Artigos recentes: Nature Structural & Molecular Biology - September 2009, Volume 16 No 9 pp899-1001

Cabin1 restrains p53 activity on chromatin -pp910 - 915

Hyonchol Jang, Soo-Youn Choi, Eun-Jung Cho & Hong-Duk Youn

doi:10.1038/nsmb.1657

The tumor suppressor p53 activates the transcription of a number of genes under conditions of genotoxic stress. Some of these regulated promoters show p53 occupancy even under normal conditions. Now calcineurin-binding protein 1 (Cabin1) is shown to keep p53 inactive in these promoters.

Abstract- Cabin1 restrains p53 activity on chromatin | Full Text- Cabin1 restrains p53 activity on chromatin | PDF (1,250 KB)- Cabin1 restrains p53 activity on chromatin | Supplementary information

See also: News and Views by Tolstonog & Deppert

Fast ribozyme cleavage releases transcripts from RNA polymerase II and aborts co-transcriptional pre-mRNA processing -pp916 - 922

Nova Fong, Marie Öhman & David L Bentley

doi:10.1038/nsmb.1652

Co-transcriptional splicing of pre-mRNAs has been proposed to involve exon tethering to the elongating RNA polymerase II. By inserting a fast-cleaving ribozyme in the nascent transcript, the linear integrity of the transcript is found to be key to splicing, arguing against tethering and for a pathway that clears such disrupted transcripts.

Abstract- Fast ribozyme cleavage releases transcripts from RNA polymerase II and aborts co-transcriptional pre-mRNA processing | Full Text- Fast ribozyme cleavage releases transcripts from RNA polymerase II and aborts co-transcriptional pre-mRNA processing | PDF (1,518 KB)- Fast ribozyme cleavage releases transcripts from RNA polymerase II and aborts co-transcriptional pre-mRNA processing | Supplementary information

See also: News and Views by Klaue & Hertel

A macrodomain-containing histone rearranges chromatin upon sensing PARP1 activation -pp923 - 929

Gyula Timinszky, Susanne Till, Paul O Hassa, Michael Hothorn, Georg Kustatscher, Bianca Nijmeijer, Julien Colombelli, Matthias Altmeyer, Ernst H K Stelzer, Klaus Scheffzek, Michael O Hottiger & Andreas G Ladurner

doi:10.1038/nsmb.1664

• PDB code

  • 3IID
  • 3IIF

• 3D view

  • 3IID
  • 3IIF

Phosphorylation-dependent SUMOylation of MEF2A promotes postsynaptic dendrite differentiation. Analyses now reveal that a surface on the SUMO E2 UBC9 is responsible for integrating phosphorylation signal recognition and SUMOylation and suggests that regulation of some SUMO substrate recognition events may have evolved to use the E2 rather than an E3 ligase.

Abstract- A macrodomain-containing histone rearranges chromatin upon sensing PARP1 activation | Full Text- A macrodomain-containing histone rearranges chromatin upon sensing PARP1 activation | PDF (1,262 KB)- A macrodomain-containing histone rearranges chromatin upon sensing PARP1 activation | Supplementary information

See also: News and Views by Kraus

The molecular basis for the regulation of the cap-binding complex by the importins -pp930 - 937

Sandra M G Dias, Kristin F Wilson, Katherine S Rojas, Andre L B Ambrosio & Richard A Cerione

doi:10.1038/nsmb.1649

• PDB code

  • 3FEY
  • 3FEX

• 3D view

  • 3FEY
  • 3FEX

The cap binding complex (CBC) interacts with mRNAs and snRNAs and accompanies them to the cytoplasm, where they are released and CBC is imported back into the nucleus by the importin complex. Multiple approaches are now combined to gain structural and functional insights into the regulation and coordination of these CBC interactions.

Abstract- The molecular basis for the regulation of the cap-binding complex by the importins | Full Text- The molecular basis for the regulation of the cap-binding complex by the importins | PDF (1,199 KB)- The molecular basis for the regulation of the cap-binding complex by the importins | Supplementary information

Dynamics and function of compact nucleosome arrays -pp938 - 944

Michael G Poirier, Eugene Oh, Hannah S Tims & Jonathan Widom

doi:10.1038/nsmb.1650

Nucleosomes can interfere with DNA binding by factors, but previous work showed that protein-binding sites on a single nucleosome are accessible. Dynamics in the context of higher-order chromatin structure are now examined, with compaction dynamics and DNA-binding site exposure on a centrally placed nucleosome in an array assessed.

Abstract- Dynamics and function of compact nucleosome arrays | Full Text- Dynamics and function of compact nucleosome arrays | PDF (906 KB)- Dynamics and function of compact nucleosome arrays | Supplementary information

A molecular basis for phosphorylation-dependent SUMO conjugation by the E2 UBC9 -pp945 - 952

Firaz Mohideen, Allan D Capili, Parizad M Bilimoria, Tomoko Yamada, Azad Bonni & Christopher D Lima

doi:10.1038/nsmb.1648

Phosphorylation-dependent SUMOylation of MEF2A promotes postsynaptic dendrite differentiation. Analyses now reveal that a surface on the SUMO E2 UBC9 is responsible for integrating phosphorylation signal recognition and SUMOylation and suggests that regulation of some SUMO substrate recognition events may have evolved to use the E2 rather than an E3 ligase.

Abstract- A molecular basis for phosphorylation-dependent SUMO conjugation by the E2 UBC9 | Full Text- A molecular basis for phosphorylation-dependent SUMO conjugation by the E2 UBC9 | PDF (1,698 KB)- A molecular basis for phosphorylation-dependent SUMO conjugation by the E2 UBC9 | Supplementary information

Structural determinants of miRNAs for RISC loading and slicer-independent unwinding -pp953 - 960

Tomoko Kawamata, Hervé Seitz & Yukihide Tomari

doi:10.1038/nsmb.1630

miRNAs are loaded onto Argonautes (Agos) to guide silencing of targets, but duplex unwinding is required for targeting. Detection of Drosophila Ago1 complexes containing the duplexed or unwound miRNA now give insight into the basis for cleavage-independent unwinding of miRNA duplexes to generate a functional, mature complex.

Abstract- Structural determinants of miRNAs for RISC loading and slicer-independent unwinding | Full Text- Structural determinants of miRNAs for RISC loading and slicer-independent unwinding | PDF (2,452 KB)- Structural determinants of miRNAs for RISC loading and slicer-independent unwinding | Supplementary information

Existence of a microRNA pathway in anucleate platelets -pp961 - 966

Patricia Landry, Isabelle Plante, Dominique L Ouellet, Marjorie P Perron, Guy Rousseau & Patrick Provost

doi:10.1038/nsmb.1651

Platelets are anucleate elements in the cardiovascular system involved in clotting. Platelets are now found to contain microRNAs and the key cytoplasmic elements of a processing and effector pathway, suggesting that platelet mRNAs may be subjected to microRNA regulation.

Abstract- Existence of a microRNA pathway in anucleate platelets | Full Text- Existence of a microRNA pathway in anucleate platelets | PDF (1,347 KB)- Existence of a microRNA pathway in anucleate platelets | Supplementary information

Template strand scrunching during DNA gap repair synthesis by human polymerase -pp967 - 972

Miguel Garcia-Diaz, Katarzyna Bebenek, Andres A Larrea, Jody M Havener, Lalith Perera, Joseph M Krahn, Lars C Pedersen, Dale A Ramsden & Thomas A Kunkel

doi:10.1038/nsmb.1654

• PDB code

  • 3HWT
  • 3HW8
  • 3HX0

• 3D view

  • 3HWT
  • 3HW8
  • 3HX0

X family DNA polymerases can fill short DNA gaps by binding both the 5' and 3' ends of the gap. What happens to the template strand is now revealed in the crystal structure of human polymerase bound to a 2-nucleotide gap substrate. The template strand is scrunched, with the additional base in an extrahelical position going into an enzyme pocket.

Abstract- Template strand scrunching during DNA gap repair synthesis by human polymerase [lambda] | Full Text- Template strand scrunching during DNA gap repair synthesis by human polymerase | PDF (1,236 KB)- Template strand scrunching during DNA gap repair synthesis by human polymerase | Supplementary information

Molecular mechanisms for protein-encoded inheritance -pp973 - 978

Jed J W Wiltzius, Meytal Landau, Rebecca Nelson, Michael R Sawaya, Marcin I Apostol, Lukasz Goldschmidt, Angela B Soriaga, Duilio Cascio, Kanagalaghatta Rajashankar & David Eisenberg

doi:10.1038/nsmb.1643

• PDB code

  • 3FVA
  • 3FQP
  • 3FR1
  • 3FTH
  • 3FPO
  • 3FOD
  • 3FTR
  • 3FTK
  • 3FTL

• 3D view

  • 3FVA
  • 3FQP
  • 3FR1
  • 3FTH
  • 3FPO
  • 3FOD
  • 3FTR
  • 3FTK
  • 3FTL

Prions can adopt a transmissible -sheet-rich conformation and also form strains with different structural and biological properties. Polymorphic crystal structures of peptides from prion- and other amyloid-forming proteins suggest the structural basis for prion strains, revealing two potential mechanisms: packing and segmental polymorphism.

Abstract- Molecular mechanisms for protein-encoded inheritance | Full Text- Molecular mechanisms for protein-encoded inheritance | PDF (1,013 KB)- Molecular mechanisms for protein-encoded inheritance | Supplementary information

Structural basis of high-fidelity DNA synthesis by yeast DNA polymerase -pp979 - 986

Michael K Swan, Robert E Johnson, Louise Prakash, Satya Prakash & Aneel K Aggarwal

doi:10.1038/nsmb.1663

• PDB code

  • 3IAY

• 3D view

  • 3IAY

DNA polymerase (Pol ) has a crucial role in eukaryotic replication. Now the crystal structure of the yeast DNA Pol catalytic subunit in complex with template primer and incoming nucleotide is presented at 2.0-Å resolution, providing insight into its high fidelity and a framework to understand the effects of mutations involved in tumorigenesis.

Abstract- Structural basis of high-fidelity DNA synthesis by yeast DNA polymerase [delta] | Full Text- Structural basis of high-fidelity DNA synthesis by yeast DNA polymerase | PDF (1,468 KB)- Structural basis of high-fidelity DNA synthesis by yeast DNA polymerase | Supplementary information