The gerB region of the Bacillus subtilis 168 chromosome encodes a homologue of the gerA spore germination operon

Abstract

Spores of gerB spore germination mutants of Bacillus subtilis 168 are defective in response to the germinative mixture of L-asparagine, glucose, fructose and potassium ions (AGFK), but are normal in the L-alanine (ALA) triggered germination response. A 3. clone of 15 kbp carrying the gerB region has been identified. Sequencing of the gerB region of the clone revealed a cluster of three ORFs encoding putative proteins of 53.3,41.3 and 42-4 kDa (GerBA, GerBB and GerBC, respectively). The first two of these proteins have substantial hydrophobic regions and the third i s a possible lipoprotein. A t least two, and probably all three products are required for normal germination in AGFK. The three proteins form a set of homologues of the products of the gerA operon, mutations in which cause a defect in the ALA germination pathway, but cause no defect in AGFK. The GerB proteins show 42%, 31 O/ O and 3 5 % identity a t the amino-acid level to the corresponding GerA proteins, and the homologues occur in the same order in both operons.

Genome-wide analysis of temporally regulated and compartment-specific gene expression in sporulating cells of Bacillus subtilis

“…The evidence suggests that the main period of spoIIIG transcription follows the activation of s G after the completion of engulfment (Errington, 2003;Hilbert & Piggot, 2004;see above). s G then drives expression of the spoVA operon, required for the uptake of dipicolinic acid from the mother cell into the prespore (Tovar-Rojo et al, 2002); spoVT, a modulator of s G -dependent gene expression (Bagyan et al, 1996); bofC and spoIVB, required for signalling pro-s K activation in the mother cell (Cutting et al, 1991a;Gomez & Cutting, 1996Wakeley et al, 2000); the gerA, gerB and gerK operons, required for efficient spore germination (Corfe et al, 1994;Feavers et al, 1990; this work, Supplementary Table S3); pdaA, involved in the formation of muramic d-lactam in the spore cortex peptidoglycan, and indirectly in efficient spore germination (Fukushima et al, 2002); and sleB, encoding a cortex lytic enzyme activated during germination (Boland et al, 2000). An important function of the s G regulon lies in spore protection.…”

Functional Consequences of Amino Acid Substitutions to GerVB, a Component of the Bacillus megaterium Spore Germinant Receptor

“…Indirect genetic evidence for physical interaction between the respective A, B, and C proteins that comprise the receptor (13) has been complemented recently by yeast two-hybrid experiments (34), which, in addition to providing evidence for the interaction between receptor subunits, also suggest that some receptor proteins interact with SpoVA proteins thought to be involved in the release of calcium dipicolinate during germination. Similarly, while some germinant receptors can function independently to trigger the spore germination response, for example, the GerA-mediated L-alanine response in Bacillus subtilis, most germinant receptors appear to work in concert to initiate germination, either in response to single germinants (e.g., the GerQ and GerI response to inosine in Bacillus cereus [4]) or to mixtures of germinants (e.g., the GerB-and GerK-mediated response to AGFK in B. subtilis [9,15]). Again, genetic evidence employing mutant B. subtilis constructs has been presented suggesting that different receptors can physically interact (3,5).…”

Nucleotide sequence and gene organization of the gerK spore germination locus of Bacillus subtilis 168.

“…Gene organization and the nucleotide sequence Sequencing of the 4-kb insert of the cb 105 phage, GK2, revealed three ORFs including the previously sequenced second ORF (formerly named simply "gerK," 5) encoding a putative lipoprotein precursor homologous with the products of the gerAC (24) and gerBC (1).…”

“…Further-more, higher homology was found with the product of gerBC, the third gene of gerB operon (1) which is another locus required for AGFK-induced germination. The gerB operon is suggested to encode the receptor molecules for ASN and is a closely related homologue of the gerA operon (1).…”