Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
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The Bacillus subtilis mutant cal1 carries a non-reverting mutation in ribosomal protein L17 (r-protein L17) that causes both resistance to the antibiotic chalcomycin (Calr) and temperature-sensitive sporulation (Spots). Second-site suppressor (rev) mutations that relieve the Spots phenotype have been isolated from cal1. Three suppressor mutations - rev4, rev10, rev11 - each increase the sporulation frequency of cal1 at the non-permissive temperature from 3% to 95% of the wild-type level. The cal1 rev strains remain resistant to chalcomycin and two-dimensional gel electrophoresis analysis indicates that they contain the same altered r-protein L17 as the original cal1 strain and no additional altered r-proteins. The three rev mutations have been mapped at a single locus between narA and sacA on the B. subtilis chromosome and recombination indexes for the rev mutations indicate that they are tightly linked to one another. Antibiotic resistance Spots mutations that cause temperature-sensitive sporulation have previously been isolated in RNA polymerase, in the 30S and 50S subunits of the ribosome, and in elongation factor G. The rev4, 10, and 11 suppressor mutations are non-specific in their action in that they restore significant levels of sporulation at the non-permissive temperature in all of the Spots strains that we have tested. This result suggests that Spots mutations in components of the B. subtilis transcription and translation systems share a common molecular basis for their sporulation-defective phenotypes.
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PMID:Intergenic suppressors of temperature-sensitive sporulation in Bacillus subtilis are allele non-specific. 680 27

Five hundred putative RNA polymerase mutants of Bacillus subtilis were isolated by selecting for resistance to the RNA polymerase inhibitors rifampin (Rifr), streptovaricin (Strr) or streptolydigan (Stdr). This collection was screened for mutants that were unable to sporulate at the non-permissive temperature of 46 degrees C, yet which sporulated well at 37 degrees C and had normal vegetative growth (Spots phenotype). Nearly one half of the Rifr and one quarter of the Stvr mutants were Spots, whereas none of the Stdr mutants had this phenotype. The streptovaricin resistant strain stv84 was studied in detail. The stv84 mutation maps between cysA14 and strA39 on the B. subtilis chromosome, and the Stvr and Spots phenotypes cotransform at a frequency of 100%. The Spots phenotype of stv84 could be physiologically corrected by supplementing the growth medium with inhibitors of RNA synthesis such as rifampin or azauracil, with carbohydrates such as ribose, mannose or glycerol, or with lipids such as Tween 40 or fatty acids native to Bacillus subtilis membranes. A Spots phenotype resembling that of stv84 was produced in wild type B. subtilis by adding cerulenin, an inhibitor of fatty acid biosynthesis, to the growth medium. This cerulenin-induced sporulation defect was reversed by the same treatments that correct the temperature-sensitive genetic defect of stv84. These data indicate that the Spots phenotype of strain stv84 is not due to an intrinsic inability of the mutant RNA polymerase to transcribe developmentally-specific genes at the nonpermissive temperature. Rather, the data suggest that the stv84 lesion causes a physiological imbalance which disrupts membrane structure or function in sporulating cells.
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PMID:Physiological suppression of the temperature-sensitive sporulation defect in a Bacillus subtilis RNA polymerase mutant. 680 29

The temperature-sensitive sporulation phenotype (Spots) of Bacillus subtilis RNA polymerase, ribosomal and protein synthesis elongation factor G mutations can be corrected by supplementing the growth medium with carbohydrates such as ribose or glycerol, or with synthetic lipids such as Tween 40. The data suggest that these mutations affect a single common aspect of developmental cell function. It is proposed that these lesions prevent sporulation by disturbing the regulation of sporulating cell metabolic balance.
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PMID:Physiological suppression of Bacillus subtilis conditioned sporulation phenotypes: RNA polymerase and ribosomal mutations. 680 30