The delta subunit of RNA polymerase functions in sporulation

Purified RNA polymerase from Bacillus subtilis and other Gram-positive organisms contains a novel subunit designated delta encoded by the rpoE gene. There is no distinctive phenotype of strains with a disruption of this gene, so the function of delta is very subtle or redundant. We have found, however, that suppression of a block in sporulation of B. subtilis at early stage III owing to disruption of the pdhC gene encoding the E2 subunit of pyruvate dehydrogenase (PDH) was attributable to a Tn10 insertion in the rpoE gene. An independent disruption of this gene also caused suppression. An earlier sporulation block due to absence of the E1beta subunit of PDH was not suppressed. This specific suppression indicates that the delta subunit does have some direct or indirect role in sporulation, probably in the transcription of selected genes at stage II-III of sporulation, which is critical but only when there is functional E2.