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dc.contributor.authorPrevis, Michael J.
dc.contributor.authorMun, Ji Young
dc.contributor.authorMichalek, Arthur J.
dc.contributor.authorPrevis, Samantha Beck
dc.contributor.authorGulick, James
dc.contributor.authorRobbins, Jeffrey
dc.contributor.authorWarshaw, David M.
dc.contributor.authorCraig, Roger
dc.date2022-08-11T08:08:03.000
dc.date.accessioned2022-08-23T15:40:52Z
dc.date.available2022-08-23T15:40:52Z
dc.date.issued2016-03-22
dc.date.submitted2016-05-31
dc.identifier.citation<p>Proc Natl Acad Sci U S A. 2016 Mar 22;113(12):3239-44. doi: 10.1073/pnas.1522236113. Epub 2016 Feb 23. <a href="http://dx.doi.org/10.1073/pnas.1522236113">Link to article on publisher's site</a></p>
dc.identifier.issn0027-8424 (Linking)
dc.identifier.doi10.1073/pnas.1522236113
dc.identifier.pmid26908872
dc.identifier.urihttp://hdl.handle.net/20.500.14038/26497
dc.description.abstractDuring each heartbeat, cardiac contractility results from calcium-activated sliding of actin thin filaments toward the centers of myosin thick filaments to shorten cellular length. Cardiac myosin-binding protein C (cMyBP-C) is a component of the thick filament that appears to tune these mechanochemical interactions by its N-terminal domains transiently interacting with actin and/or the myosin S2 domain, sensitizing thin filaments to calcium and governing maximal sliding velocity. Both functional mechanisms are potentially further tunable by phosphorylation of an intrinsically disordered, extensible region of cMyBP-C's N terminus, the M-domain. Using atomic force spectroscopy, electron microscopy, and mutant protein expression, we demonstrate that phosphorylation reduced the M-domain's extensibility and shifted the conformation of the N-terminal domain from an extended structure to a compact configuration. In combination with motility assay data, these structural effects of M-domain phosphorylation suggest a mechanism for diminishing the functional potency of individual cMyBP-C molecules. Interestingly, we found that calcium levels necessary to maximally activate the thin filament mitigated the structural effects of phosphorylation by increasing M-domain extensibility and shifting the phosphorylated N-terminal fragments back to the extended state, as if unphosphorylated. Functionally, the addition of calcium to the motility assays ablated the impact of phosphorylation on maximal sliding velocities, fully restoring cMyBP-C's inhibitory capacity. We conclude that M-domain phosphorylation may have its greatest effect on tuning cMyBP-C's calcium-sensitization of thin filaments at the low calcium levels between contractions. Importantly, calcium levels at the peak of contraction would allow cMyBP-C to remain a potent contractile modulator, regardless of cMyBP-C's phosphorylation state.
dc.language.isoen_US
dc.relation<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&list_uids=26908872&dopt=Abstract">Link to Article in PubMed</a>
dc.relation.urlhttp://dx.doi.org/10.1073/pnas.1522236113
dc.rights<p>Publisher PDF posted as allowed by the publisher's author rights policy at http://www.pnas.org/site/aboutpnas/authorfaq.xhtml.</p>
dc.subjectcMyBP-C
dc.subjectmuscle activation
dc.subjectmuscle regulation
dc.subjectstructure-function
dc.subjectBiophysics
dc.subjectCell Biology
dc.titlePhosphorylation and calcium antagonistically tune myosin-binding protein C's structure and function
dc.typeArticle
dc.source.journaltitleProceedings of the National Academy of Sciences of the United States of America
dc.source.volume113
dc.source.issue12
dc.identifier.legacyfulltexthttps://escholarship.umassmed.edu/cgi/viewcontent.cgi?article=1181&amp;context=cellbiology_pp&amp;unstamped=1
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/cellbiology_pp/182
dc.identifier.contextkey8667038
refterms.dateFOA2022-08-23T15:40:52Z
html.description.abstract<p>During each heartbeat, cardiac contractility results from calcium-activated sliding of actin thin filaments toward the centers of myosin thick filaments to shorten cellular length. Cardiac myosin-binding protein C (cMyBP-C) is a component of the thick filament that appears to tune these mechanochemical interactions by its N-terminal domains transiently interacting with actin and/or the myosin S2 domain, sensitizing thin filaments to calcium and governing maximal sliding velocity. Both functional mechanisms are potentially further tunable by phosphorylation of an intrinsically disordered, extensible region of cMyBP-C's N terminus, the M-domain. Using atomic force spectroscopy, electron microscopy, and mutant protein expression, we demonstrate that phosphorylation reduced the M-domain's extensibility and shifted the conformation of the N-terminal domain from an extended structure to a compact configuration. In combination with motility assay data, these structural effects of M-domain phosphorylation suggest a mechanism for diminishing the functional potency of individual cMyBP-C molecules. Interestingly, we found that calcium levels necessary to maximally activate the thin filament mitigated the structural effects of phosphorylation by increasing M-domain extensibility and shifting the phosphorylated N-terminal fragments back to the extended state, as if unphosphorylated. Functionally, the addition of calcium to the motility assays ablated the impact of phosphorylation on maximal sliding velocities, fully restoring cMyBP-C's inhibitory capacity. We conclude that M-domain phosphorylation may have its greatest effect on tuning cMyBP-C's calcium-sensitization of thin filaments at the low calcium levels between contractions. Importantly, calcium levels at the peak of contraction would allow cMyBP-C to remain a potent contractile modulator, regardless of cMyBP-C's phosphorylation state.</p>
dc.identifier.submissionpathcellbiology_pp/182
dc.contributor.departmentDepartment of Cell and Developmental Biology
dc.source.pages3239-44


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