RsbW phosphorylates AA in the absence of AB. (A) The in vivo ratio of AA to AA-P in a strain lacking σF (KC461 [lane 1]), a strain lacking σF and AB (KC454 [lane 2]), a strain lacking σF, AB, and SpoIIE (KC472 [lane 3]), and a strain lacking σF, AB, SpoIIE, and the entire sigB operon (KC476 [lane 4]). (B) The in vivo ratio of AA to AA-P in strains that lack σF, AB, and SpoIIE and harbor either an intact sigB operon (KC472 [lane 1]), an insertion-deletion of the sigB operon (KC476 [lane 2]), a Campbell disruption of rsbW (KC486 [lane 3]), or an in-frame deletion of rsbT (KC487 [lane 4]). Lysates of cells harvested 90 min after the start of sporulation were subjected to isoelectric focusing followed by immunoblotting with anti-SpoIIAA antibodies.