Revertants of a streptomycin-resistant, oligosporogenous mutant of Bacillus subtilis

Bacillus subtilis mutants with alterations in ribosomal protein S4

Two mutants with different alterations in the electrophoretic mobility of ribosomal protein S4 were isolated as spore-plus revertants of a streptomycin-resistant, spore-minus strain of Bacillus subtilis. The mutations causing the S4 alterations, designated rpsD1 and rpsD2, were located between the argGH and aroG genes, at 263 degrees on the B. subtilis chromosome, distant from the major ribosomal protein gene cluster at 12 degrees. The mutant rpsD alleles were isolated by hybridization using a wild-type rpsD probe, and their DNA sequences were determined. The two mutants contained alterations at the same position within the S4-coding sequence, in a region containing a 12-bp tandem duplication; the rpsD1 allele corresponded to an additional copy of this repeated segment, resulting in the insertion of four amino acids, whereas the rpsD2 allele corresponded to deletion of one copy of this segment, resulting in the loss of four amino acids. The effects of these mutations, alone and in combination with streptomycin resistance mutations, on growth, sporulation, and streptomycin resistance were analyzed.

Genetic mapping of a mutation causing an alteration in Bacillus subtilis ribosomal protein S4

A mutation causing an alteration in Bacillus subtilis ribosomal protein S4 was mapped by transformation and PBS-1 transduction to a site between aroG and argA, a region of the B. subtilis chromosome not previously demonstrated to contain ribosomal protein genes. The S4 mutation conferred a spore-plus phenotype in a streptomycin-resistant, spore-minus genetic background. The altered protein was detectable by polyacrylamide gel electrophoresis of ribosomal proteins of recombinants scored for the spore-plus phenotype in genetic crosses.

Genetic analysis of a streptomycin-resistant oligosporogenous Bacillus subtilis mutant

Strain SRB15T+, a streptomycin-resistant, oligosporogenous mutant of Bacillus subtilis, contains two mutations, fun and strR. These mutations were mapped by PBS-1 mediated transduction and by transformation to two different sites in the cysA-linked region of the B. subtilis chromosome. The fun mutation mapped very close to rpsLl, a classic strA mutation, whereas strR mapped to a site distal to rpsE. The effects of these mutations on growth, sporulation, and streptomycin resistance in vivo and in vitro were determined. The fun mutation gave a different phenotype than did the rpsLl mutation and caused altered migration of a ribosomal protein which was identified as S12, the protein encoded by rpsL. It therefore appears that fun is an allele of the rpsL gene.