| First Author | Mamidi R | Year | 2013 |
| Journal | FASEB J | Volume | 27 |
| Issue | 9 | Pages | 3848-59 |
| PubMed ID | 23748972 | Mgi Jnum | J:201083 |
| Mgi Id | MGI:5510913 | Doi | 10.1096/fj.13-232363 |
| Citation | Mamidi R, et al. (2013) Interplay between the overlapping ends of tropomyosin and the N terminus of cardiac troponin T affects tropomyosin states on actin. FASEB J 27(9):3848-59 |
| abstractText | The functional significance of the molecular swivel at the head-to-tail overlapping ends of contiguous tropomyosin (Tm) dimers in striated muscle is unknown. Contractile measurements were made in muscle fibers from transgenic (TG) mouse hearts that expressed a mutant alpha-Tm (TmH276N). We also reconstituted mouse cardiac troponin T (McTnT) N-terminal deletion mutants, McTnT1-44Delta and McTnT45-74Delta, into muscle fibers from TmH276N. For controls, we used the wild-type (WT) McTnT because altered effects could be correlated with the mutant forms of McTnT. TmH276N slowed crossbridge (XB) detachment rate (g) by 19%. McTnT1-44Delta attenuated Ca(2+)-activated maximal tension against TmWT (36%) and TmH276N (38%), but sped g only against TmH276N by 35%. The rate of tension redevelopment decreased (17%) only in McTnT1-44Delta + TmH276N fibers. McTnT45-74Delta attenuated tension (19%) and myofilament Ca(2+) sensitivity (pCa50=5.93 vs. 6.00 in the control fibers) against TmH276N, but not against TmWT background. Thus, altered XB cycling kinetics decreased the fraction of strongly bound XBs in McTnT1-44Delta + TmH276N fibers, whereas diminished thin-filament cooperativity attenuated tension in McTnT45-74Delta + TmH276N fibers. In summary, our study is the first to show that the interplay between the N terminus of cTnT and the overlapping ends of contiguous Tm effectuates different states of Tm on the actin filament. -Mamidi, R., Michael, J. J., Muthuchamy, M., Chandra, M. Interplay between the overlapping ends of tropomyosin and the N terminus of cardiac troponin T affects tropomyosin states on actin. |
