Analysis of Codon Usage Pattern and Predicted Gene Expression in Neurospora Crassa: A Novel in Silico Approach

The codon usage pattern of genes has a key role in the gene expression and adaptive evolution of an organism. It is very significant in understanding the role of complex genomic structure in defining cell fates and regulating diverse biological functions. In this paper, we discussed that the codon usage index (CAI(g)) based on all protein-coding genes is a promising alternative to the Codon Adaptation Index (CAI). CAI(g) which measures the extent that a gene uses a subset of preferred codons relies exclusively on sequence features and is used as a good indicator of the strength of codon bias. A critical analysis of predicted highly expressed (PHE) genes in Neurospora crassa has been performed using codon usage index (CAI(g)) as a numerical estimator of gene expression level. Analyzing compositional properties and codon usage pattern of genes in Neurospora crassa, our study indicates that codon composition plays an important role in the regulation of gene expression. We found a systematic strong correlation between CAI(g) and CBI (codon bias index) or other expression-measures. Here, we show that codon usage index CAI(g) correlates well with both protein and mRNA levels; suggesting that codon usage is an important determinant of gene expression. Our study highlights the relationship between gene expression and compositional signature in relation to codon usage bias in Neurospora crassa and sets the ground for future investigation in eukaryotic biology.