Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Inactivation of MuxABC-OpmB Transporter System in Pseudomonas aeruginosa Leads to Increased Ampicillin and Carbenicillin Resistance and Decreased Virulence: Liang Yang , Lin Chen , Lixin Shen , Michael Surette , Kangmin Duan; J. Microbiol. 2011;49(1):107-114. Published online March 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0186-2

Abstract: Resistance-Nodulation-Cell Division (RND) pumps play important roles in bacterial resistance to antibiotics. Pseudomonas aeruginosa is an important human pathogen which exhibits high level resistance to antibiotics. There are total of 12 RND pumps present in the P. aeruginosa PAO1 genome. The recently characterized MuxABC-OpmB system has been shown to play a role in resistance to novobiocin, aztreonam, macrolides, and tetracycline in a multiple knockout mutation. In this study, we examined the expression levels of all the 12 RND pump gene clusters and tested the involvement of MuxABC-OpmB in pathogenicity. The results indicated that in addition to the four known constitutively expressed RND pumps, mexAB-oprM, mexGHIopmD, mexVW, and mexXY, relatively high levels of expression were observed with mexJK and muxABCopmB in the conditions tested. Inactivation of muxA in the muxABC-opmB operon resulted in elevated resistance to ampicillin and carbenicillin. The mutant also showed attenuated virulence in both Brassica rapa pekinensis and Drosophila melanogaster infection models. The decreased virulence at least in part was due to decreased twitching motility in the mutant. These results indicate that the RND pump MuxABC-OpmB is associated with ampicillin and carbenicillin susceptibility and also involved in pathogenesis in P. aeruginosa.

Functional Analysis of pilQ Gene in Xanthomanas oryzae pv. oryzae, Bacterial Blight Pathogen of Rice: Seon-Hwa Lim , Byoung-Ho So , Ji-Chun Wang , Eun-Seong Song , Young-Jin Park , Byoung-Moo Lee , Hee-Wan Kang; J. Microbiol. 2008;46(2):214-220. Published online June 11, 2008; DOI: https://doi.org/10.1007/s12275-007-0173-9

Abstract: Bacterial blight (BB) of rice, caused by Xanthomonas oryzae pv. oryzae (Xoo), is the most devastating bacterial disease in rice. A virulence-attenuated mutant strain HNU89K9 of X. oryzae pv. oryzae (KACC10331), with a transposon insertion in the pilQ gene was used for this study. The pilQ was involved in the gene cluster pilMNOPQ of the Xoo genome. Growth rate of the pilQ mutant was similar to that of wild-type. At level of amino acids, PilQ of Xoo showed that a high sequence identities more than 94% and 70% to Xanthomonas species and to Xyllela fastidiosa, respectively but a low sequence homology less than 30% to other bacterial species. The twitching motility forming a marginal fringe on PSA media was observed on colony of the wild-type strain KACC10331, but not in mutant HNU89K9. Wild-type Xoo cells formed a biofilm on the surface of the PVC plastic test tube, while the mutant strain HNU89K9 did not form a biofilm. The results suggest that the pilQ gene of X. oryzae pv. oryzae plays a critical role in pathogenicity, twitching motility, and biofilm formation.

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