The physiological roles of SmeIJK and MacABCsm pumps in Stenotrophomonas maltophilia

• Main Authors: Rung-Shiuan Liou, 劉鎔瑄
• Other Authors: Tsuey-Ching Yang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/20907804508873791833

碩士 === 國立陽明大學 === 醫學生物技術暨檢驗學系 === 102 === Stenotrophomonas maltophilia is one of common nosocomial pathogens, which can opportunistically infect immunocompromised patients. Overexpression of multidrug efflux transporters is a critical cause of the bacterial MDR phenotype. In addition to antibiotics extrusion, efflux pumps have also been known to play some physiological roles in the environmental adaption for bacterial survival. This study aims to characterize the physiological roles of two efflux pumps, SmeIJK and MacABCsm in S. maltophilia. In previous study, a physiological role of SmeIJK has been linked to the maintenance of bacterial cell membrane integrity, and σE is involved in the envelope stress response (ESR) in several bacteria. The relation between SmeIJK and σE –dependent ESR was further evaluated by chromosomal and plasmid transcriptional fusion assay. The results demonstrated that (i) The expression of smeIJK was upregulated by membrane damage agents ( MDAs ). (ii) Either smeIJK inactivation or MDAs treatment activated σE-dependent ESR. (iii) MDAs-mediated smeIJK up-expression was σE–dependent. In addition to the known function in antibiotics extrusion, the physiological functions of MacABCsm were further assessed. The function assayed included temperature adaptation, envelope and oxidative stress tolerances, and biofilm formation. The results demonstrated that MacABCsm was involved in envelope and oxidative stress tolerances and biofilm formation, but less related to the growth adaption in different temperature.