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Mendelian and uniparental alterations in erythromycin binding by plastid ribosomes
Abstract:
Erythromycin binds specifically to the 52S subunit of the chloroplast ribosome of Chlamydomonas reinhardi. A number of erythromycin-resistant mutants whose ribosomes have lost their affinity for the antibiotic have been isolated, but the sedimentation properties of their ribosomes are indistinguishable from those of the wild-type strain. These mutants represent at least three genetic loci. Two of them show Mendelian inheritance, and one of them is inherited in a uniparental manner.
Insights
Erythromycin resistance in Chlamydomonas reinhardi chloroplast ribosomes was studied. Resistant mutants show altered antibiotic binding but normal ribosome structure, with varied genetic inheritance patterns.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Erythromycin is an antibiotic that targets bacterial and organelle ribosomes.
- Chloroplast ribosomes in Chlamydomonas reinhardi are responsible for protein synthesis within the chloroplast.
Purpose of the Study:
- To investigate the genetic basis of erythromycin resistance in Chlamydomonas reinhardi chloroplast ribosomes.
- To characterize mutants with altered erythromycin binding affinity to chloroplast ribosomes.
Main Methods:
- Isolation and characterization of erythromycin-resistant Chlamydomonas reinhardi mutants.
- Analysis of ribosome sedimentation properties.
- Genetic analysis to determine inheritance patterns.
Main Results:
- Erythromycin specifically binds to the 52S subunit of Chlamydomonas reinhardi chloroplast ribosomes.
- Isolated mutants exhibited resistance due to reduced ribosome affinity for erythromycin.
- Ribosome sedimentation properties remained unchanged in resistant mutants compared to wild-type.
- Mutants mapped to at least three distinct genetic loci.
- Two loci displayed Mendelian inheritance, while one showed uniparental inheritance.
Conclusions:
- Erythromycin resistance in Chlamydomonas reinhardi chloroplasts is mediated by alterations in ribosome-antibiotic interaction.
- Genetic analysis reveals complex inheritance patterns for organelle antibiotic resistance.
- The 52S ribosomal subunit is the primary target for erythromycin in Chlamydomonas reinhardi chloroplasts.