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Morphology and patterns of protein synthesis during sporulation of Bacillus subtilis Eryr spo(Ts) mutants
Abstract:
Erythromycin-resistant (Eryr) mutants of Bacillus subtilis 168 fail to sporulate at high temperature (47 degrees C) but sporulate normally at 30 to 35 degrees C. They also fail to sporulate at any temperature in the presence of 2.5 micrograms of erythromycin per ml. Neither of these nonpermissive conditions appears to affect vegetative growth, and the periods of sensitivity to both conditions extend from 40 to 90% of the sporulation period. At 47 degrees C, net incorporation of methionine and phenylalanine in postexponential Eryr and 168 cells was similar, and fractionation of the labeled products by polyacrylamide gel electrophoresis gave patterns in which many of the bands produced by mutant and parental cells coincided. However, distinct differences were seen, and since no spore-specific morphogenesis occurred in the Eryr cells at 47 degrees C, a selective defect in spore gene expression was inferred. At 35 degrees C plus erythromycin, spore morphogenesis proceeded normally until forespores were produced and then ceased, coincident with a marked increase in sensitivity of total protein synthesis to erythromycin. The effects seem to be nonspecific, therefore, and may indicate a change in cell permeability or ribosomal sensitivity to erythromycin.
Insights
Erythromycin-resistant Bacillus subtilis mutants exhibit temperature-sensitive sporulation defects. These mutants also fail to sporulate in the presence of erythromycin, suggesting potential changes in cell permeability or ribosomal sensitivity.
Area of Science:
- Microbiology
- Bacterial Genetics
- Cellular Biology
Background:
- Bacillus subtilis is a model organism for studying bacterial sporulation.
- Erythromycin resistance mutations can affect various cellular processes.
- Sporulation is a complex developmental process in bacteria.
Purpose of the Study:
- To investigate the sporulation defects in erythromycin-resistant Bacillus subtilis mutants.
- To determine the effects of high temperature and erythromycin on mutant sporulation.
- To elucidate the underlying molecular mechanisms of these defects.
Main Methods:
- Generating and characterizing erythromycin-resistant Bacillus subtilis mutants.
- Assessing sporulation efficiency at different temperatures and erythromycin concentrations.
- Analyzing protein synthesis and gene expression using radiolabeling and gel electrophoresis.
- Observing spore morphogenesis through microscopy.
Main Results:
- Erythromycin-resistant mutants failed to sporulate at 47°C but sporulated normally at 30-35°C.
- Mutants also failed to sporulate in the presence of erythromycin, with sensitivity extending throughout most of the sporulation period.
- Protein synthesis analysis revealed distinct differences between mutant and wild-type cells at 47°C, suggesting a defect in spore gene expression.
- At 35°C with erythromycin, spore morphogenesis halted after forespore formation, coinciding with increased sensitivity of protein synthesis to erythromycin.
Conclusions:
- Erythromycin resistance in Bacillus subtilis can lead to temperature-sensitive sporulation defects.
- The observed sporulation failures suggest a selective defect in spore gene expression at high temperatures.
- Erythromycin-induced sporulation arrest may be a non-specific effect related to altered cell permeability or ribosomal sensitivity.