5mdw

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Structure of ArfA(A18T) and RF2 bound to the 70S ribosome (pre-accommodated state)

Structural highlights

5mdw is a 10 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:Electron Microscopy, Resolution 3.06Å
Experimental data:Check to display Experimental Data
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

RS4_ECOLI One of two assembly initiator proteins for the 30S subunit, it binds directly to 16S rRNA where it nucleates assembly of the body of the 30S subunit.[1] [2] [3] With S5 and S12 plays an important role in translational accuracy; many suppressors of streptomycin-dependent mutants of protein S12 are found in this protein, some but not all of which decrease translational accuracy (ram, ribosomal ambiguity mutations).[4] [5] [6] Plays a role in mRNA unwinding by the ribosome, possibly by forming part of a processivity clamp.[7] [8] [9] Protein S4 is also a translational repressor protein, it controls the translation of the alpha-operon (which codes for S13, S11, S4, RNA polymerase alpha subunit, and L17) by binding to its mRNA.[10] [11] [12] Also functions as a rho-dependent antiterminator of rRNA transcription, increasing the synthesis of rRNA under conditions of excess protein, allowing a more rapid return to homeostasis. Binds directly to RNA polymerase.[13] [14] [15]

Publication Abstract from PubMed

Ribosomes stall when they encounter the end of messenger RNA (mRNA) without an in-frame stop codon. In bacteria, these "nonstop" complexes can be rescued by alternative ribosome-rescue factor A (ArfA). We used electron cryomicroscopy to determine structures of ArfA bound to the ribosome with 3'-truncated mRNA, at resolutions ranging from 3.0 to 3.4 angstroms. ArfA binds within the ribosomal mRNA channel and substitutes for the absent stop codon in the A site by specifically recruiting release factor 2 (RF2), initially in a compact preaccommodated state. A similar conformation of RF2 may occur on stop codons, suggesting a general mechanism for release-factor-mediated translational termination in which a conformational switch leads to peptide release only when the appropriate signal is present in the A site.

Translational termination without a stop codon.,James NR, Brown A, Gordiyenko Y, Ramakrishnan V Science. 2016 Dec 16;354(6318):1437-1440. Epub 2016 Dec 1. PMID:27934701[16]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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See Also

References

  1. ↑ Nowotny V, Nierhaus KH. Assembly of the 30S subunit from Escherichia coli ribosomes occurs via two assembly domains which are initiated by S4 and S7. Biochemistry. 1988 Sep 6;27(18):7051-5. PMID:2461734
  2. ↑ Torres M, Condon C, Balada JM, Squires C, Squires CL. Ribosomal protein S4 is a transcription factor with properties remarkably similar to NusA, a protein involved in both non-ribosomal and ribosomal RNA antitermination. EMBO J. 2001 Jul 16;20(14):3811-20. PMID:11447122 doi:10.1093/emboj/20.14.3811
  3. ↑ Takyar S, Hickerson RP, Noller HF. mRNA helicase activity of the ribosome. Cell. 2005 Jan 14;120(1):49-58. PMID:15652481 doi:10.1016/j.cell.2004.11.042
  4. ↑ Nowotny V, Nierhaus KH. Assembly of the 30S subunit from Escherichia coli ribosomes occurs via two assembly domains which are initiated by S4 and S7. Biochemistry. 1988 Sep 6;27(18):7051-5. PMID:2461734
  5. ↑ Torres M, Condon C, Balada JM, Squires C, Squires CL. Ribosomal protein S4 is a transcription factor with properties remarkably similar to NusA, a protein involved in both non-ribosomal and ribosomal RNA antitermination. EMBO J. 2001 Jul 16;20(14):3811-20. PMID:11447122 doi:10.1093/emboj/20.14.3811
  6. ↑ Takyar S, Hickerson RP, Noller HF. mRNA helicase activity of the ribosome. Cell. 2005 Jan 14;120(1):49-58. PMID:15652481 doi:10.1016/j.cell.2004.11.042
  7. ↑ Nowotny V, Nierhaus KH. Assembly of the 30S subunit from Escherichia coli ribosomes occurs via two assembly domains which are initiated by S4 and S7. Biochemistry. 1988 Sep 6;27(18):7051-5. PMID:2461734
  8. ↑ Torres M, Condon C, Balada JM, Squires C, Squires CL. Ribosomal protein S4 is a transcription factor with properties remarkably similar to NusA, a protein involved in both non-ribosomal and ribosomal RNA antitermination. EMBO J. 2001 Jul 16;20(14):3811-20. PMID:11447122 doi:10.1093/emboj/20.14.3811
  9. ↑ Takyar S, Hickerson RP, Noller HF. mRNA helicase activity of the ribosome. Cell. 2005 Jan 14;120(1):49-58. PMID:15652481 doi:10.1016/j.cell.2004.11.042
  10. ↑ Nowotny V, Nierhaus KH. Assembly of the 30S subunit from Escherichia coli ribosomes occurs via two assembly domains which are initiated by S4 and S7. Biochemistry. 1988 Sep 6;27(18):7051-5. PMID:2461734
  11. ↑ Torres M, Condon C, Balada JM, Squires C, Squires CL. Ribosomal protein S4 is a transcription factor with properties remarkably similar to NusA, a protein involved in both non-ribosomal and ribosomal RNA antitermination. EMBO J. 2001 Jul 16;20(14):3811-20. PMID:11447122 doi:10.1093/emboj/20.14.3811
  12. ↑ Takyar S, Hickerson RP, Noller HF. mRNA helicase activity of the ribosome. Cell. 2005 Jan 14;120(1):49-58. PMID:15652481 doi:10.1016/j.cell.2004.11.042
  13. ↑ Nowotny V, Nierhaus KH. Assembly of the 30S subunit from Escherichia coli ribosomes occurs via two assembly domains which are initiated by S4 and S7. Biochemistry. 1988 Sep 6;27(18):7051-5. PMID:2461734
  14. ↑ Torres M, Condon C, Balada JM, Squires C, Squires CL. Ribosomal protein S4 is a transcription factor with properties remarkably similar to NusA, a protein involved in both non-ribosomal and ribosomal RNA antitermination. EMBO J. 2001 Jul 16;20(14):3811-20. PMID:11447122 doi:10.1093/emboj/20.14.3811
  15. ↑ Takyar S, Hickerson RP, Noller HF. mRNA helicase activity of the ribosome. Cell. 2005 Jan 14;120(1):49-58. PMID:15652481 doi:10.1016/j.cell.2004.11.042
  16. ↑ James NR, Brown A, Gordiyenko Y, Ramakrishnan V. Translational termination without a stop codon. Science. 2016 Dec 16;354(6318):1437-1440. Epub 2016 Dec 1. PMID:27934701 doi:http://dx.doi.org/10.1126/science.aai9127

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5mdw, resolution 3.06Å

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