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  • The EMBO Journal (2004) 23, 3356 - 3364
  • doi:10.1038/sj.emboj.7600340

Published online: 29 July 2004

MicroRNA control of PHABULOSA in leaf development: importance of pairing to the microRNA 5' region

Allison C Mallory1,a, Brenda J Reinhart1,2,a, Matthew W Jones-Rhoades1,3, Guiliang Tang4, Phillip D Zamore4, M Kathryn Barton2 and David P Bartel1,3

  1. Whitehead Institute for Biomedical Research, Cambridge, MA, USA
  2. Department of Plant Biology, Carnegie Institution of Washington, Stanford, CA, USA
  3. Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
  4. Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA

Correspondence to:

M Kathryn Barton, Department of Plant Biology, Carnegie Institution of Washington, Stanford, CA 94305, USA. E-mail: kbarton@stanford.edu

David P Bartel, Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142-1479, USA. E-mail: dbartel@wi.mit.edu

aThese authors contributed equally to this work

Received 20 January 2004; Accepted 30 June 2004

MicroRNAs (miRNAs) are approx22-nucleotide noncoding RNAs that can regulate gene expression by directing mRNA degradation or inhibiting productive translation. Dominant mutations in PHABULOSA (PHB) and PHAVOLUTA (PHV) map to a miR165/166 complementary site and impair miRNA-guided cleavage of these mRNAs in vitro. Here, we confirm that disrupted miRNA pairing, not changes in PHB protein sequence, causes the developmental defects in phb-d mutants. In planta, disrupting miRNA pairing near the center of the miRNA complementary site had far milder developmental consequences than more distal mismatches. These differences correlated with differences in miRNA-directed cleavage efficiency in vitro, where mismatch scanning revealed more tolerance for mismatches at the center and 3' end of the miRNA compared to mismatches to the miRNA 5' region. In this respect, miR165/166 resembles animal miRNAs in its pairing requirements. Pairing to the 5' portion of the small silencing RNA appears crucial regardless of the mode of post-transcriptional repression or whether it occurs in plants or animals, supporting a model in which this region of the silencing RNA nucleates pairing to its target.

  • Keywords:

    • miRNAs,
    • PHABULOSA,
    • RNA-directed RNA cleavage,
    • RNAi,
    • siRNA