Structural and Kinetic Effects of PAK3 Phosphorylation Mimic of cTnI(S151E) on the cTnC-cTnI Interaction in the Cardiac Thin Filament

Yexin Ouyang; Ranganath Mamidi; Jayant James Jayasundar; Murali Chandra; Wen-Ji Dong

doi:10.1016/j.jmb.2010.06.007

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Structural and Kinetic Effects of PAK3 Phosphorylation Mimic of cTnI(S151E) on the cTnC-cTnI Interaction in the Cardiac Thin Filament

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Structural and Kinetic Effects of PAK3 Phosphorylation Mimic of cTnI(S151E) on the cTnC-cTnI Interaction in the Cardiac Thin Filament

Yexin Ouyang, Ranganath Mamidi, Jayant James Jayasundar, Murali Chandra and Wen-Ji Dong

Journal of molecular biology, Vol.400(5), pp.1036-1045

2010

DOI: https://doi.org/10.1016/j.jmb.2010.06.007

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https://hdl.handle.net/2376/107052

PMCID: PMC2911129

PMID: 20540949

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https://doi.org/10.1016/j.jmb.2010.06.007View

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Abstract

stopped-flow kinetics

p21 activated kinase

phosphorylation

Förster resonance energy transfer (FRET)

cardiac troponin I

Residue Ser151 of cardiac troponin I (cTnI) is known to be phosphorylated by p21-activated kinase 3 (PAK3). It has been found that PAK3-mediated phosphorylation of cTnI induces an increase in the sensitivity of myofilament to Ca 2+, but the detailed mechanism is unknown. We investigated how the structural and kinetic effects mediated by pseudo-phosphorylation of cTnI (S151E) modulates Ca 2+-induced activation of cardiac thin filaments. Using steady-state, time-resolved Förster resonance energy transfer (FRET) and stopped-flow kinetic measurements, we monitored Ca 2+-induced changes in cTnI–cTnC interactions. Measurements were done using reconstituted thin filaments, which contained the pseudo-phosphorylated cTnI(S151E). We hypothesized that the thin filament regulation is modulated by altered cTnC–cTnI interactions due to charge modification caused by the phosphorylation of Ser151 in cTnI. Our results showed that the pseudo-phosphorylation of cTnI (S151E) sensitizes structural changes to Ca 2+ by shortening the intersite distances between cTnC and cTnI. Furthermore, kinetic rates of Ca 2+ dissociation-induced structural change in the regulatory region of cTnI were reduced significantly by cTnI (S151E). The aforementioned effects of pseudo-phosphorylation of cTnI were similar to those of strong crossbridges on structural changes in cTnI. Our results provide novel information on how cardiac thin filament regulation is modulated by PAK3 phosphorylation of cTnI.

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Title: Structural and Kinetic Effects of PAK3 Phosphorylation Mimic of cTnI(S151E) on the cTnC-cTnI Interaction in the Cardiac Thin Filament
Creators: Yexin Ouyang - Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
Ranganath Mamidi - Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, WA 99164, USA
Jayant James Jayasundar - Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
Murali Chandra - Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, WA 99164, USA
Wen-Ji Dong - Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
Publication Details: Journal of molecular biology, Vol.400(5), pp.1036-1045
Academic Unit: Integrative Physiology and Neuroscience, Department of; Chemical Engineering and Bioengineering, School of
Publisher: Elsevier Ltd
Identifiers: 99900546810701842
Language: English
Resource Type: Journal article