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Nat Commun. 2019 Feb 19;10(1):828. doi: 10.1038/s41467-019-08803-z.

Decoding the 5' nucleotide bias of PIWI-interacting RNAs.

Author information

1
National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA.
2
PhD Program in Biological and Biomedical Sciences, Harvard Medical School, Boston, MA 02115, USA.
3
W.M. Keck Structural Biology Laboratory, Howard Hughes Medical Institute, Cold Spring Harbor, 11724, USA.
4
Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11724, USA.
5
Department of Biology, Johns Hopkins University, Baltimore, MD, 21218, USA.
6
National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, 20892, USA.
7
National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA. astrid.haase@nih.gov.

Abstract

PIWI-interacting RNAs (piRNAs) are at the center of a small RNA-based immune system that defends genomes against the deleterious action of mobile genetic elements (transposons). PiRNAs are highly variable in sequence with extensive targeting potential. Their diversity is restricted by their preference to start with a Uridine (U) at the 5' most position (1U-bias), a bias that remains poorly understood. Here we uncover that the 1U-bias of Piwi-piRNAs is established by consecutive discrimination against all nucleotides but U, first during piRNA biogenesis and then upon interaction with Piwi's specificity loop. Sequence preferences during piRNA processing also restrict U across the piRNA body with the potential to directly impact target recognition. Overall, the uncovered signatures could modulate specificity and efficacy of piRNA-mediated transposon restriction, and provide a substrate for purifying selection in the ongoing arms race between genomes and their mobile parasites.

PMID:
30783109
PMCID:
PMC6381166
DOI:
10.1038/s41467-019-08803-z
[Indexed for MEDLINE]
Free PMC Article

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