The codon table for the canonical genetic code can be rearranged in such a waythat the code is divided into four quarters and two halves according to the vari-ability of their GC and purine contents, respectively. For prokaryotic genomes,when the genomic GC content increases, their amino acid contents tend to berestricted to the GC-rich quarter and the purine-content insensitive half, whereall codons are fourfold degenerate and relatively mutation-tolerant. Conversely,when the genomic GC content decreases, most of the codons retract to the AU-rich quarter and the purine-content sensitive half; most of the codons not onlyremain encoding physicochemically diversified amino acids but also vary whentransversion (between purine and pyrimidine) happens. Amino acids with sixfold-degenerate codons are distributed into all four quarters and across the two halves;their fourfold-degenerate codons are all partitioned into the purine-insensitive halfin favorite of robustness against mutations. The features manifested in the re-arranged codon table explain most of the intrinsic relationship between proteincoding sequences (the informational content) and amino acid compositions (thefunctional content). The renovated codon table is useful in predicting abundantamino acids and positioning the amino acids with related or distinct physicochem-ical properties.Key words: genetic code, codon, GC content, purine contentThe universal table for the canonical genetic code hasnot been changed much since it was discovered andtabulated (
['Jun Yu']
A Content-Centric Organization of the Genetic Code