STRUCTURE OF GENES IN A PRESSURE-REGULATED OPERON AND ADJACENT REGIONS FROM A BAROTOLERANT BACTERIUM STRAIN DSS12

A pressure-regulated operon that displayed high homology with one pres ent in the barophilic bacterium strain DB6705 was cloned and sequenced from a barotolerant bacterium strain DSS12. Two open reading frames, ORF1 and ORF2, which constituted the pressure-regulated operon, were i dentified within the sequence, DNA fragments from regions upstream and downstream of the pressure-regulated operon in strain DSS12 were also cloned and sequenced. Downstream of the pressure-regulated operon, th ree open reading frames, designated ORF3, ORF4, and ORF5 were found, a nd part of another ORF, designated UORF6, was located upstream of the operon. From the results of primer extension analysis, the gene expres sions of the pressure-regulated operon (ORF1, 2) and downstream operon (ORF3, 4) were clearly regulated by elevated pressure at the transcri ption level, The deduced amino acid sequences of the gene products of ORF3, 4, 5, and UORF6 showed high homology with CydD, CydC, proline de hydrog enase, and ATP-dependent RNA helicase from Escherichia coli, re spectively. These results indicate that the genes identified in the re gions flanking the pressure-regulated operon are homologous to E. coli genes, although the genes within this operon are not.