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Importance of lipooligosaccharide structure in determining gonococcal resistance to hydrophobic antimicrobial agents resulting from the mtr efflux system.
- Source :
- Molecular Microbiology; Jun1995, Vol. 16 Issue 5, p1001-1009, 9p, 1 Diagram, 3 Charts, 2 Graphs
- Publication Year :
- 1995
-
Abstract
- Levels of gonococcal resistance to antimicrobial hydrophobic agents (HAs) are controlled by the <em>mtr</em> (multiple transferrable resistance) system, composed of the <em>mtrRCDE</em> genes. The <em>mtrR</em> gene encodes a transcriptional repressor that appears to regulate expression of the upstream and divergent <em>mtrCDE</em> operon. The <em>mtrCDE</em> genes encode membrane proteins analogous to the MexABOprK proteins of <em>Pseudomonas aeruginosa</em> that mediate export of structuralry diverse antimicrobial agents. In this study we found that a single base pair deletion in a 13bp inverted repeat sequence within the <em>mtrR</em> promoter resulted in increased resistance of gonococci to both crystal violet (CV) and erythromycin (ERY) as well as to the more lipophitic non-ionic detergent Triton X-100 (TX-100). However, this cross-resistance was contingent on the production of a full-length lipooligosaccharide (LOS) by the recipient strain used in transformation experiments. Introduction of this mutation (<em>mtrR-171</em>) into three chemically distinct deep-rough LOS mutants by transformation resulted in a fourfold increase in resistance to TX-100 compared with a 160-fold increase in an isogenic strain producing a full-length LOS. However, both wild-type and deep-rough LOS strains exhibited an eightfold Increase in resistance to CV and ERY as a result of the <em>mtrR-171</em> mutation. This suggests that gonococci have different LOS structural requirements for <em>mtr</em>-mediated resistance to HAs that differ in their lipophilic properties, Evidence is presented that gonococci exclude HAs by an energy-dependent efflux process mediated by the <em>mtr</em> system. [ABSTRACT FROM AUTHOR]
- Subjects :
- PROTEINS
OPERONS
PSEUDOMONAS aeruginosa
GENETIC regulation
MOLECULAR genetics
Subjects
Details
- Language :
- English
- ISSN :
- 0950382X
- Volume :
- 16
- Issue :
- 5
- Database :
- Complementary Index
- Journal :
- Molecular Microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 16126040
- Full Text :
- https://doi.org/10.1111/j.1365-2958.1995.tb02325.x