Functional mapping of the plant small RNA methyltransferase: HEN1 physically interacts with HYL1 and DICER-LIKE 1 proteins.

Simona Baranauskė, Milda Mickutė, Alexandra Plotnikova, Andreas Finke, Česlovas Venclovas, Saulius Klimašauskas, Giedrius Vilkaitis

Nucleic acids research 2015 Mar 11

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Methylation of 3'-terminal nucleotides of miRNA/miRNA* is part of miRNAs biogenesis in plants but is not found in animals. In Arabidopsis thaliana this reaction is carried out by a multidomain AdoMet-dependent 2'-O-methyltransferase HEN1. Using deletion and structure-guided mutational analysis, we show that the double-stranded RNA-binding domains R(1) and R(2) of HEN1 make significant but uneven contributions to substrate RNA binding, and map residues in each domain responsible for this function. Using GST pull-down assays and yeast two-hybrid analysis we demonstrate direct HEN1 interactions, mediated by its FK506-binding protein-like domain and R(2) domain, with the microRNA biogenesis protein HYL1. Furthermore, we find that HEN1 forms a complex with DICER-LIKE 1 (DCL1) ribonuclease, another key protein involved in miRNA biogenesis machinery. In contrast, no direct interaction is detectable between HEN1 and SERRATE. On the basis of these findings, we propose a mechanism of plant miRNA maturation which involves binding of the HEN1 methyltransferase to the DCL1•HYL1•miRNA complex excluding the SERRATE protein. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Citation

Simona Baranauskė, Milda Mickutė, Alexandra Plotnikova, Andreas Finke, Česlovas Venclovas, Saulius Klimašauskas, Giedrius Vilkaitis. Functional mapping of the plant small RNA methyltransferase: HEN1 physically interacts with HYL1 and DICER-LIKE 1 proteins. Nucleic acids research. 2015 Mar 11;43(5):2802-12