3ax1
From Proteopedia
Molecular insights into miRNA processing by Arabidopsis Serrate
Structural highlights
FunctionSRRT_ARATH Acts as a mediator between the cap-binding complex (CBC) and both the pre-mRNA splicing and primary microRNAs (miRNAs) processing machinery. Required for proper processing of primary miRNAs to miRNAs, thereby playing a role in RNA-mediated gene silencing (RNAi) by miRNAs. Does not participate in sense post-transcriptional gene silencing. Acts as a regulator of meristem activity and adaxial leaf fate via the miRNA gene-silencing pathway by regulating the expression of PHB and by limiting the competence of shoot tissue to respond to KNOX expression. Its function is however not limited to miRNA-mediated repression of leaf polarity genes, but rather acts as a general regulator of primary microRNAs processing. Also critical for the accumulation of the trans-acting small interfering RNA (ta-siRNA). Required for pre-mRNA splicing.[1] [2] [3] [4] [5] Publication Abstract from PubMedIn plant, primary transcripts (pri-miRNAs) transcribed from miRNA genes by RNA polymerase II are first processed into stem-loop pre-miRNAs and further chopped into approximately 21 nt long miRNAs by RNase III-like enzyme DCL1. SERRATE (SE) protein is an essential component for miRNA processing by assisting DCL1 for accurate cleavage. Here we report the crystal structure of Arabidopsis SE core (residues 194-543) at 2.7 A. SE core adopts the 'walking man-like' topology with N-terminal alpha helices, C-terminal non-canonical zinc-finger domain and novel Middle domain resembling the leading leg, the lagging leg and the body, respectively. Pull-down assay shows that SE core provides the platform for HYL1 and DCL1 binding, whereas in vitro RNA binding and in vivo mutant rescue experiments suggest that the non-canonical zinc-finger domain coupled with C-terminal tail binds miRNA precursors. SE presumably works as a scaffold-like protein capable of binding both protein and RNA to guide the positioning of miRNA precursor toward DCL1 catalytic site within miRNA processing machinery in plant. Molecular insights into miRNA processing by Arabidopsis thaliana SERRATE.,Machida S, Chen HY, Adam Yuan Y Nucleic Acids Res. 2011 Jun 17. PMID:21685453[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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