Control of Development by Altered Localization of a Transcription Factor in B. subtilis

Abstract

In B. subtilis, the chromosome partitioning proteins Soj (ParA) and Spo0J (ParB) regulate the initiation of sporulation. Soj is a negative regulator of sporulation gene expression, and Spo0J antagonizes Soj function. Using fusions of Soj to green fluorescent protein, we found that Soj localized near the cell poles and upon entry into stationary phase oscillated from pole to pole. In the absence of Spo0J, Soj was associated predominantly with DNA. By in vivo cross-linking and immunoprecipitation, we found that Soj physically associates with developmentally regulated promoters, and this association increased in the absence of Spo0J. These results show that Soj switches localization and function depending on the chromosome partitioning protein Spo0J. We further show that mutations in the Soj ATPase domain disrupt localization and function and render Soj insensitive to regulation by Spo0J.

Control of Sporulation Gene Expression in Bacillus subtilis by the Chromosome Partitioning Proteins Soj (ParA) and Spo0J (ParB)

“…Soj associates with several sporulation promoters in vivo (36) and at least one of these promoters in vitro (4). We tested for the association of Soj with the spo0A promoter region in vivo by using a cross-linking-immunoprecipitation assay (see Materials and Methods).…”

“…Two hours after the end of exponential growth in 2ϫSG, 10-ml samples of culture were taken for analysis. Generally, cross-linking and sample preparations were performed as described earlier (22,36) and are based on previously published chromatin immunoprecipitation assays (8,39,40). Samples were treated with sodium phosphate (10 mM final concentration) and formaldehyde (1% final concentration) for 3 min at room temperature.…”

“…Histidine-tagged Soj inhibits transcription from the spoIIG promoter in vitro (4). In addition, formaldehyde crosslinking has shown that Soj associates with several Spo0AϳP-dependent promoters in vivo, including spoIIA, spoIIE, and spoIIG, and that this association correlates with decreased gene expression (36).…”

“…Chromosome-encoded family members have also been identified, several of which function in chromosome partitioning (14,22,26). Members of the ParA-SopA families can act as transcriptional repressors and are themselves often regulated by members of the ParB-SopB family (7,9,24,27,36).Spo0J is required both for accurate chromosome partitioning and for sporulation (14). Spo0J binds to a series of sites (parS sites) in the origin-proximal 20% of the chromosome (22), clustering them into a large focus (10,21,23).…”

“…Chromosome-encoded family members have also been identified, several of which function in chromosome partitioning (14,22,26). Members of the ParA-SopA families can act as transcriptional repressors and are themselves often regulated by members of the ParB-SopB family (7,9,24,27,36).…”