UNCOVERING THE TRANSCRIPTIONAL REGULATION OF CLPC DURING SPORULATION IN BACILLUS SUBTILIS

Abstract

ClpC is a AAA+ ATPase chaperone/unfoldase that interacts with the ClpP protease during proteolysis in the gram-positive bacterium Bacillus subtilis. ClpC has roles in several cellular processes including sporulation, cell competence, cell division, and degradative enzyme production. ClpC, while present during normal growth, is known to be produced in high quantities under stressful conditions to degrade protein aggregates. It has been shown previously that ClpCP preferentially localizes to the forespore during sporulation. However, very little is known about the spatial and temporal regulation of ClpC during sporulation. A few putative sporulation-specific promoters have been suggested by in silico predictive analyses, but no specific transcriptional regulators have been defined to date. We used PCR to amplify increasing amount of DNA upstream of clpC (each sequence encompassing different numbers of putative promoters) and cloned the DNA into a plasmid containing lacZ. Newly formed plasmids were transformed into B. subtilis and tested for β-galactosidase activity during sporulation. An increase in β-galactosidase activity around the second hour of sporulation coinciding with the time σH is active was observed. A knockout mutant of this sigma factor eliminated this activity. Another sigma factor, σF, is also active during this time. However, a knockout mutant of sigF did not show any significant difference in gene expression. Altogether, these results suggest that ClpC is at least partially under the control of a σH promoter during sporulation.