Translational attenuation of ermC: a deletion analysis

Area of Science:

• Molecular Biology
• Microbiology
• Genetics

Background:

• The ermC gene confers resistance to macrolide-lincosamide-streptogramin B antibiotics.
• Its product, an rRNA methylase, is translationally regulated via a proposed translational attenuation model.
• This model involves erythromycin-induced ribosome stalling affecting ermC mRNA conformation.

Purpose of the Study:

• To experimentally test the proposed translational attenuation model for ermC gene regulation.
• To investigate the role of specific regulatory regions within the ermC leader sequence.
• To refine and extend the understanding of ermC gene expression control.

Main Methods:

• Construction and analysis of a series of ermC deletion mutants.
• Fusion of ermC to an upstream promoter to control transcription.
• DNA sequencing to determine deletion endpoints within the regulatory region.

Main Results:

• Deletion mutants exhibited varied ermC expression: high-level inducible, high-level noninducible, and low-level noninducible.
• Observed expression patterns confirmed predictions of the translational attenuation model regarding leader region sequences.
• Specific deletions correlated with altered translational control and methylase expression levels.

Conclusions:

• The translational attenuation model is supported by experimental evidence from deletion mutants.
• Refined model incorporates direct translational activation and kinetic trapping for basal methylase synthesis.
• Understanding ermC regulation provides insights into antibiotic resistance mechanisms.