Speeding with control: codon usage, tRNAs, and ribosomes.

Codon usage and tRNA abundance are critical parameters for gene synthesis. However, the forces determining codon usage bias within genomes and between organisms, as well as the functional roles of biased codon compositions, remain poorly understood. Similarly, the composition and dynamics of mature tRNA populations in cells in terms of isoacceptor abundances, and the prevalence and function of base modifications are not well understood. As we begin to decipher some of the rules that govern codon usage and tRNA abundances, it is becoming clear that these parameters are a way to not only increase gene expression, but also regulate the speed of ribosomal translation, the efficiency of protein folding, and the coordinated expression of functionally related gene families. Here, we discuss the importance of codon-anticodon interactions in translation regulation and highlight the contribution of non-random codon distributions and post-transcriptional base modifications to this regulation.