期刊
JOURNAL OF MOLECULAR BIOLOGY
卷 400, 期 5, 页码 1036-1045出版社
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmb.2010.06.007
关键词
cardiac troponin I; p21 activated kinase; phosphorylation; Forster resonance energy transfer (FRET); stopped-flow kinetics
资金
- National Institutes of Health [HL80186, HL075643]
- M. J. Murdock Charitable Trust
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 Ca2+, but the detailed mechanism is unknown. We investigated how the structural and kinetic effects mediated by pseudo-phosphorylation of cTnI (S151E) modulates Ca2+-induced activation of cardiac thin filaments. Using steady-state, time-resolved Forster resonance energy transfer (FRET) and stopped-flow kinetic measurements, we monitored Ca2+-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 Ca2+ by shortening the intersite distances between cTnC and cTnI. Furthermore, kinetic rates of Ca2+ 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. (C) 2010 Elsevier Ltd. All rights reserved
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据