Salt stress induction of glutamyl endopeptidase biosynthesis in Bacillus intermedius

Bacteria from the genus Bacillus have evolved complicated regulatory networks to be protected from various environmental stresses, including sudden increase in salinity. Among these regulatory mechanisms is the DegS-DegU signal transduction system, which controls degradative enzyme synthesis and is involved in sensing salt stress in Bacillus subtilis. We report the study of biosynthesis regulation of Bacillus intermedius glutamyl endopeptidase under salt stress conditions. Salt stress during growth in medium containing 1-2.5 M NaCl, KCl or disodium succinate leads to the induction of glutamyl endopeptidase. Analysis of the regulatory region of the gene for B. intermedius glutamyl endopeptidase revealed the presence of a tentative target sequence for DegU control, AGATN10TTGAG. For the expression of the glutamyl endopeptidase gene, functional DegU protein is required. Thus, we suggest that expression of the gene for B. intermedius glutamyl endopeptidase may be controlled by a regulatory system analogous to DegS-DegU two-component system in B. subtilis.