Processing of a membrane protein required for cell-to-cell signaling during endospore formation in Bacillus subtilis

TY - JOUR

T1 - Processing of a membrane protein required for cell-to-cell signaling during endospore formation in Bacillus subtilis

AU - Serrano, Mónica

AU - Vieira, Filipe

AU - Moran, Charles P.

AU - Henriques, Adriano O.

PY - 2008/12

Y1 - 2008/12

N2 - Activation of the late prespore-specific RNA polymerase sigma factor σG during Bacillus subtilis sporulation coincides with completion of the engulfment process, when the prespore becomes a protoplast fully surrounded by the mother cell cytoplasm and separated from it by a double membrane system. Activation of σG also requires expression of spoIIIJ, coding for a membrane protein translocase of the YidC/Oxa1p/Alb3 family, and of the mother cell-specific spoIIIA operon. Here we present genetic and biochemical evidence indicating that SpoIIIAE, the product of one of the spoIIIA cistrons, and SpoIIIJ interact in the membrane, thereby linking the function of the spoIIIJ and spoIIIA loci in the activation of σG. We also show that SpoIIIAE has a functional Sec-type signal peptide, which is cleaved during sporulation. Furthermore, mutations that reduce or eliminate processing of the SpoIIIAE signal peptide arrest sporulation following engulfment completion and prevent activation of σG. SpoIIIJ-type proteins can function in cooperation with or independently of the Sec system. In one model, SpoIIIJ interacts with SpoIIIAE in the context of the Sec translocon to promote its correct localization and/or topology in the membrane, so that it can signal the activation of σG following engulfment completion.

AB - Activation of the late prespore-specific RNA polymerase sigma factor σG during Bacillus subtilis sporulation coincides with completion of the engulfment process, when the prespore becomes a protoplast fully surrounded by the mother cell cytoplasm and separated from it by a double membrane system. Activation of σG also requires expression of spoIIIJ, coding for a membrane protein translocase of the YidC/Oxa1p/Alb3 family, and of the mother cell-specific spoIIIA operon. Here we present genetic and biochemical evidence indicating that SpoIIIAE, the product of one of the spoIIIA cistrons, and SpoIIIJ interact in the membrane, thereby linking the function of the spoIIIJ and spoIIIA loci in the activation of σG. We also show that SpoIIIAE has a functional Sec-type signal peptide, which is cleaved during sporulation. Furthermore, mutations that reduce or eliminate processing of the SpoIIIAE signal peptide arrest sporulation following engulfment completion and prevent activation of σG. SpoIIIJ-type proteins can function in cooperation with or independently of the Sec system. In one model, SpoIIIJ interacts with SpoIIIAE in the context of the Sec translocon to promote its correct localization and/or topology in the membrane, so that it can signal the activation of σG following engulfment completion.

UR - http://www.scopus.com/inward/record.url?scp=57349120583&partnerID=8YFLogxK

U2 - 10.1128/JB.00715-08

DO - 10.1128/JB.00715-08

M3 - Journal article

C2 - 18820020

AN - SCOPUS:57349120583

SN - 0021-9193

VL - 190

SP - 7786

EP - 7796

JO - Journal of Bacteriology

JF - Journal of Bacteriology

IS - 23

ER -