Histidine kinase-like ATPase domain of SpoIIAB, an anti sigma-F factor and serine-protein kinase involved in regulating sigma-F during sporulation in Bacilli, and related domains
This family includes histidine kinase-like ATPase (HATPase) domain of SpoIIAB, an anti sigma-F factor and a serine-protein kinase involved in regulating sigma-F during sporulation in Bacilli where, early in sporulation, the cell divides into two unequal compartments: a larger mother cell and a smaller forespore. Sigma-F transcription factor is activated in the forespore directly after the asymmetric septum forms, and its spatial and temporal activation is required for sporulation. Free sigma-F can associate with the RNA polymerase core and activate transcription of the sigma-F regulon, its regulation may comprise a partner-switching mechanism involving SpoIIAB, SpoIIAA, and sigma-F as follows: SpoIIAB can form alternative complexes with either: i) sigma-F, holding it in an inactive form and preventing its association with RNA polymerase, or ii) unphosphorylated SpoIIAA and a nucleotide, either ATP or ADP. In the presence of ATP, SpoIIAB acts as a kinase to specifically phosphorylate a serine residue of SpoIIAA; this phosphorylated form has low affinity for SpoIIAB and dissociates, making SpoIIAB available to capture sigma-F. SpoIIAA may then be dephosphorylated by a SpoIIE serine phosphatase and be free to attack the SpoIIAB sigma-F complex to induce the release of sigma-F.
Comment:based on structures of the HATPase domains of Geobacillus stearothermophilus SpoIIAB, human Hsp90, Escherichia coli DNA gyrase B, and other related proteins, bound with ATP, ADP or their analogs; contacts at 4A
Jiyao W et al.(2023). "The conserved domain database in 2023.",