| Structural highlights
Function
[SAC3_YEAST] Component of the SAC3-THP1 complex, which functions in transcription-coupled mRNA export from the nucleus to the cytoplasm. SAC3-THP1 functions in docking export-competent ribonucleoprotein particles (mRNPs) to the nuclear entrance of the nuclear pore complex (nuclear basket), by association with components of the nuclear mRNA export machinery (MEX67-MTR2 and SUB2) in the nucleoplasm and the nucleoporin NUP1 at the nuclear basket.[1] [2] [SEM1_YEAST] Versatile protein that might stabilize multiple protein complexes involved in diverse pathways. Subunit of the 26S proteasome which plays a role in ubiquitin-dependent proteolysis. Associates also with the TREX-2 complex that is required for transcription-coupled mRNA export, and the COP9 signalosome, which is involved in deneddylation.[3] [4] [THP1_YEAST] Component of the SAC3-THP1 complex, which functions in transcription-coupled mRNA export from the nucleus to the cytoplasm. SAC3-THP1 functions in docking export-competent ribonucleoprotein particles (mRNPs) to the nuclear entrance of the nuclear pore complex (nuclear basket), by association with components of the nuclear mRNA export machinery (MEX67-MTR2 and SUB2) in the nucleoplasm and the nucleoporin NUP1 at the nuclear basket. THP1 binds to RNA in vitro.[5] [6] [7]
Publication Abstract from PubMed
Transcription-export complex 2 (TREX-2 complex) facilitates the localization of actively transcribing genes to the nuclear periphery and also functions to contribute to the generation of export-competent mRNPs through interactions with the general mRNA nuclear export factor Mex67:Mtr2. The TREX-2 complex is based on a Sac3 scaffold to which Thp1, Sem1, Cdc31, and Sus1 bind. TREX-2 can be subdivided into two modules: one, in which Thp1 and Sem1 bind to the Sac3M region (residues approximately 100-551), and the other in which Cdc31 and two Sus1 chains bind to the Sac3CID region (residues approximately 710-805). Complementary structural analyses using X-ray crystallography, electron microscopy, and small-angle X-ray scattering of the Saccharomyces cerevisiae TREX-2 complex, expressed using Baculovirus-infected Sf9 cells, have indicated that the TPR-like repeats of the Sac3M region extend considerably further towards the N-terminus than previously thought, and also indicate that this region and Sac3CID:Sus1:Cdc31 region of the S. cerevisiae complex are structurally independent. Although the density visible accounted for only approximately 100kDa, a 5.3A resolution cryo-EM reconstruction was obtained of the M-region of TREX-2 that showed an additional three putative alpha-helices extending towards the Sac3 N-terminus and these helices were also seen in a 4.9A resolution structure obtained by X-ray crystallography. SUMMARY STATEMENT: We describe the expression, purification and structural characterization of the S. cerevisiae TREX-2 complex and demonstrate that the Sac3 TPR-like repeats are more extensive than previously thought and that the M- and CID-regions do not appear to have a defined spatial orientation.
The Sac3 TPR-like region in the Saccharomyces cerevisiae TREX-2 complex is more extensive but independent of the CID region.,Aibara S, Bai XC, Stewart M J Struct Biol. 2016 Jul 12. pii: S1047-8477(16)30148-4. doi:, 10.1016/j.jsb.2016.07.007. PMID:27422657[8]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Fischer T, Strasser K, Racz A, Rodriguez-Navarro S, Oppizzi M, Ihrig P, Lechner J, Hurt E. The mRNA export machinery requires the novel Sac3p-Thp1p complex to dock at the nucleoplasmic entrance of the nuclear pores. EMBO J. 2002 Nov 1;21(21):5843-52. PMID:12411502
- ↑ Gallardo M, Luna R, Erdjument-Bromage H, Tempst P, Aguilera A. Nab2p and the Thp1p-Sac3p complex functionally interact at the interface between transcription and mRNA metabolism. J Biol Chem. 2003 Jun 27;278(26):24225-32. Epub 2003 Apr 17. PMID:12702719 doi:http://dx.doi.org/10.1074/jbc.M302900200
- ↑ Faza MB, Kemmler S, Jimeno S, Gonzalez-Aguilera C, Aguilera A, Hurt E, Panse VG. Sem1 is a functional component of the nuclear pore complex-associated messenger RNA export machinery. J Cell Biol. 2009 Mar 23;184(6):833-46. doi: 10.1083/jcb.200810059. Epub 2009 Mar, 16. PMID:19289793 doi:http://dx.doi.org/10.1083/jcb.200810059
- ↑ Sone T, Saeki Y, Toh-e A, Yokosawa H. Sem1p is a novel subunit of the 26 S proteasome from Saccharomyces cerevisiae. J Biol Chem. 2004 Jul 2;279(27):28807-16. Epub 2004 Apr 26. PMID:15117943 doi:http://dx.doi.org/10.1074/jbc.M403165200
- ↑ Gallardo M, Aguilera A. A new hyperrecombination mutation identifies a novel yeast gene, THP1, connecting transcription elongation with mitotic recombination. Genetics. 2001 Jan;157(1):79-89. PMID:11139493
- ↑ Fischer T, Strasser K, Racz A, Rodriguez-Navarro S, Oppizzi M, Ihrig P, Lechner J, Hurt E. The mRNA export machinery requires the novel Sac3p-Thp1p complex to dock at the nucleoplasmic entrance of the nuclear pores. EMBO J. 2002 Nov 1;21(21):5843-52. PMID:12411502
- ↑ Gallardo M, Luna R, Erdjument-Bromage H, Tempst P, Aguilera A. Nab2p and the Thp1p-Sac3p complex functionally interact at the interface between transcription and mRNA metabolism. J Biol Chem. 2003 Jun 27;278(26):24225-32. Epub 2003 Apr 17. PMID:12702719 doi:http://dx.doi.org/10.1074/jbc.M302900200
- ↑ Aibara S, Bai XC, Stewart M. The Sac3 TPR-like region in the Saccharomyces cerevisiae TREX-2 complex is more extensive but independent of the CID region. J Struct Biol. 2016 Jul 12. pii: S1047-8477(16)30148-4. doi:, 10.1016/j.jsb.2016.07.007. PMID:27422657 doi:http://dx.doi.org/10.1016/j.jsb.2016.07.007
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