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...
Main Authors: | , , , |
---|---|
Format: | Journal article |
Language: | English |
Published: |
2009
|
_version_ | 1797053950199857152 |
---|---|
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. |
first_indexed | 2024-03-06T18:50:45Z |
format | Journal article |
id | oxford-uuid:10217f58-b5b0-4f03-b741-a619d75ab78e |
institution | University of Oxford |
language | English |
last_indexed | 2024-03-06T18:50:45Z |
publishDate | 2009 |
record_format | dspace |
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 |
work_keys_str_mv | AT borovikovy modulationoftheeffectsoftropomyosinonactinandmyosinconformationalchangesbytroponinandca2 AT karpichevao modulationoftheeffectsoftropomyosinonactinandmyosinconformationalchangesbytroponinandca2 AT avrovas modulationoftheeffectsoftropomyosinonactinandmyosinconformationalchangesbytroponinandca2 AT redwoodc modulationoftheeffectsoftropomyosinonactinandmyosinconformationalchangesbytroponinandca2 |