Decapping complex

The mRNA decapping complex is a protein complex in eukaryotic cells responsible for removal of the 5' cap.[1] The active enzyme of the decapping complex is the bilobed Nudix family enzyme Dcp2, which hydrolyzes 5' cap and releases 7mGDP and a 5'-monophosphorylated mRNA.[2] This decapped mRNA is inhibited for translation and will be degraded by exonucleases.[3] The core decapping complex is conserved in eukaryotes. Dcp2 is activated by Decapping Protein 1 (Dcp1) and in higher eukaryotes joined by the scaffold protein VCS.[4] Together with many other accessory proteins, the decapping complex assembles in P-bodies in the cytoplasm.

Yeast decapping complex

In yeast (S. cerevisiae), Dcp2 is joined by the decapping activator Dcp1, the helicase Dhh1, the exonuclease Xrn1, nonsense mediated decay factors Upf1, Upf2, and Upf3, the LSm complex, Pat1, and various other proteins. These proteins all localize to cytoplasmic structures called P-bodies. Notably in yeast there are no translation factors or ribosomal proteins inside P-bodies.[5]

Metazoan decapping complex

Higher eukaryotes have slightly different members of the decapping complex. The enzyme Dcp2 is still the catalytic subunit along with Dcp1, Xrn1, Upf1-3, the LSm complex, and the Dhh1 ortholog Rck/p-54. Proteins unique to plants and mammals include the beta propeller protein Hedls and the enhancer of decapping Edc3.[6] Structural details of the assembly of this complex are not known, only physical association by immunoprecipitation.

References
  1. Mugridge, Jeffrey S; Ziemniak, Marcin; Jemielity, Jacek; Gross, John D (November 2016). "Structural basis of mRNA cap recognition by Dcp1–Dcp2". Nature Structural & Molecular Biology. 23 (11): 987–994. doi:10.1038/nsmb.3301. ISSN 1545-9993. PMC 5113729. PMID 27694842.
  2. Mugridge, Jeffrey S; Ziemniak, Marcin; Jemielity, Jacek; Gross, John D (November 2016). "Structural basis of mRNA cap recognition by Dcp1–Dcp2". Nature Structural & Molecular Biology. 23 (11): 987–994. doi:10.1038/nsmb.3301. ISSN 1545-9993. PMC 5113729. PMID 27694842.
  3. Chantarachot T, Bailey-Serres J (January 2018). "Polysomes, Stress Granules, and Processing Bodies: A Dynamic Triumvirate Controlling Cytoplasmic mRNA Fate and Function". Plant Physiology. 176 (1): 254–269. doi:10.1104/pp.17.01468. PMC 5761823. PMID 29158329.
  4. Sieburth LE, Vincent JN (2018-12-17). "Beyond transcription factors: roles of mRNA decay in regulating gene expression in plants". F1000Research. 7: 1940. doi:10.12688/f1000research.16203.1. PMC 6305221. PMID 30613385.
  5. Parker R, Sheth U (March 2007). "P bodies and the control of mRNA translation and degradation". Molecular Cell. 25 (5): 635–46. doi:10.1016/j.molcel.2007.02.011. PMID 17349952.
  6. Fenger-Grøn M, Fillman C, Norrild B, Lykke-Andersen J (December 2005). "Multiple processing body factors and the ARE binding protein TTP activate mRNA decapping" (PDF). Molecular Cell. 20 (6): 905–15. doi:10.1016/j.molcel.2005.10.031. PMID 16364915. Archived from the original (PDF) on 2011-06-06.


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