A Genomic Survey of Angiotensin-Converting Enzymes Provides Novel Insights into Their Molecular Evolution in Vertebrates

Angiotensin-converting enzymes, ACE and ACE2, are two main elements in the renin-angiotensin system, with a crucial role in the regulation of blood pressure in vertebrates. Previous studies paid much attention to their physiological functions in model organisms, whereas the studies on other animals and related evolution have been sparse. Our present study performed a comprehensive genomic investigation on ace and ace2 genes in vertebrates. We successfully extracted the nucleotide sequences of ace and ace2 genes from high-quality genome assemblies of 36 representative vertebrates. After construction of their evolutionary tree, we observed that most of the phylogenetic positions are consistent with the species tree; however, certain differences appear in coelacanths and frogs, which may suggest a very slow evolutionary rate in the initial evolution of ace and ace2 in vertebrates. We further compared evolutionary rates within the entire sequences of ace and ace2, and determined that ace2 evolved slightly faster than ace. Meanwhile, we counted that the exon numbers of ace and ace2 in vertebrates are usually 25 and 18 respectively, while certain species may occur exon fusion or disruption to decrease or increase their exon numbers. Interestingly, we found three homologous regions between ace and ace2, suggesting existence of gene duplication during their evolutionary process. In summary, this report provides novel insights into vertebrate ace and ace2 genes through a series of genomic and molecular comparisons.