ISSN:
1432-1432
Keywords:
Key words:Escherichia coli— Multiple resistance — Mar — MarA — MarR —marRAB— XylS
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract. MarA, the 129-amino-acid (aa) protein which plays a crucial role in the multiple antibiotic resistance (Mar) phenotype in Escherichia coli, shows homology to members of the XylS/AraC family of transcriptional regulators. Although these proteins vary in size from around 100 to 350 aa they all contain a DNA-binding domain with a helix-turn-helix motif. The larger ones, e.g., XylS, AraC, and Rob, contain an additional domain either at their amino- or at their carboxy-terminus. This domain is important for effector-binding or dimerization or of unknown function. MarA consists only of the DNA-binding component. Nevertheless, a sequence with a coding potential of 141 aa upstream of its ATG start-codon showed 20.5–26.9% aa identity with the corresponding section within the effector-binding domain of XylS from the TOL plasmid of Pseudomonas putida when translated in the same reading frame as MarA. However, the reading frame was interrupted by 11 translational stops. In another frame, this upstream sequence actually codes for a real protein, MarR, that is completely unrelated to XylS. Implications for the putative evolution of regulatory proteins through translocation of domains followed by adaptation are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00006068
