The Bacillus subtilis spo0J gene: evidence for involvement in catabolite repression of sporulation

Abstract

Previous observations concerning the ability of the Bacillus subtilis bacteriophages SP10 and PMB12 to suppress mutations in spoOJ and to make wild-type sporulation catabolite resistant suggested that spoOJ had a role in catabolite repression of sporulation. This suggestion was supported in the present report by the ability of the catabolite-resistant sporulation mutation crsF4 to suppress a Tn917 insertion mutation of the B. subtilis spoOJ locus (spoOJ::Tn917fQHU261) in medium without glucose. Although crsF4 and SP10 made wild-type B. subtilis sporulation catabolite resistant, neither crsF4 nor SP10 caused a mutant with spoOJ::Tn917Q1HU261 to sporulate in medium with glucose. Sequencing the spoOJ locus revealed an open reading frame that was 179 codons in length. Disruption of the open reading frame resulted in a sporulation-negative (Spo-) phenotype that was similar to those of other spoOJ mutations. Analysis of the deduced amino acid sequence of the spoOJ locus indicated that the spoOJ gene product contains an ot-helix-turn-a-helix unit similar to the motif found in Cro-like DNA-binding proteins.Bacillus subtilis sporulation is a model system that is used to study procaryotic gene expression and cellular differentiation as responses to environmental stimuli. Sporulation is subject to catabolite repression; i.e., the presence of glucose or other readily metabolized carbon sources inhibits sporulation by wild-type cells (33). Initiation of sporulation is controlled by at least seven genes, spoOA, spoOB, spoOE, spoOF, spoOH, spoOJ, and spoOK (23). Glucose represses transcription of spoOA and spoOF (3, 43). However, it is not known how availability of nutrients regulates initiation of sporulation. Several spoO genes have been sequenced (5,9,14,15,30,41). It is evident from this work that the spoOH gene codes for a sigma subunit of RNA polymerase and that some spoO genes are responsible for sensing environmental conditions. The spoOA and spoOF gene products are homologous to the effector molecules of the two-component response regulator systems that have been described for a variety of bacteria (15,41 PMB12 and SP10 are also able to suppress the Spo-and oligosporogenic phenotypes of various spoOJ mutations (6,20,34). As a result, both PMB12-infected and SP10-infected spoOJ mutants sporulate at a significantly higher frequency than uninfected spoOJ mutants. The observations that PMB12-and SP10-infected bacteria display catabolite-resistant sporulation and that these bacteriophages suppress spoOJ mutations suggest that spoOJ has a role in catabolite repression of sporulation.The spoOJ locus was originally thought to be represented by two mutations, spoOJ87 and spoOJ93 (17). However, spoIIA and spaIID are expressed in a strain with spoOJ87, whereas spoOJ93 blocks expression of these genes (7, 13). The wild-type alleles of both mutations have been cloned into bacteriophage 0105 vectors (10,12 spoOJ93 (45).The data presented in this report provide additional evidence for the involvement of spoOJ in catabolite repressi...

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

“…Spo0A obtains phosphate from a set of proteins called the phosphorelay (2). A balance of kinases and phosphatases regulates phosphate input into the phosphorelay and the phosphorylation state of Spo0A (3,(30)(31)(32).Two proteins involved in chromosome partitioning, Soj and Spo0J, also regulate the initiation of sporulation, perhaps in response to chromosome structure or partitioning (4,14,28). Soj and Spo0J are members of the ParA-SopA and ParB-SopB protein families, respectively.…”

“…Defects in spo0J perturb chromosome partitioning. Cultures of spo0J null mutant cells produce approximately 1% anucleate cells, a frequency approximately 20-to 100-fold greater than that of wildtype cells (14).A null mutation in spo0J also causes an approximately 300-fold defect in sporulation relative to wild-type cells (14,28,34). spo0J null mutants are blocked early in sporulation (stage 0) and have decreased expression of at least three Spo0AϳP-activated, sporulation genes (14, 28).…”

“…Two proteins involved in chromosome partitioning, Soj and Spo0J, also regulate the initiation of sporulation, perhaps in response to chromosome structure or partitioning (4,14,28). Soj and Spo0J are members of the ParA-SopA and ParB-SopB protein families, respectively.…”

“…A null mutation in spo0J also causes an approximately 300-fold defect in sporulation relative to wild-type cells (14,28,34). spo0J null mutants are blocked early in sporulation (stage 0) and have decreased expression of at least three Spo0AϳP-activated, sporulation genes (14,28).…”

“…spo0J null mutants are blocked early in sporulation (stage 0) and have decreased expression of at least three Spo0AϳP-activated, sporulation genes (14,28). The defects in sporulation and gene expression caused by ⌬spo0J are completely suppressed by the deletion of soj.…”