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| Line 6: |
Line 6: |
| | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=ADP:ADENOSINE-5-DIPHOSPHATE'>ADP</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr> | | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=ADP:ADENOSINE-5-DIPHOSPHATE'>ADP</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr> |
| | <tr id='NonStdRes'><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=HIC:4-METHYL-HISTIDINE'>HIC</scene>, <scene name='pdbligand=UNK:UNKNOWN'>UNK</scene></td></tr> | | <tr id='NonStdRes'><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=HIC:4-METHYL-HISTIDINE'>HIC</scene>, <scene name='pdbligand=UNK:UNKNOWN'>UNK</scene></td></tr> |
| - | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5jlf FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5jlf OCA], [http://pdbe.org/5jlf PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=5jlf RCSB], [http://www.ebi.ac.uk/pdbsum/5jlf PDBsum]</span></td></tr> | + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5jlf FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5jlf OCA], [http://pdbe.org/5jlf PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=5jlf RCSB], [http://www.ebi.ac.uk/pdbsum/5jlf PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=5jlf ProSAT]</span></td></tr> |
| | </table> | | </table> |
| | == Function == | | == Function == |
| Line 12: |
Line 12: |
| | <div style="background-color:#fffaf0;"> | | <div style="background-color:#fffaf0;"> |
| | == Publication Abstract from PubMed == | | == Publication Abstract from PubMed == |
| - | Filamentous actin (F-actin) is the major protein of muscle thin filaments, and actin microfilaments are the main component of the eukaryotic cytoskeleton. Mutations in different actin isoforms lead to early-onset autosomal dominant non-syndromic hearing loss, familial thoracic aortic aneurysms and dissections, and multiple variations of myopathies. In striated muscle fibres, the binding of myosin motors to actin filaments is mainly regulated by tropomyosin and troponin. Tropomyosin also binds to F-actin in smooth muscle and in non-muscle cells and stabilizes and regulates the filaments there in the absence of troponin. Although crystal structures for monomeric actin (G-actin) are available, a high-resolution structure of F-actin is still missing, hampering our understanding of how disease-causing mutations affect the function of thin muscle filaments and microfilaments. Here we report the three-dimensional structure of F-actin at a resolution of 3.7 A in complex with tropomyosin at a resolution of 6.5 A, determined by electron cryomicroscopy. The structure reveals that the D-loop is ordered and acts as a central region for hydrophobic and electrostatic interactions that stabilize the F-actin filament. We clearly identify map density corresponding to ADP and Mg2+ and explain the possible effect of prominent disease-causing mutants. A comparison of F-actin with G-actin reveals the conformational changes during filament formation and identifies the D-loop as their key mediator. We also confirm that negatively charged tropomyosin interacts with a positively charged groove on F-actin. Comparison of the position of tropomyosin in F-actin-tropomyosin with its position in our previously determined F-actin-tropomyosin-myosin structure reveals a myosin-induced transition of tropomyosin. Our results allow us to understand the role of individual mutations in the genesis of actin- and tropomyosin-related diseases and will serve as a strong foundation for the targeted development of drugs.
| + | The interaction of myosin with actin filaments is the central feature of muscle contraction and cargo movement along actin filaments of the cytoskeleton. The energy for these movements is generated during a complex mechanochemical reaction cycle. Crystal structures of myosin in different states have provided important structural insights into the myosin motor cycle when myosin is detached from F-actin. The difficulty of obtaining diffracting crystals, however, has prevented structure determination by crystallography of actomyosin complexes. Thus, although structural models exist of F-actin in complex with various myosins, a high-resolution structure of the F-actin-myosin complex is missing. Here, using electron cryomicroscopy, we present the structure of a human rigor actomyosin complex at an average resolution of 3.9 A. The structure reveals details of the actomyosin interface, which is mainly stabilized by hydrophobic interactions. The negatively charged amino (N) terminus of actin interacts with a conserved basic motif in loop 2 of myosin, promoting cleft closure in myosin. Surprisingly, the overall structure of myosin is similar to rigor-like myosin structures in the absence of F-actin, indicating that F-actin binding induces only minimal conformational changes in myosin. A comparison with pre-powerstroke and intermediate (Pi-release) states of myosin allows us to discuss the general mechanism of myosin binding to F-actin. Our results serve as a strong foundation for the molecular understanding of cytoskeletal diseases, such as autosomal dominant hearing loss and diseases affecting skeletal and cardiac muscles, in particular nemaline myopathy and hypertrophic cardiomyopathy. |
| | | | |
| - | Structure of the F-actin--tropomyosin complex.,von der Ecken J, Muller M, Lehman W, Manstein DJ, Penczek PA, Raunser S Nature. 2014 Dec 1. doi: 10.1038/nature14033. PMID:25470062<ref>PMID:25470062</ref>
| + | Cryo-EM structure of a human cytoplasmic actomyosin complex at near-atomic resolution.,von der Ecken J, Heissler SM, Pathan-Chhatbar S, Manstein DJ, Raunser S Nature. 2016 Jun 30;534(7609):724-8. PMID:27324845<ref>PMID:27324845</ref> |
| | | | |
| | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> |
| Structural highlights
Function
[ACTS_RABIT] Actins are highly conserved proteins that are involved in various types of cell motility and are ubiquitously expressed in all eukaryotic cells.
Publication Abstract from PubMed
The interaction of myosin with actin filaments is the central feature of muscle contraction and cargo movement along actin filaments of the cytoskeleton. The energy for these movements is generated during a complex mechanochemical reaction cycle. Crystal structures of myosin in different states have provided important structural insights into the myosin motor cycle when myosin is detached from F-actin. The difficulty of obtaining diffracting crystals, however, has prevented structure determination by crystallography of actomyosin complexes. Thus, although structural models exist of F-actin in complex with various myosins, a high-resolution structure of the F-actin-myosin complex is missing. Here, using electron cryomicroscopy, we present the structure of a human rigor actomyosin complex at an average resolution of 3.9 A. The structure reveals details of the actomyosin interface, which is mainly stabilized by hydrophobic interactions. The negatively charged amino (N) terminus of actin interacts with a conserved basic motif in loop 2 of myosin, promoting cleft closure in myosin. Surprisingly, the overall structure of myosin is similar to rigor-like myosin structures in the absence of F-actin, indicating that F-actin binding induces only minimal conformational changes in myosin. A comparison with pre-powerstroke and intermediate (Pi-release) states of myosin allows us to discuss the general mechanism of myosin binding to F-actin. Our results serve as a strong foundation for the molecular understanding of cytoskeletal diseases, such as autosomal dominant hearing loss and diseases affecting skeletal and cardiac muscles, in particular nemaline myopathy and hypertrophic cardiomyopathy.
Cryo-EM structure of a human cytoplasmic actomyosin complex at near-atomic resolution.,von der Ecken J, Heissler SM, Pathan-Chhatbar S, Manstein DJ, Raunser S Nature. 2016 Jun 30;534(7609):724-8. PMID:27324845[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ von der Ecken J, Heissler SM, Pathan-Chhatbar S, Manstein DJ, Raunser S. Cryo-EM structure of a human cytoplasmic actomyosin complex at near-atomic resolution. Nature. 2016 Jun 30;534(7609):724-8. PMID:27324845 doi:http://dx.doi.org/10.1038/nature18295
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