Show simple item record

dc.contributor.authorLi, Xiang-Dong
dc.contributor.authorRhodes, Troy E.
dc.contributor.authorIkebe, Reiko
dc.contributor.authorKambara, Taketoshi
dc.contributor.authorWhite, Howard D.
dc.contributor.authorIkebe, Mitsuo
dc.date2022-08-11T08:10:04.000
dc.date.accessioned2022-08-23T16:54:06Z
dc.date.available2022-08-23T16:54:06Z
dc.date.issued1998-10-09
dc.date.submitted2008-08-04
dc.identifier.citation<p>J Biol Chem. 1998 Oct 16;273(42):27404-11.</p>
dc.identifier.issn0021-9258 (Print)
dc.identifier.doi10.1074/jbc.273.42.27404
dc.identifier.pmid9765269
dc.identifier.urihttp://hdl.handle.net/20.500.14038/42423
dc.description.abstractThe role of the highly conserved residues in the gamma-phosphate binding site of myosin upon myosin motor function was studied. Each of five residues (Ser181, Lys185, Asn235, Ser236, and Arg238) in smooth muscle myosin was mutated. K185Q has neither a steady state ATPase nor an initial Pi burst. Although ATP and actin bind to K185Q, it is not dissociated from actin by ATP. These results indicate that the hydrolysis of bound ATP by K185Q is inhibited. S236T has nearly normal basal Mg2+-ATPase activity, initial Pi burst, ATP-induced enhancement of intrinsic tryptophan fluorescence, and ATP-induced dissociation from actin. However, the actin activation of the Mg2+-ATPase activity and actin translocation of S236T were blocked. In contrast S236A has nearly normal enzymatic properties and actin-translocating activity. These results indicate that 1) the hydroxyl group of Ser236 is not critical as an intermediary of proton transfer during the ATP hydrolysis step, and 2) the bulk of the extra methyl group of the threonine residue in S236T blocks the acceleration of product release from the active site by actin. Arg238, which interacts with Glu459 at the Switch II region, was mutated to Lys and Ile, respectively. R238K has essentially normal enzymatic activity and motility. In contrast, R238I does not hydrolyze ATP or support motility, although it still binds ATP. These results indicate that the charge interaction between Glu459 and Arg238 is critical for ATP hydrolysis by myosin. Other mutants, S181A, S181T, and N235I, showed nearly normal enzymatic and motile activity.
dc.language.isoen_US
dc.relation<p><a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&list_uids=9765269&dopt=Abstract">Link to Article in PubMed</a></p>
dc.relation.urlhttps://doi.org/10.1074/jbc.273.42.27404
dc.subjectActins
dc.subjectAdenosine Diphosphate
dc.subjectAdenosine Triphosphate
dc.subjectBinding Sites
dc.subjectCatalytic Domain
dc.subjectFlow Injection Analysis
dc.subjectHydrolysis
dc.subjectModels, Chemical
dc.subjectModels, Molecular
dc.subject*Motion
dc.subjectMuscle, Smooth
dc.subjectMutation
dc.subjectMyosins
dc.subjectProtein Binding
dc.subjectRecombinant Proteins
dc.subjectLife Sciences
dc.subjectMedicine and Health Sciences
dc.titleEffects of mutations in the gamma-phosphate binding site of myosin on its motor function
dc.typeJournal Article
dc.source.journaltitleThe Journal of biological chemistry
dc.source.volume273
dc.source.issue42
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/oapubs/774
dc.identifier.contextkey564689
html.description.abstract<p>The role of the highly conserved residues in the gamma-phosphate binding site of myosin upon myosin motor function was studied. Each of five residues (Ser181, Lys185, Asn235, Ser236, and Arg238) in smooth muscle myosin was mutated. K185Q has neither a steady state ATPase nor an initial Pi burst. Although ATP and actin bind to K185Q, it is not dissociated from actin by ATP. These results indicate that the hydrolysis of bound ATP by K185Q is inhibited. S236T has nearly normal basal Mg2+-ATPase activity, initial Pi burst, ATP-induced enhancement of intrinsic tryptophan fluorescence, and ATP-induced dissociation from actin. However, the actin activation of the Mg2+-ATPase activity and actin translocation of S236T were blocked. In contrast S236A has nearly normal enzymatic properties and actin-translocating activity. These results indicate that 1) the hydroxyl group of Ser236 is not critical as an intermediary of proton transfer during the ATP hydrolysis step, and 2) the bulk of the extra methyl group of the threonine residue in S236T blocks the acceleration of product release from the active site by actin. Arg238, which interacts with Glu459 at the Switch II region, was mutated to Lys and Ile, respectively. R238K has essentially normal enzymatic activity and motility. In contrast, R238I does not hydrolyze ATP or support motility, although it still binds ATP. These results indicate that the charge interaction between Glu459 and Arg238 is critical for ATP hydrolysis by myosin. Other mutants, S181A, S181T, and N235I, showed nearly normal enzymatic and motile activity.</p>
dc.identifier.submissionpathoapubs/774
dc.contributor.departmentDepartment of Physiology
dc.source.pages27404-11


This item appears in the following Collection(s)

Show simple item record