The katX gene of Bacillus subtilis is under dual control of σ B and σ F

Publisher Website
Google Scholar
Abstract
The gene katX, which encodes a catalase in Bacillus subtilis, is transcribed by EσF in the pre-spore. This catalase is responsible for the resistance to hydrogen peroxide shown by germinating and outgrowing spores. We demonstrated that katX is also a σB-dependent general stress gene, since it is strongly induced by heat, salt and ethanol stress, as well as by energy depletion. The −10 and −35 sequences of the σB- and σF-dependent promoters of katX overlap, and the transcriptional start points used by EσB and EσF differ by only one nucleotide. Our results indicate that the level of KatX level in outgrowing spores depends mainly on EσF, because sigB mutants show normal KatX activity in dormant and outgrowing spores. katX mutants also develop the non-specific resistance to oxidative stress that is typical of glucose-starved cells. Therefore, the physiological role of σB-dependent katX expression remains obscure. The results indicate an overlap between the σB regulon and the σF regulon, and the physiological implications of this overlap are discussed.