Independent patterns of expression of two alternative sigma factors, sigB and sigC, of the myxobacterium Stigmatella aurantiaca during development.

The transcription of many spatially and temporally controlled developmental genes is required for cellular differentiation of the myxobacterium Stigmatella aurantiaca. The expression patterns of the sigma factor gene sigB and of a novel alternative sigma factor gene sigC have been studied during development of Stigmatella aurantiaca. They are expressed at different stages of development. sigB is expressed from the very beginning of fruiting body formation to the sporulation step, while sigC expression takes place later, from the stalk formation to the sporulation step. Neither sigB nor sigC are expressed during heat shock. A sigB mutant and a sigC mutant have been constructed by gene replacement. Their analysis has shown that sigB and sigC expression are independent from each other.