THE BACILLUS-SUBTILIS DIVISION PROTEIN DIVLC IS A HIGHLY ABUNDANT MEMBRANE-BOUND PROTEIN THAT LOCALIZES TO THE DIVISION SITE

The Bacillus subtilis divIC gene is involved in the initiation of cell division. It encodes a 14.7 kDa protein, with a potential transmembra ne region near the N-terminus. In this paper, we show that DivIC is as sociated with the cell membrane and, in conjunction with previously pu blished sequence data, conclude that it is oriented such that its smal l N-terminus is within the cytoplasm and its larger C-terminus is exte rnal to the cytoplasm, DivIC is shown to be a highly abundant division protein, present at approximately 50 000 molecules per cell. Using im munofluorescence microscopy, DivIC was seen to localize at the divisio n site of rapidly dividing cells between well-segregated nucleoids. Va rious DivIC immunostaining patterns were observed, and these correlate d with different cell lengths, suggesting that the DivIC localization takes on various forms during the cell cycle. The DivIC immunolocaliza tion patterns are very similar to those of another membrane-bound B. s ubtilis division protein, DivIB.