INDEPENDENT PATTERNS OF EXPRESSION OF 2 ALTERNATIVE SIGMA-FACTORS, SIGB AND SIGC, OF THE MYXOBACTERIUM STIGMATELLA-AURANTIACA DURING DEVELOPMENT

The transcription of many spatially and temporally controlled developm ental genes is required for cellular differentiation of the myxobacter ium Stigmatella aurantiaca. The expression patterns of the sigma facto r gene sigB and of a novel alternative sigma factor gene sigC have bee n studied during development of Stigmatella aurantiaca. They are expre ssed at different stages of development. sigB is expressed from the ve ry beginning of fruiting body formation to the sporulation step, while sigC expression takes place later, from the stalk formation to the sp orulation step. Neither sigB nor sigC are expressed during heat shock. A sigB mutant and a sigC mutant have been constructed by gene replace ment. Their analysis has shown that sigB and sigC expression are indep endent from each other.