Modulation of the effects of tropomyosin on actin and myosin conformational changes by troponin and Ca2+.

The molecular mechanisms by which troponin (TN)-tropomyosin (TM) regulates the myosin ATPase cycle were investigated using fluorescent probes specifically bound to Cys36 of TM, Cys707 of myosin subfragment-1, and Cys374 of actin incorporated into ghost muscle fibers. Intermediate states of actomyosi...

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Main Authors: Borovikov, Y, Karpicheva, O, Avrova, S, Redwood, C
Format: Journal article
Language:English
Published: 2009
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author Borovikov, Y
Karpicheva, O
Avrova, S
Redwood, C
author_facet Borovikov, Y
Karpicheva, O
Avrova, S
Redwood, C
author_sort Borovikov, Y
collection OXFORD
description The molecular mechanisms by which troponin (TN)-tropomyosin (TM) regulates the myosin ATPase cycle were investigated using fluorescent probes specifically bound to Cys36 of TM, Cys707 of myosin subfragment-1, and Cys374 of actin incorporated into ghost muscle fibers. Intermediate states of actomyosin were simulated by using nucleotides and non-hydrolysable ATP analogs. Multistep changes in mobility and spatial arrangement of SH1 helix of myosin motor domain and actin subdomain-1 during the ATPase cycle were observed. Each intermediate state of actomyosin induced a definite conformational state and specific position of TM strands on the surface of thin filament. TM increased the amplitude of myosin SH1 helix and actin subdomain-1 movements at transition from weak- to strong-binding states shifting to the center of thin filament at strong-binding and to the periphery of thin filament at weak-binding states. TN modulated those movements in a capital ES, Cyrillicsmall a, Cyrillic(2+)-dependent manner. At high-Ca(2+), TN enhanced the effect of TM on SH1 helix and subdomain-1 movements by transferring TM further to the center of thin filament at strong-binding states. In contrast, at low-Ca(2+), TN inhibited the effect of TM movements, "freezing" actin structure in "OFF" state and TM in the position typical for weak-binding states, resulting in disturbing the interplay of actin and myosin.
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spelling oxford-uuid:10217f58-b5b0-4f03-b741-a619d75ab78e2022-03-26T09:54:51ZModulation of the effects of tropomyosin on actin and myosin conformational changes by troponin and Ca2+.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:10217f58-b5b0-4f03-b741-a619d75ab78eEnglishSymplectic Elements at Oxford2009Borovikov, YKarpicheva, OAvrova, SRedwood, CThe molecular mechanisms by which troponin (TN)-tropomyosin (TM) regulates the myosin ATPase cycle were investigated using fluorescent probes specifically bound to Cys36 of TM, Cys707 of myosin subfragment-1, and Cys374 of actin incorporated into ghost muscle fibers. Intermediate states of actomyosin were simulated by using nucleotides and non-hydrolysable ATP analogs. Multistep changes in mobility and spatial arrangement of SH1 helix of myosin motor domain and actin subdomain-1 during the ATPase cycle were observed. Each intermediate state of actomyosin induced a definite conformational state and specific position of TM strands on the surface of thin filament. TM increased the amplitude of myosin SH1 helix and actin subdomain-1 movements at transition from weak- to strong-binding states shifting to the center of thin filament at strong-binding and to the periphery of thin filament at weak-binding states. TN modulated those movements in a capital ES, Cyrillicsmall a, Cyrillic(2+)-dependent manner. At high-Ca(2+), TN enhanced the effect of TM on SH1 helix and subdomain-1 movements by transferring TM further to the center of thin filament at strong-binding states. In contrast, at low-Ca(2+), TN inhibited the effect of TM movements, "freezing" actin structure in "OFF" state and TM in the position typical for weak-binding states, resulting in disturbing the interplay of actin and myosin.
spellingShingle Borovikov, Y
Karpicheva, O
Avrova, S
Redwood, C
Modulation of the effects of tropomyosin on actin and myosin conformational changes by troponin and Ca2+.
title Modulation of the effects of tropomyosin on actin and myosin conformational changes by troponin and Ca2+.
title_full Modulation of the effects of tropomyosin on actin and myosin conformational changes by troponin and Ca2+.
title_fullStr Modulation of the effects of tropomyosin on actin and myosin conformational changes by troponin and Ca2+.
title_full_unstemmed Modulation of the effects of tropomyosin on actin and myosin conformational changes by troponin and Ca2+.
title_short Modulation of the effects of tropomyosin on actin and myosin conformational changes by troponin and Ca2+.
title_sort modulation of the effects of tropomyosin on actin and myosin conformational changes by troponin and ca2
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AT karpichevao modulationoftheeffectsoftropomyosinonactinandmyosinconformationalchangesbytroponinandca2
AT avrovas modulationoftheeffectsoftropomyosinonactinandmyosinconformationalchangesbytroponinandca2
AT redwoodc modulationoftheeffectsoftropomyosinonactinandmyosinconformationalchangesbytroponinandca2