Expression ofdnaKandgroESLoperons during sporulation ofBacillus megaterium

Abstract

Expression of the dnaK and groEL genes during sporulation was assayed by determination of their mRNA levels by Northern blotting and compared with the relative level and rate of synthesis of the corresponding proteins. The ability of sporulating cells to respond to a heat shock by an increase in dnaK and groEL expression was determined at the same time. Synthesis of DnaK and GroEL encoding mRNAs during sporulation in non‐shocked cells was low suggesting that this kind of cytodifferentiation was not accompanied by enhanced synthesis of these chaperones. Also the ability of sporulating cells to respond to a heat shock by stimulating their synthesis substantially decreased during the reversible and dropped to negligible values during the irreversible sporulation phase. Nevertheless, some dependence of the heat shock response on sporulation exists because sporulation suppression by mutation or by netropsin treatment further decreased the cells' capacity to respond to a heat shock.