Virus-fighting protein in primates that initiates swift, integrated and aggressive mechanism may have sped up evolution, a new study has found. The findings bring up doubts regarding the use of more common mutation process to ascertain when two species differentiated and the extent of impact of these mutation and related enzymes in primate evolution.
Evolution has always been considered gradual, a slow process of accumulating individual mutations in each rising generation. However, in a new study, scientists who analyzed hominid genomes discovered thousands of assembled mutations probably due to the coordinated action of so-called APOBEC enzymes, known to have anti-viral immunity properties.
A Look At APOBEC
The APOBEC family has recently been recognized to initiate mutations in several kinds of cancers. The enzymes are said particularly to alter the DNA during the process.
An interesting finding is that the APOBEC family has significantly increased in copy number among primates. The development is said to be a response to the rise of primate-specific viruses - the pathogens aims to inactivate.
Testing Hypothesis
The researchers hypothesized that a particular APOBEC protein called APOBEC3 has the ability to start unique mutation clusters in sex cells (eggs and sperm). Such idea may signify a key aspect of primate evolution.
The team studied genome sequence from present-day and archaic humans, and great apes. They particularly searched for mutations that possibly resulted from APOBEC3 activity.
APOBEC3 is known to recognize only one pattern of DNA and it targets only one DNA base for mutation. The team found thousands of such instances in primates and not in other vertebrates such as mice that do not have APOBEC3 genes.
Corresponding author Alon Keinan says their work is in conflict with predictions of mutation models that are based on most genetic studies such as medical and population genetics.
"It is tempting to suggest that some of the features that make us human are the result of this evolution 'fast track' option," says co-corresponding author Erez Levanon.
The study was published in the journal Genome Research on April 7.
