Homodimerization of HYL1 ensures the correct selection of cleavage sites in primary miRNA.
Bottom Line: Disruption of HYL1 homodimerization causes incorrect cleavage at sites in pri-miRNA without interrupting the interaction of HYL1 with DCL1 and accumulation of pri-miRNAs in HYL1/pri-miRNA complexes, leading to a reduction in the efficiency and accuracy of miRNAs that results in strong mutant phenotypes of the plants.HYL1 homodimers may function as a molecular anchor for DCL1 to cleave at a distance from the ssRNA-dsRNA junction in pri-miRNA.These results suggest that HYL1 ensures the correct selection of pri-miRNA cleavage sites through homodimerization and thus contributes to gene silencing and plant development.
Affiliation: National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.Show MeSH
Mentions: To examine whether the deficiency in HYL1 dimerization affects miRNA biogenesis, we performed northern blotting to detect the accumulation of miRNAs in the hyl1-2 mutants and transgenic plants with HYL1 mutations. In the hyl1-2;G147E, hyl1-2;L165E plants, the accumulation of miR156, miR166, miR172 and miR319 was much less than that in wild-type plants (Figure 5A). By contrast, miR156-targeted SPL9 and miR165/6-targeted REV genes were up-regulated in these plants (Figure 5B). Moreover, the accumulation of these miRNAs in hyl1-2;T146E, hyl1-2;I158E and hyl1-2;L166E was much greater than that in hyl1-2, whereas the target genes SPL9 and REV were down-regulated to the levels almost equal to those of the wild-type.
Affiliation: National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.