SpoIIAB is an anti-sigma factor that binds to and inhibits transcription by regulatory protein sigma F from Bacillus subtilis.

Abstract

The 0.F factor is a regulatory protein that is responsible for directing gene expression in the forespore compartment of developing cells of the spore-forming soil bacterium BacMlus subtilis. The cJF factor is encoded by the promoter-distal member of sporulation operon spollA, which consists of cistrons called spoIIAA, spollAB, and spollAC. Genetic evidence indicates that the activity of oF is negatively regulated by the product (SpoIIAB) of the spolIAB cistron. We now report that SpoIIAB is capable of binding to cF and inhibiting its capacity to direct transcription by core RNA polymerase from the promoter for a forespore-expressed gene. SpoIIAB is an anti-a factor that may be directly involved in the compartmentalization of arF-directed gene expression.Spore formation in the Gram-positive soil bacterium Bacillus subtilis involves the formation of an asymmetrically positioned septum that partitions the developing cell into two cellular compartments called the forespore and the mother cell (1, 2). Gene expression in the compartments is regulated differentially, with certain genes being expressed in the forespore and others in the mother cell (3, 4). At intermediate to late stages of development, differential gene expression is governed by two compartment-specific RNA polymerase v factors. These are oG, which directs transcription in the forespore, and acK, which directs transcription in the mother cell (5-7). Transcription of the structural genes for crG (spolIIG) and caK (sigK) is, in turn, governed by two earlyacting o factors. These are o7F, which directs the transcription of spoIIIG (8) and other forespore-expressed genes (9), and a'E, which directs the transcription of sigK (10) and other mother-cell-expressed genes (11)(12)(13)(14) 2325The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Four additional genes in the sigB operon of Bacillus subtilis that control activity of the general stress factor sigma B in response to environmental signals

“…One possible explanation for the response of B to these diverse environmental signals comes from work on F , a sporulation-specific transcription factor which is regulated by homologs to RsbV and RsbW (8,14,29,34,45). Alper et al (1) have presented in vitro evidence that these homologs form a sensing system which regulates F activity in response to changes in adenosine nucleotide levels.…”

The Bacillus subtilis rsbU gene product is necessary for RsbX-dependent regulation of sigma B

“…There is compelling evidence that the activities of at least three B. subtilis factors ( B , F , and G ) are controlled by anti-factor proteins (5,12,19,21,22,24). These regulators sequester their target 's into complexes wherein they are unavailable to RNA polymerase (1,5,12,21).…”

“…These regulators sequester their target 's into complexes wherein they are unavailable to RNA polymerase (1,5,12,21). In the cases of F and G , the known regulatory proteins are limited to a common anti-factor, SpoIIAB, and its antagonist, SpoIIAA (1,12,19,21,24). An attractive model has been offered to explain how these proteins interact to control activity.…”

“…Negative regulation of B , like that of at least two other B. subtilis factors ( F and G ) (12,19,21,22), occurs by a specific binding protein (anti-factor) that blocks B from joining to RNA polymerase (5). The anti-B protein (RsbW) is encoded by the second gene of the four-gene operon that includes sigB as its third member (17).…”

Transcription antitermination: the λ paradigm updated

“…The inhibitor itself has not been identified, however, the circumstantial evidence from a number of experiments provides strong support for assuming its existence. The anti-sigma factors (Duncan and Losick, 1993;Ohnishi et al, 1992) offer another example where an inhibitor is part of a regulatory scheme. Obviously, proof of this idea awaits the genetic and functional identification of the inhibitor.…”