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dc.contributor.authorAlamo, Lorenzo
dc.contributor.authorWriggers, Willy
dc.contributor.authorPinto, Antonio
dc.contributor.authorBartoli, Fulvia
dc.contributor.authorSalazar, Leiria
dc.contributor.authorZhao, Fa-Qing
dc.contributor.authorCraig, Roger W.
dc.contributor.authorPadron, Raul
dc.date2022-08-11T08:08:12.000
dc.date.accessioned2022-08-23T15:46:06Z
dc.date.available2022-08-23T15:46:06Z
dc.date.issued2008-10-28
dc.date.submitted2010-10-06
dc.identifier.citationJ Mol Biol. 2008 Dec 26;384(4):780-97. Epub 2008 Oct 14. <a href="http://dx.doi.org/10.1016/j.jmb.2008.10.013">Link to article on publisher's site</a>
dc.identifier.issn0022-2836 (Linking)
dc.identifier.doi10.1016/j.jmb.2008.10.013
dc.identifier.pmid18951904
dc.identifier.urihttp://hdl.handle.net/20.500.14038/27681
dc.description.abstractMuscle contraction involves the interaction of the myosin heads of the thick filaments with actin subunits of the thin filaments. Relaxation occurs when this interaction is blocked by molecular switches on these filaments. In many muscles, myosin-linked regulation involves phosphorylation of the myosin regulatory light chains (RLCs). Electron microscopy of vertebrate smooth muscle myosin molecules (regulated by phosphorylation) has provided insight into the relaxed structure, revealing that myosin is switched off by intramolecular interactions between its two heads, the free head and the blocked head. Three-dimensional reconstruction of frozen-hydrated specimens revealed that this asymmetric head interaction is also present in native thick filaments of tarantula striated muscle. Our goal in this study was to elucidate the structural features of the tarantula filament involved in phosphorylation-based regulation. A new reconstruction revealed intra- and intermolecular myosin interactions in addition to those seen previously. To help interpret the interactions, we sequenced the tarantula RLC and fitted an atomic model of the myosin head that included the predicted RLC atomic structure and an S2 (subfragment 2) crystal structure to the reconstruction. The fitting suggests one intramolecular interaction, between the cardiomyopathy loop of the free head and its own S2, and two intermolecular interactions, between the cardiac loop of the free head and the essential light chain of the blocked head and between the Leu305-Gln327 interaction loop of the free head and the N-terminal fragment of the RLC of the blocked head. These interactions, added to those previously described, would help switch off the thick filament. Molecular dynamics simulations suggest how phosphorylation could increase the helical content of the RLC N-terminus, weakening these interactions, thus releasing both heads and activating the thick filament.
dc.language.isoen_US
dc.relation<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&list_uids=18951904&dopt=Abstract">Link to Article in PubMed</a>
dc.relation.urlhttp://dx.doi.org/10.1016/j.jmb.2008.10.013
dc.subjectAnimals
dc.subjectCrystallography, X-Ray
dc.subjectMicroscopy, Electron, Transmission
dc.subjectModels, Molecular
dc.subjectMolecular Sequence Data
dc.subjectMyosin Light Chains
dc.subjectMyosins
dc.subjectPhosphorylation
dc.subjectProtein Structure, Quaternary
dc.subjectProtein Structure, Secondary
dc.subjectProtein Structure, Tertiary
dc.subjectSequence Analysis, DNA
dc.subjectSpiders
dc.subjectCell Biology
dc.titleThree-dimensional reconstruction of tarantula myosin filaments suggests how phosphorylation may regulate myosin activity
dc.typeArticle
dc.source.journaltitleJournal of molecular biology
dc.source.volume384
dc.source.issue4
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/craig/6
dc.identifier.contextkey1594905
html.description.abstract<p>Muscle contraction involves the interaction of the myosin heads of the thick filaments with actin subunits of the thin filaments. Relaxation occurs when this interaction is blocked by molecular switches on these filaments. In many muscles, myosin-linked regulation involves phosphorylation of the myosin regulatory light chains (RLCs). Electron microscopy of vertebrate smooth muscle myosin molecules (regulated by phosphorylation) has provided insight into the relaxed structure, revealing that myosin is switched off by intramolecular interactions between its two heads, the free head and the blocked head. Three-dimensional reconstruction of frozen-hydrated specimens revealed that this asymmetric head interaction is also present in native thick filaments of tarantula striated muscle. Our goal in this study was to elucidate the structural features of the tarantula filament involved in phosphorylation-based regulation. A new reconstruction revealed intra- and intermolecular myosin interactions in addition to those seen previously. To help interpret the interactions, we sequenced the tarantula RLC and fitted an atomic model of the myosin head that included the predicted RLC atomic structure and an S2 (subfragment 2) crystal structure to the reconstruction. The fitting suggests one intramolecular interaction, between the cardiomyopathy loop of the free head and its own S2, and two intermolecular interactions, between the cardiac loop of the free head and the essential light chain of the blocked head and between the Leu305-Gln327 interaction loop of the free head and the N-terminal fragment of the RLC of the blocked head. These interactions, added to those previously described, would help switch off the thick filament. Molecular dynamics simulations suggest how phosphorylation could increase the helical content of the RLC N-terminus, weakening these interactions, thus releasing both heads and activating the thick filament.</p>
dc.identifier.submissionpathcraig/6
dc.contributor.departmentDepartment of Cell Biology
dc.source.pages780-97


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