Friday, January 23, 2009

Retrotransposon fun

In PNAS this month:
Non-LTR retrotransposons encode noncanonical RRM domains in their first open reading frame.

(PNAS is the Proceedings of the National Academy of Sciences and is one of the more presitgious journals, perhaps just a shade below Science and Nature in prestige).

Not the easiest title to parse but the paper puts another piece into the retrotransposon puzzle.

In the paper the authors determined the structure of a protein (L1ORF1p), which is encoded by a parasitic genetic element and which is responsible for its mobility.

The LINE-1 retrotransposon is a mobile genetic element that can multiply and insert itself into chromosomal DNA at many different locations. This disturbs the genetic code at the site of integration, which can have serious consequences for the organism. Presently, approximately 17% of our DNA consist of LINE-1 sequences. This is an enormous proportion if one considers that the roughly 30.000 human proteins are encoded by less that 5% of the DNA.

Understanding the structure of the L1ORF1p protein now allows a much more precise investigation of the mechanism of LINE-1 mobilization. This provides new insight into the relation between retrotransposons and retroviruses and probably also into certain evolutionary processes in humans and animals. Moreover, the researchers assume that the mechanism of LINE-1 retrotransposition can be exploited one day to precisely insert genetic information into specific locations. This would be an alternative to contemporary, less location-specific methods that are based on a retroviral mechanism.

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