Mapping of the genes for Bacillus subtilis ribosomal proteins S9, S11, and BL27 by means of antibiotic resistant mutants

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.

Gene for the alpha subunit of Bacillus subtilis RNA polymerase maps in the ribosomal protein gene cluster

We isolated the gene encoding the alpha subunit of Bacillus subtilis RNA polymerase from a lambda gt11 expression vector library by using anti-alpha antibody as a probe. Four unique clones were isolated, one carrying a lacZ-alpha gene fusion and three carrying the entire alpha coding region together with additional sequences upstream. The identity of the cloned alpha gene was confirmed by the size and immunological reactivity of its product expressed in Escherichia coli. Further, a partial DNA sequence found the predicted NH2 terminus of alpha homologous with E. coli alpha. By plasmid integration and PBS1 transduction, we mapped alpha near rpsE and within the major ribosomal protein gene cluster on the B. subtilis chromosome. Additional DNA sequencing identified rpsM (encoding S13) and rpsK (encoding S11) upstream of alpha, followed by a 180-base-pair intercistronic region that may contain two alpha promoters. Although the organization of the alpha region resembles that of the alpha operon of E. coli, the putative promoters and absence of rpsD (encoding S4) immediately preceding the B. subtilis alpha gene suggest a different regulation.

Mapping of the genes for Bacillus subtilis ribosomal proteins S6 and S16: comparison of the chromosomal distribution of ribosomal protein genes in this bacterium with the distribution in Escherichia coli

Using mutants of Bacillus subtilis with alterations in the small subunit ribosomal proteins S6 and S16, the corresponding genes were mapped. rpsF was located between purA and cysA, close to the origin of replication. rpsP was located near pyrD, at about 135 degrees on the linkage map. The distribution on the chromosome of the ribosomal protein gene loci so far identified in B. subtilis was compared with the distribution of the genes for the same proteins in Escherichia coli. Considered in terms of relative distance from the origin and terminus of chromosomal replication, the order was the same in both species with the sole exception of protein S6.

A pair of Bacillus subtilis ribosomal protein genes mapping outside the principal ribosomal protein cluster

Before now, the only ribosomal protein gene loci to be identified in Bacillus subtilis map within the principal ribosomal protein gene cluster at about 10 degrees on the linkage map. Using mutants with alterations in large subunit ribosomal proteins L20 or L24, I mapped the corresponding genes near leuA at approximately 240 degrees. The data were fully consistent with the fact that the genes for the two proteins were close together but not near any other ribosomal protein genes, as is also the case with the genes for the corresponding proteins of Escherichia coli.

Arrangement of loci within the principal cluster of ribosomal protein genes of Bacillus subtilis

Strains of Bacillus subtilis harboring mutations causing altered migration of one or more of ten ribosomal proteins were used to map the corresponding gene loci. The loci of the genes for proteins BL1, BL5, BL9, and BL11 mapped between cysA and rpoB. The locus of the gene for protein S7 was very close to the gene for protein S12 (rpsL). Those for proteins S8, BL6, BL7, BL8, and BL23 were between rpsL and rpsE (the gene for protein S5). Where the order of loci could be deduced, it was strikingly similar to that of Escherichia coli.