ATP-driven self-assembly of a morphogenetic protein in Bacillus subtilis.

A hallmark of morphogenesis is the orchestrated assembly of complex, supramolecular structures. One such structure is the proteineous coat that surrounds spores of the bacterium Bacillus subtilis. The coat is a multilayered shell that is composed of more than 50 proteins. These proteins assemble around a basement layer composed of the morphogenetic protein SpoIVA. We show that SpoIVA harbors a Walker A box that is required for the proper deployment of the protein to the surface of the developing spore and proper assembly of the entire coat. We further show that purified SpoIVA both binds and hydrolyzes ATP and that the protein self-assembles into cable-like structures in a manner that depends on ATP hydrolysis. Self-assembly driven by ATP is an unusual mechanism for the construction of a large cellular structure.