Stepwise C-Terminal Truncation of Cardiac Troponin T Alters Function at Low and Saturating Ca2
Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved..
Activation of striated muscle contraction occurs in response to Ca2+ binding to troponin C. The resulting reorganization of troponin repositions tropomyosin on actin and permits activation of myosin-catalyzed ATP hydrolysis. It now appears that the C-terminal 14 amino acids of cardiac troponin T (TnT) control the level of activity at both low and high Ca2+. We made a series of C-terminal truncation mutants of human cardiac troponin T, isoform 2, to determine if the same residues of TnT are involved in the low and high Ca2+ effects. We measured the effect of these mutations on the normalized ATPase activity at saturating Ca2+. Changes in acrylodan tropomyosin fluorescence and the degree of Ca2+ stimulation of the rate of binding of rigor myosin subfragment 1 to pyrene-labeled actin-tropomyosin-troponin were measured at low Ca2+. These measurements define the distribution of actin-tropomyosin-troponin among the three regulatory states. Residues SKTR and GRWK of TnT were required for the functioning of TnT at both low and high Ca2+. Thus, the effects on forming the inactive B-state and in retarding formation of the active M-state require the same regions of TnT. We also observed that the rate of binding of rigor subfragment 1 to pyrene-labeled regulated actin at saturating Ca2+ was higher for the truncation mutants than for wild-type TnT. This violated an assumption necessary for determining the B-state population by this kinetic method.
| Medienart: |
E-Artikel |
|---|
| Erscheinungsjahr: |
2018 |
|---|---|
| Erschienen: |
2018 |
| Enthalten in: |
Zur Gesamtaufnahme - volume:115 |
|---|---|
| Enthalten in: |
Biophysical journal - 115(2018), 4 vom: 21. Aug., Seite 702-712 |
| Sprache: |
Englisch |
|---|
| Beteiligte Personen: |
Johnson, Dylan [VerfasserIn] |
|---|
| Links: |
|---|
| Themen: |
8L70Q75FXE |
|---|
| Anmerkungen: |
Date Completed 02.09.2019 Date Revised 09.01.2021 published: Print-Electronic Citation Status MEDLINE |
|---|
| doi: |
10.1016/j.bpj.2018.06.028 |
|---|
| funding: |
|
|---|---|
| Förderinstitution / Projekttitel: |
|
| PPN (Katalog-ID): |
NLM286969335 |
|---|
| LEADER | 01000naa a22002652 4500 | ||
|---|---|---|---|
| 001 | NLM286969335 | ||
| 003 | DE-627 | ||
| 005 | 20231225052942.0 | ||
| 007 | cr uuu---uuuuu | ||
| 008 | 231225s2018 xx |||||o 00| ||eng c | ||
| 024 | 7 | |a 10.1016/j.bpj.2018.06.028 |2 doi | |
| 028 | 5 | 2 | |a pubmed24n0956.xml |
| 035 | |a (DE-627)NLM286969335 | ||
| 035 | |a (NLM)30057009 | ||
| 035 | |a (PII)S0006-3495(18)30775-6 | ||
| 040 | |a DE-627 |b ger |c DE-627 |e rakwb | ||
| 041 | |a eng | ||
| 100 | 1 | |a Johnson, Dylan |e verfasserin |4 aut | |
| 245 | 1 | 0 | |a Stepwise C-Terminal Truncation of Cardiac Troponin T Alters Function at Low and Saturating Ca2 |
| 264 | 1 | |c 2018 | |
| 336 | |a Text |b txt |2 rdacontent | ||
| 337 | |a ƒaComputermedien |b c |2 rdamedia | ||
| 338 | |a ƒa Online-Ressource |b cr |2 rdacarrier | ||
| 500 | |a Date Completed 02.09.2019 | ||
| 500 | |a Date Revised 09.01.2021 | ||
| 500 | |a published: Print-Electronic | ||
| 500 | |a Citation Status MEDLINE | ||
| 520 | |a Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved. | ||
| 520 | |a Activation of striated muscle contraction occurs in response to Ca2+ binding to troponin C. The resulting reorganization of troponin repositions tropomyosin on actin and permits activation of myosin-catalyzed ATP hydrolysis. It now appears that the C-terminal 14 amino acids of cardiac troponin T (TnT) control the level of activity at both low and high Ca2+. We made a series of C-terminal truncation mutants of human cardiac troponin T, isoform 2, to determine if the same residues of TnT are involved in the low and high Ca2+ effects. We measured the effect of these mutations on the normalized ATPase activity at saturating Ca2+. Changes in acrylodan tropomyosin fluorescence and the degree of Ca2+ stimulation of the rate of binding of rigor myosin subfragment 1 to pyrene-labeled actin-tropomyosin-troponin were measured at low Ca2+. These measurements define the distribution of actin-tropomyosin-troponin among the three regulatory states. Residues SKTR and GRWK of TnT were required for the functioning of TnT at both low and high Ca2+. Thus, the effects on forming the inactive B-state and in retarding formation of the active M-state require the same regions of TnT. We also observed that the rate of binding of rigor subfragment 1 to pyrene-labeled regulated actin at saturating Ca2+ was higher for the truncation mutants than for wild-type TnT. This violated an assumption necessary for determining the B-state population by this kinetic method | ||
| 650 | 4 | |a Journal Article | |
| 650 | 7 | |a Actins |2 NLM | |
| 650 | 7 | |a Tropomyosin |2 NLM | |
| 650 | 7 | |a Troponin T |2 NLM | |
| 650 | 7 | |a Adenosine Triphosphate |2 NLM | |
| 650 | 7 | |a 8L70Q75FXE |2 NLM | |
| 650 | 7 | |a Calcium |2 NLM | |
| 650 | 7 | |a SY7Q814VUP |2 NLM | |
| 700 | 1 | |a Angus, C William |e verfasserin |4 aut | |
| 700 | 1 | |a Chalovich, Joseph M |e verfasserin |4 aut | |
| 773 | 0 | 8 | |i Enthalten in |t Biophysical journal |d 1960 |g 115(2018), 4 vom: 21. Aug., Seite 702-712 |w (DE-627)NLM000067571 |x 1542-0086 |7 nnns |
| 773 | 1 | 8 | |g volume:115 |g year:2018 |g number:4 |g day:21 |g month:08 |g pages:702-712 |
| 856 | 4 | 0 | |u http://dx.doi.org/10.1016/j.bpj.2018.06.028 |3 Volltext |
| 912 | |a GBV_USEFLAG_A | ||
| 912 | |a GBV_NLM | ||
| 951 | |a AR | ||
| 952 | |d 115 |j 2018 |e 4 |b 21 |c 08 |h 702-712 | ||