DNA Translocase Spoiiie (spoIIIE) Bacillus Subtilis Recombinant Protein

Function: Plays an essential role during sporulation. Required for the translocation of the chromosomal DNA from mother cell into the forespore during polar septation, for the final steps of compartimentalization in the presence of trapped DNA, and for the final steps of engulfment. The N-terminus mediates localization to the division septum and is required for both septal membrane fusion and engulfment membrane fusion. May form DNA-conducting channels across the two lipid bilayers of the septum after cell division. The C-terminus functions as a DNA motor that exports DNA in an ATP-dependent manner from mother cell into the forespore. DNA-binding proteins are stripped off the chromosome during translocation, which may play a key role in reprogramming developmental gene expression in the forespore. The two arms of the chromosome are simultaneously pumped into the forespore, which suggests that the septum contains at least two channels, one for each arm. Required for separation of chromosome termini. Also required for optimal chromosome partitioning in vegetative cells, by actively moving chromosomal DNA trapped within the division septum into the daughter cells. Ref.6 Ref.7 Ref.8 Ref.9 Ref.10 Ref.11 Ref.12 Ref.14 Ref.15 Ref.16 Ref.18 Ref.19 Ref.20

Subunit structure: Homohexamer. Forms a ring that surrounds DNA. Assembles into complexes that could contain two hexamers. Ref.11

Subcellular location: Cell membrane; Multi-pass membrane protein. Note: Localizes to the middle of the sporulation septum, then moves to the forespore pole before the completion of engulfment. Delocalizes after membrane fusion is complete. During sporulation, is exclusively assembled on the mother-cell side of the septum. During vegetative growth, assembles at the division septum when DNA is entrapped in the membranes. Ref.6 Ref.10 Ref.16 Ref.18 Ref.19

Domain: Consists of an N-terminal domain, followed by a linker domain, and a C-terminal domain, which forms the translocation motor involved in chromosome segregation. The C-terminal domain can be further subdivided into alpha, beta and gamma subdomains. Specific interactions between the gamma subdomain and specific SpoIIIE recognition sequences (SRS) regulate the compartment-specific activation of a mother-cell SpoIIIE complex. Interactions with nonpermissive SRS in the forespore lead to inactivation of the complex. Ref.13 Ref.16

Disruption phenotype: Cells lacking this gene show a chromosome translocation defect and aberrant compartimentalization of both sigma-F and sigma-E, and fail to complete membrane fusion at the end of engulfment. Ref.6

Sequence similarities: Belongs to the FtsK/SpoIIIE/SftA family.Contains 1 FtsK domain.

Sequence caution: The sequence CAB13553.2 differs from that shown. Reason: Erroneous initiation. Translation N-terminally shortened.