Tropomyosins, a family of actin-binding regulatory proteins, are present in muscle and non-muscle cells. Multiple tropomyosin (TM) isoforms differ in actin affinity and regulatory properties, but little is known about the molecular bases of these differences. The C-terminus of actin stabilizes contacts between actin subunits in the filament and interacts with myosin and regulatory proteins. The goal of this work was to reveal how structural changes in actin and differences between TM isoforms affect binding between these proteins and affect thin filament regulation. Actin proteolytically truncated by three C-terminal amino acids exhibited 1.2-1.5 fold reduced affinity for non-muscle and smooth muscle tropomyosin isoforms. The truncation increased the cooperativity of myosin S1-induced tropomyosin binding for short tropomyosins (TM5a and TM1b9a), but it was neutral for long isoforms (smTM and TM2). Actin modification affected regulation of actomyosin ATPase activity in the presence of all tropomyosins by shifting the filament into a more active state. We conclude that the integrity of the actin C-terminus is important for actin-tropomyosin interactions, however the increased affinity of tropomyosin binding in the S1-induced state of the filament appears not to be involved in the tropomyrosin isoform-dependent mechanism of the actomyosin ATPase activation. (C) 2008 Elsevier B.V. All rights reserved.
机构:
Kazimierz Wielki Univ, Fac Nat Sci, Dept Biochem & Cell Biol, Bydgoszcz, Poland
Univ Calif Los Angeles, Dept Chem & Biochem, 405 Hilgard Ave, Los Angeles, CA 90024 USAKazimierz Wielki Univ, Fac Nat Sci, Dept Biochem & Cell Biol, Bydgoszcz, Poland
Ostrowska-Podhorodecka, Zofia
Sliwinska, Malgorzata
论文数: 0引用数: 0
h-index: 0
机构:
Kazimierz Wielki Univ, Fac Nat Sci, Dept Biochem & Cell Biol, Bydgoszcz, PolandKazimierz Wielki Univ, Fac Nat Sci, Dept Biochem & Cell Biol, Bydgoszcz, Poland
Sliwinska, Malgorzata
Reisler, Emil
论文数: 0引用数: 0
h-index: 0
机构:
Univ Calif Los Angeles, Dept Chem & Biochem, 405 Hilgard Ave, Los Angeles, CA 90024 USA
Univ Calif Los Angeles, Dept Mol Biol Inst, Los Angeles, CA USAKazimierz Wielki Univ, Fac Nat Sci, Dept Biochem & Cell Biol, Bydgoszcz, Poland
Reisler, Emil
Moraczewska, Joanna
论文数: 0引用数: 0
h-index: 0
机构:
Kazimierz Wielki Univ, Fac Nat Sci, Dept Biochem & Cell Biol, Bydgoszcz, PolandKazimierz Wielki Univ, Fac Nat Sci, Dept Biochem & Cell Biol, Bydgoszcz, Poland
机构:
Univ Med & Dent New Jersey, Robert Wood Johnson Med Sch, Piscataway, NJ 08854 USAUniv Med & Dent New Jersey, Robert Wood Johnson Med Sch, Piscataway, NJ 08854 USA
Kostyukova, AS
Rapp, B
论文数: 0引用数: 0
h-index: 0
机构:
Univ Med & Dent New Jersey, Robert Wood Johnson Med Sch, Piscataway, NJ 08854 USAUniv Med & Dent New Jersey, Robert Wood Johnson Med Sch, Piscataway, NJ 08854 USA
Rapp, B
Choy, A
论文数: 0引用数: 0
h-index: 0
机构:
Univ Med & Dent New Jersey, Robert Wood Johnson Med Sch, Piscataway, NJ 08854 USAUniv Med & Dent New Jersey, Robert Wood Johnson Med Sch, Piscataway, NJ 08854 USA
Choy, A
Greenfield, NJ
论文数: 0引用数: 0
h-index: 0
机构:
Univ Med & Dent New Jersey, Robert Wood Johnson Med Sch, Piscataway, NJ 08854 USAUniv Med & Dent New Jersey, Robert Wood Johnson Med Sch, Piscataway, NJ 08854 USA
Greenfield, NJ
Hitchcock-Degregori, SE
论文数: 0引用数: 0
h-index: 0
机构:
Univ Med & Dent New Jersey, Robert Wood Johnson Med Sch, Piscataway, NJ 08854 USAUniv Med & Dent New Jersey, Robert Wood Johnson Med Sch, Piscataway, NJ 08854 USA