Chaperonin Hsp60, as a protein found in all organisms, is of great
interest in medicine, since it is present in many tissues and can be
used both as a drug and as an object of targeted therapy. Hence, Hsp60
deserves a fundamental comparative analysis to assess its evolutionary
characteristics. It was found that the percent identity of Hsp60 amino
acid sequences both within and between phyla was not high enough to
identify Hsp60s as highly conserved proteins. In turn, their amino acid
composition remained relatively constant. At the same time, the analysis
of the nucleotide sequences showed that GC content in the Hsp60 genes
was comparable to or greater than the genomic values, which may indicate
a high resistance to mutations due to tight control of the nucleotide
composition by DNA repair systems. Natural selection plays a dominant
role in the evolution of Hsp60 genes. The degree of mutational pressure
affecting the Hsp60 genes is quite low, and its direction does not
depend on taxonomy. Interestingly, for the Hsp60 genes from Chordata,
Arthropoda, and Proteobacteria the exact direction of mutational
pressure could not be determined. However, upon further division into
classes, it was found that the direction of the mutational pressure for
Hsp60 genes from Fish differs from that for other chordates. The
direction of the mutational pressure affects the synonymous codon usage
bias. The number of high and low represented codons increases with
increasing GC content, which can improve codon usage.