Enzyme SPRK1 makes way for the first step — folding and packaging the sperm so that it fits in the egg
A person’s genome is inherited from the parents — during fertilisation, half of the father’s genome is mixed with half of the mother’s.
A sperm carries half as much genetic material as a regular cell and needs to be folded and packaged in a way that it fits in the egg. While the information was well-known, what led the first step in the process wasn’t.
It is the enzyme SPRK1 that makes way for this first step — by reorganising paternal genome during the first moments of fertilisation. The study, published in journal Cell, was carried out by researchers at University of California San Diego School of Medicine discovered.
The enzyme does it in a matter of few hours, according to scientists.
According to the study, the paternal genome undergoes an exchange of proteins histone with protamine for compaction into sperm. Upon fertilisation, this process is reversed, which is how parental genome is reprogrammed and subsequently activated. SRPK-1 initiates this process.
According to Xiang-Dong Fu, co-author and professor in the Department of Cellular and Molecular Medicine, San Diego School of Medicine, the discovery could help study infertility in certain cases.
News portal EurekAlert quoted Fu as saying: “We were interested in answering a fundamental question about the beginning of life. But in the process, we’ve uncovered a step that might malfunction for some people, and contribute to a couple’s difficulty conceiving. Now that we know SPRK1 plays a role here, its potential part in infertility can be further explored.”
Until now, enzyme SPRK1 was studied for its ability to splice ribonucleic acid (RNA) — an important step that enables translation of genes to proteins.
“But SRPK1 leads a double life — swapping protamines for histones once the sperm meets egg,” Fu added.
According to Fu, SPRK1 most likely started out playing this role in early embryogenesis, and later evolved the ability to splice RNA. That was how SPRK1 got to do the latter even when it was no longer needed for embryogenesis.
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