Figure 6
Calculation of the number of novel proteins that can be produced by ambiguous decoding of low CAI mRNAs. (a) Novel proteins arising from ambiguous decoding of mRNAs encoded by genes with low codon adaptation index (CAI) value in the different physiologic conditions indicated. The RAD17 gene, containing three CUG codons, was used as an example of a gene with a low CAI, because its CAI value falls within the range of values exhibited by the 10% of genes with lowest CAI value in Candida albicans (CAIRAD17 = 0.448). This set of genes produce approximately 5,000 protein molecules in vivo in yeast [24]. (b) Total number of different proteins that can be generated from ambiguous CUG decoding. The probability of different proteins that arise from genes containing CUGs, caused by serine or leucine insertion at CUG positions, was calculated as described in the Materials and methods section. In this case, of the 5,000 Ra17p molecules synthesized, 4,569 are wild-type and 429 are novel molecules (8.6%). The data unequivocally show that C. albicans proteins are quasi-species [43] and that its proteome has a statistical nature.