scholarly journals Export of protein in Escherichia coli: a novel mutation in ompC affects expression of other major outer membrane proteins.

1987 ◽  
Vol 169 (9) ◽  
pp. 4327-4334 ◽  
Author(s):  
K M Catron ◽  
C A Schnaitman
Author(s):  
Shuaiyang Wang ◽  
Chunbo You ◽  
Fareed Qumar Memon ◽  
Geyin Zhang ◽  
Yawei Sun ◽  
...  

Abstract The two-component system BaeSR participates in antibiotics resistance of Escherichia coli. To know whether the outer membrane proteins involve in the antibiotics resistance mediated by BaeSR, deletion of acrB was constructed and the recombined plasmid p-baeR was introduced into E. coli K12 and K12△acrB. Minimum inhibitory concentrations (MICs) of antibacterial agents were determined by 2-fold broth micro-dilution method. Gene expressions related with major outer membrane proteins and multidrug efflux pump-related genes were determined by real-time quantitative reverse transcription polymerase chain reaction. The results revealed that the MICs of K12ΔacrB to the tested drugs except for gentamycin and amikacin decreased 2- to 16.75-folds compared with those of K12. When BaeR was overexpressed, the MICs of K12ΔacrB/p-baeR to ceftiofur and cefotaxime increased 2.5- and 2-fold, respectively, compared with their corresponding that of K12△acrB. At the same time, the expression levels of ompC, ompF, ompW, ompA and ompX showed significant reduction in K12ΔacrB/p-baeR as compared with K12△acrB. Moreover, the expression levels of ompR, marA, rob and tolC also significantly ‘decreased’ in K12ΔacrB/p-baeR. These findings indicated that BaeR overproduction can decrease cephalosporins susceptibility in acrB-free E. coli by decreasing the expression level of outer membrane proteins.


2001 ◽  
Vol 47 (8) ◽  
pp. 727-734 ◽  
Author(s):  
Sukumaran Sunil Kumar ◽  
Vasantha Malladi ◽  
Krishnan Sankaran ◽  
Richard Haigh ◽  
Peter Williams ◽  
...  

Enteropathogenic Escherichia coli (EPEC) causes persistent infantile diarrhoea. This nontoxigenic E. coli exhibits a complicated pathogenic mechanism in which its outer membrane proteins and type III secretory proteins damage intestinal epithelium and cause diarrhoea. In accordance with this, our previous study using HEp-2 cells demonstrated cytopathic effects caused by cell-free outer membrane preparations of EPEC. In this study, we report the extrusion of actin-positive strands from HEp-2 and Int 407 cells when treated with outer membrane preparations. An interesting observation of this work, perhaps relevant to the characteristic localized three-dimensional colony formation of EPEC, is the attachment of a wild type EPEC strain to these actin-positive strands.Key words: enteropathogenic Escherichia coli, actin, outer membrane proteins, cytoskeletal elements.


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