RRF-1

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RRF-1

• Ruchira Ranaweera

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Clone summary
Clone name Insert size C. elegans Gene Name P(N) Protein/ Gene product
8A06-2 650bp apl-1 3.5 e-32 Amyloid Beta A4 Precursor like protein
8A06-4 850bp K10C3.5 1.5 e-35 Hypothetical protein
8A06-6 1750bp rrn-3.1 1.7 e-98 rRNA
8A06-7 1450bp rrf-1 2.4 e-52 RNA-directed RNA Polymerase
8A06-9 850bp rrn-3.1 1.7 e-98 rRNA
8A06-11 1400bp rrn-3.1 1.7 e-98 rRNA
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What is the function of rrf-1?

• RNA-directed RNA Polymerase
• Amplifies RNAi silencing
• Only required for RNAi in somatic cells, NOT
  germline

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What is an RNA-directed RNA Polymerase?

• Different from RNA polymerase used in
  transcription
• RdRp uses RNA as a template to create an RNA
  copy, or a cRNA
• Involved in RNAi amplification causing transitive
  RNA interference

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Blast-n search results

• Shows 78 sequence similarity in C. elegans
  cosmid F26A3
• Best matching ORF was rrf-1 coding region
• Chromosome I , 2.23
• exons 12 and 13
• Related gene ego-1, also an RdRP is downstream of
  rrf-1 in genome

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Protein Homology

• Putative Conserved RdRp domain found
• Extensive homology in nematodes (C. remanei vs.
  C. elegans, C. briggsae)
• Also homologous to other RdRp in plant species
  (Arabidopsis thaliana, Oryza Sativa)

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Protein Sequence Alignment

• Highly conserved sequence matches with other RdRp
  homologs in C. elegans
• Conserved across region with RdRp domain

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RNA interference

• RdRp amplifies siRNA-directed silencing
• Produces more copies of long dsRNA using trigger
  siRNA as a primer which can then be cleaved by
  Dicer
• The new siRNAs have unique specificities
• Amplified response allows for degradation of a
  large amount of dsRNA

www.pnas.orgcgidoi10.1073pnas.1232238100 Dillin,
A. The specifics of small interfering RNA
specificity
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Why have RNAi?

• First line of defense against viruses and
  transposons
• RdRp helps send immune response signal to other
  cells in organism
• Propagates a good adaptive immunity
• Vertebrates may have evolved past need for RdRp

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Future of RdRp and RNAi

• Mutants of rrf-1
• Study selective silencing of genes in germline
• Research
• Study gene expression and regulation without need
  for complete gene knockouts
• RNAi therapy
• Treat genetic diseases where genes have been
  incorrectly activated