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Involvement of a natural transport system in the process of efflux-mediated drug resistance in Mycobacterium smegmatis.

DIR@IMTECH: CSIR-Institute of Microbial Technology

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Title Involvement of a natural transport system in the process of efflux-mediated drug resistance in Mycobacterium smegmatis.
 
Creator Banerjee, S K
Bhatt, K
Misra, P
Chakraborti, Pradip K
 
Subject QR Microbiology
 
Description The phosphate-specific transporter (Pst) in bacteria is a multi-subunit system which belongs to the ABC family of transporters. The gene forms part of an operon and it is involved in phosphate uptake in prokaryotes. Its import function is known to be operative only under conditions of phosphate starvation. However, we found overexpression of this transporter in a Mycobacterium smegmatis strain selected for ciprofloxacin resistance (CIPr) which was grown under conditions in which the phosphate-scavenging function of this operon was inoperative. In CIPr cells, active efflux of the drug plays a predominant role in conferring high levels of fluoroquinolone resistance. We therefore investigated the role of this transporter in the process of efflux-mediated drug resistance by inactivating the pst operon in the CIPr strain. Phenotypic characterization of the resulting strain, CIPrd, showed a striking reduction in the minimal inhibitory concentration (MIC) of ciprofloxacin and in the drug extrusion profile as well. Genotype analysis, on the other hand, revealed partial disruption of the pst operon in CIPrd as a consequence of transporter gene amplification. Furthermore, disruption of this operon in wild-type cells resulted in hypersensitivity to ciprofloxacin and other xenobiotics to which CIPr cells exhibited cross-resistance. Thus our results provide strong evidence that Pst is a natural membrane transport system that has the ability to promote drug efflux in addition to its phosphate-scavenging function in the CIPr strain.
 
Publisher Springer-Verlag
 
Date 2000-01
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://crdd.osdd.net/open/331/1/pchakrabarti2000.pdf
Banerjee, S K and Bhatt, K and Misra, P and Chakraborti, Pradip K (2000) Involvement of a natural transport system in the process of efflux-mediated drug resistance in Mycobacterium smegmatis. Molecular & general genetics : MGG, 262 (6). pp. 949-56. ISSN 0026-8925
 
Relation http://crdd.osdd.net/open/331/