Non-AUG translation initiation of mRNA encoding acidic ribosomal P2A protein in Candida albicans

Area of Science:

• Molecular Biology
• Yeast Genetics
• Protein Biochemistry

Background:

• The 60S ribosomal subunit contains acidic P-proteins forming the stalk structure, essential for polypeptide synthesis elongation.
• Acidic ribosomal P-proteins play a critical role in protein translation.
• Candida albicans is a significant human opportunistic pathogen.

Purpose of the Study:

• To isolate and characterize the CARP2A gene and its P2A protein product in Candida albicans.
• To investigate the genetic and molecular features of a specific acidic ribosomal protein in a pathogenic yeast.
• To identify novel regulatory elements in yeast gene expression.

Main Methods:

• Gene isolation and characterization of CARP2A in Candida albicans.
• Bioinformatic analysis of the CARP2A gene sequence and P2A protein.
• Determination of gene copy number and transcriptional activity.
• Analysis of the start codon in the CARP2A mRNA transcript.

Main Results:

• The CARP2A gene is intron-less, single-copy, and transcriptionally active in Candida albicans.
• The P2A protein is calculated to have a molecular mass of 10.85 kDa and an isoelectric point of 3.7.
• The CARP2A gene transcript utilizes a GUG start codon, a rare occurrence in eukaryotes and previously unreported in yeast.
• This study reports the first instance of a naturally occurring non-AUG start codon on mRNA in yeast.

Conclusions:

• The CARP2A gene and P2A protein are well-characterized components of the Candida albicans ribosome.
• The identification of a GUG start codon in CARP2A mRNA provides new insights into translational initiation mechanisms in yeast.
• This finding expands the understanding of eukaryotic gene expression and translational control in pathogenic fungi.