A slicer-mediated mechanism for repeat-associated siRNA 5' end formation in Drosophila.
In Drosophila, repeat-associated small interfering RNAs (rasiRNAs) are produced in the germ line by a Dicer-independent pathway and function through the PIWI subfamily of Argonautes to ensure silencing of retrotransposons. We sequenced small RNAs associated with the PIWI subfamily member AGO3. Although other members of PIWI, Aubergine (Aub) and Piwi, associated with rasiRNAs derived mainly from the antisense strand of retrotransposons, AGO3-associated rasiRNAs arose mainly from the sense strand. Aub- and Piwi-associated rasiRNAs showed a strong preference for uracil at their 5' ends, and AGO3-associated rasiRNAs showed a strong preference for adenine at nucleotide 10. Comparisons between AGO3- and Aub-associated rasiRNAs revealed pairs of rasiRNAs showing complementarities in their first 10 nucleotides. Aub and AGO3 exhibited Slicer activity in vitro. These data support a model in which formation of a 5' terminus within rasiRNA precursors is guided by rasiRNAs originating from transcripts of the other strand in concert with the Slicer activity of PIWI.
Gunawardane
Lalith S
LS
Institute for Genome Research, University of Tokushima, Tokushima 770-8503, Japan.
Saito
Kuniaki
K
Nishida
Kazumichi M
KM
Miyoshi
Keita
K
Kawamura
Yoshinori
Y
Nagami
Tomoko
T
Siomi
Haruhiko
H
Siomi
Mikiko C
MC
D000595:Amino Acid Sequence; D000818:Animals; D060565:Argonaute Proteins; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015723:Gene Library; D008297:Male; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010053:Ovary / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D034743:RNA-Induced Silencing Complex; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D018626:Retroelements; D013737:Testis / Q000378:metabolism
C518392:AGO3 protein, Drosophila; D060565:Argonaute Proteins; D029721:Drosophila Proteins; D010448:Peptide Initiation Factors; D011506:Proteins; D034741:RNA, Small Interfering; D034743:RNA-Induced Silencing Complex; D011993:Recombinant Fusion Proteins; D018626:Retroelements; C436124:aub protein, Drosophila; C116498:piwi protein, Drosophila