PRDM9: The most exciting Gene in the Genome?
PRDM9: the word alone may not strike as noteworthy, but don’t let the alphanumeric code deceive you. It might just prove to be one of the most fascinating and peculiar gene within our genome; posing vast implications for our understanding of life and evolution.
Students have for years memorised, recounted, and rewritten of random recombination, or shuffling of genes within sex cells; a process vital to producing the variation we see in organisms today. However when Professor Gilean McVean’s team at the Wellcome Trust centre for Human Genetics sequenced at which points along a chromosome such shuffling occurs, the results were surprising. Speaking at the Royal Society he stated “until recently we knew very little where it happened…. and why it happened” but it now appears “most recombination is clustered in to 5-10 %of genome in short windows of about 1000 bases”. Such reordering within hotspots on chromosomes is neither random nor even. So what causes it?
Protein PRDM9 (coded by gene of same name) naturally. It appears all mammals have different PRDM9 consequently binding to different hotspots, determining where and how their genome is reorganised. For instance humans and chimpanzees share on average 99% of DNA, with many proteins only being different by one amino acid. But in the case of PRDM9 the sequences are utterly different in both, with the PRDM9 gene perhaps being the most diverged between the two. As human beings “we think of being almost identical” to chimpanzees “at the cellular level, in terms of molecular processes” but this indicates “something has fundamentally switched”. The gene itself is changing at orders of magnitude greater than any other and may well have played part in early human chimpanzee separation from common ancestor. Studies in mice on the verge of becoming two separate species identify different PRDM9.Whilst slight variations in the PRDM9 within us also dictate what kind of mutations and disorders arise when it identifies a wrong hotspot, consequently causing wrong rearrangement.
PRDM9’s discovery highlights “just how bizarre the human genome” can be when you begin to unravel it and how processes such as recombination when explored in detail can have truly“unexpected turns and consequences”.Tagged in: genes, PRDM9, science
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