The resistance of bacterial endospores is determined by the function of small acid-soluble spore proteins (SASPs) which bind DNA up to saturation with the effect of DNA protection by densely packaging. During spore outgrowth, SASPs are specifically cleaved by germination proteases (GPRs) and serve as important source of amino acids for the developing new cell.
Here, six putative SASPs of C. acetobutylicum were investigated for the resistance and outgrowth of endospores and two germination proteases were examined for specific SASP cleaving activity.
Taken together, the most important outcome was that C. acetobutylicum spores harbor only one major SASP, which could be identified as SspA and account for 93 % of total spore SASPs. The lost of the SspA showed dramatic consequences for the development of the new outgrowing cell, a hitherto unique example among spore forming bacteria. Furthermore, enzymatic function of GPR and for the first time of germination protease-like activity of an YyaC- protein could be demonstrated.