Analysis of cis-elements upstream of the pressure-regulated operon in the deep-sea barophilic bacterium Shewanella violacea strain DSS12

Potential regulatory elements were identified upstream of the pressure-regu lated operon in the deep-sea barophilic bacterium Shewanella violacea strai n DSS12 and binding of cellular proteins to this region was studied under d ifferent pressure conditions. Sequence analysis revealed the existence of a region, designated region A, showing similarity to the consensus sequence for sigma(54) binding, when the region upstream of the operon was compared with several consensus sequences for sigma factors. A palindromic sequence AGTTAAAGATTAAACT, designated region B, was found further upstream beyond re gion A. In a region designated region C, just upstream of region B; a uniqu e octamer motif AAGGTAAG, tandemly repeated 13 times, was found. By means o f an electrophoretic mobility shift assay it was demonstrated that a sigma( 54)-like factor recognized region A while other unknown factors recognized the sequences in regions B and C. Different shift patterns of protein-DNA c omplexes were observed when extracts of cells cultured at 0.1 MPa and 50 MP a were incubated with P-32-labeled DNA probes corresponding to region B or C. These results indicate that barophilic strain DSS12 expresses different DNA-binding factors capable of recognizing these elements upstream of the p ressure-regulated operon under different pressure conditions. (C) 1999 Fede ration of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.