolates of Pseudomonas tohonis. (4th July 2022)

• Record Type: Journal Article
• Authors: Yamada, Kageto; Yoshizumi, Ayumi; Nagasawa, Tatsuya; Aoki, Kotaro; Sasaki, Masakazu; Murakami, Hinako; Morita, Toshisuke; Ishii, Yoshikazu; Tateda, Kazuhiro
• Is Part Of: Journal of antimicrobial chemotherapy. Volume 77:Number 9(2022)
• Page Start: 2414
• Page End: 2418
• Publication Date: 2022-07-04
• Subjects: Anti-infective agents -- Periodicals; Chemotherapy -- Periodicals; 615.58
• DOI: 10.1093/jac/dkac210
• Languages: English
• ISSNs: 0305-7453

Abstract

Abstract: Background: There is no comprehensive study on PAM-like MBLs. Objectives: Our aim was to characterize novel B3 MBL variants, PAM-2 and PAM-3, from Pseudomonas tohonis clinical isolates. Methods: We evaluated the antimicrobial susceptibility and the MBL gene composition of three novel P. tohonis clinical isolates identified at a Japanese hospital, using the broth microdilution method and WGS, respectively. We characterized the PAM-2 and PAM-3 proteins using recombinant protein expression and biochemical evaluations. Results: Low carbapenem MICs (meropenem MIC = 0.125–1 mg/L) were observed for all three P. tohonis isolates; however, the isolates produced MBLs. We identified bla PAM-2 and bla PAM-3 as potential genes, belonging to a novel subclass of B3 MBLs. Their genomic sequence was similar to that of bla PAM-1 from Pseudomonas alcaligenes . PAM-2 and PAM-3 comprised 287 amino acids and exhibited 90% amino acid identity with PAM-1, 73% identity with POM-1 from Pseudomonas otitidis and 61% identity with L1 from Stenotrophomonas maltophilia . Biochemical evaluations of recombinant PAM-2 and PAM-3 revealed similar k cat / K m ratios and demonstrated catalytic activity against all the tested β-lactams, except for aztreonam. In addition, the k cat / K m ratio for imipenem was 40-fold lower than that for meropenem. Conclusions: P. tohonis harbours a species-specific PAM-family MBL gene. This enzyme has higher hydrolytic activity against meropenem compared with that against imipenem.