ATPase. Has a role at an early stage in the morphogenesis of the spore coat outer layers. Its ATP hydrolysis is required for proper assembly of the spore coat. Forms a basement layer around the outside surface of the forespore and self-assembles irreversibly into higher order structures by binding and hydrolyzing ATP thus creating a durable and stable platform upon which thereafter morphogenesis of the coat can take place. Required for proper localization of spore coat protein CotE and sporulation-specific proteins including SpoVM. ATP + H2O = ADP + H(+) + phosphate The turnover rate is 2.7 pmol/min/pmol of SpoIVA at Vmax (PubMed:18691972). The turnover rate is 1.0 pmol/min/pmol of SpoIVA at Vmax (PubMed:23267091). Polymerizes to self-assemble into static filaments. ATP hydrolysis is required by every subunit for incorporation into the growing polymer by inducing a conformational change that drives polymerization of a nucleotide-free filament. Polymerization requires a critical concentration of the protein and only occurs after it is localized to the surface of the developing spore. Interacts (via extreme C-terminus Gly-486) with SpoVM (via Ile-6). Interacts (via full-length) with SpoVID (via C-terminus 499-575 AA). Interacts with SafA. Uniformly distributed on the membrane around the forespore, lying close to or on its outer surface. Expression only necessary in the mother cell chamber of the sporangium for the formation of a mature spore. According to PubMed:8299942, not a coat protein of the mature spore, is only transiently associated with the assembling coat. According to PubMed:9922240, present as a component of the fully mature spore. Proper localization requires the expression of a gene spoVM which is under the control of the mother cell transcription factor sigma E. Expressed soon after the formation of the asymmetric septum during sporulation. Expression commences about 2 hours after the onset of sporulation. Assembly around the developing forespore commences at the time of polar division and seems to continue after engulfment of the forespore is complete. Remains present throughout the late stages of morphogenesis and during this accumulation process preferentially collects on the mother cell side of the engulfed forespore, but eventually is deposited equally all around the forespore. Extreme C-terminal region (AA 487-492) is required for its proper localization into a spherical shell around the developing forespore. N-terminus (AA 1-64) is functionally important although largely dispensable for proper localization. Seems to be cleaved by the YabG protease. Forespores lack a well-defined cortex, and the coat is present as swirls in the mother cell compartment of the sporangia rather than having been deposited around the forespore protoplasts. According to PubMed:18691972, unable to sporulate. Present in an increased level in yabG mutant spores.