The tolC homologue of Erwinia chrysanthemi



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Texas Tech University


The tolC gene of £. coli plays a role in bacterial resistance to large hydrophobic reagents. A cosmid (pLAFR1051) fi-om an Erwinia chrysanthemi genomic library capable of rescuing an Escherichia coli mutant sensitive to sodium deoxycholate was identified. Southern analysis identified DNA sequences from this cosmid that hybridized to the E. coli tolC gene. E. coli TolC antiserum was observed to interact in immunoblots with a 46-kDa polypeptide from E. chysanthemi. Cellular fractionation studies localized the polypeptide to the outer membrane of the bacterial cell. Cosmid pLAFR1051 was also observed to encode this polypeptide by immunoblot analysis. Nucleotide sequence analysis of subclones from pLAFR1051 hybridizing to the E. coli tolC gene identified an open reading frame of 1417 base pairs. The deduced amino acid sequence suggests that a polypeptide of 46-kDa could be encoded by this ORE. Analysis of the deduced amino acid sequence indicated the presence of a signal peptide and strong hydrophilic character. The amino acid sequence also indicated 76 % identity to the E. coli TolC protein. The cloned tolC homologue from E. chrysanthemi allowed an E. coli tolC strain to grow on sodium deoxycholate.



Enterobacteriaceae, Escherichia coli, Bacterial diseases of plants, Membrane proteins