Conformational modulation of slow skeletal muscle troponin T by an NH2-terminal metal-binding extension

Jian Ping Jin, Aihua Chen, Ozgur Ogut, Qi Quan Huang

Research output: Contribution to journalArticle

54 Scopus citations

Abstract

Troponin T (TnT) is an essential element in the thin filament Ca2+-regulatory system controlling striated muscle contraction. Alternative RNA splicing generates developmental and muscle type-specific TnT isoforms differing in the hypervariable NH2-terminal region. Using avian fast skeletal muscle TnT containing a metal-binding segment, we have demonstrated a role of the NH2-terminal domain in modulating the conformation of TnT (Wang J and Jin JP. Biochemistry 37: 14519-14528, 1998). To further investigate the structure-function relationship of TnT, the present study constructed and characterized a recombinant protein in which the metal-binding peptide present in avian fast skeletal muscle TnT was fused to the NH2 terminus of mouse slow skeletal muscle TnT. Metal ion or monoclonal antibody binding to the NH2-terminal extension induced conformational changes in other domains of the model TnT molecule. This was shown by the altered affinity to a monoclonal antibody against the COOH-terminal region and a polyclonal antiserum recognizing multiple epitopes. Protein binding assays showed that metal binding to the NH2-terminal extension had effects on the interaction of TnT with troponin I, troponin C, and most significantly, tropomyosin. The data indicate that the NH2-terminal Tx [4-7 repeats of a sequence motif His-(Glu/Ala)-Glu-Ala-His] extension confers a specific conformational modulation in the slow skeletal muscle TnT.

Original languageEnglish (US)
Pages (from-to)C1067-C1077
JournalAmerican Journal of Physiology - Cell Physiology
Volume279
Issue number4 48-4
StatePublished - Dec 7 2000

Keywords

  • ELISA protein binding assay
  • Epitope analysis
  • Metal affinity chromatography
  • Thin filament

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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