title: Polymerization of highly purified Tetrahymena 14-nm filament protein/citrate synthase into filaments and its possible role in regulation of enzymatic activity.
abstract: Tetrahymena 14-nm filament protein (49K protein) is a bifunctional protein with roles in the cytoskeleton and as citrate synthase. Previous studies in our laboratory showed that elongation factor 1 alpha (EF-1 alpha) copurifies with the 49K protein upon polymerization and depolymerization of the 49K protein. In this study, the 49K protein was isolated from partially purified 49K protein fraction containing EF-1 alpha. Using the purified 49K protein and/or purified EF-1 alpha, the interaction between 49K protein and EF-1 alpha in filament formation was investigated electronmicroscopically and it was demonstrated that purified 49K protein was capable of forming 14-nm filaments without EF-1 alpha. The 49K protein/citrate synthase has been suggested to form filaments in mitochondria. Here we show that the citrate synthase activity of 49K protein is decreased by polymerization and increased by depolymerization, suggesting a possible modulating mechanism of citrate synthase activity by monomer-polymer conversion in mitochondria in situ.
authors.affiliation: Institute of Biological Sciences, University of Tsukuba, Ibaraki.
authors.forename: T
authors.initials: T
authors.lastname: Takeda
authors.forename: Y
authors.initials: Y
authors.lastname: Kurasawa
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
authors.forename: O
authors.initials: O
authors.lastname: Numata
mesh_terms: D000818:Animals; D002950:Citrate (si)-Synthase / Q000302:isolation & purification / Q000378:metabolism*; D007381:Intermediate Filament Proteins / Q000302:isolation & purification / Q000378:metabolism*; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors / Q000302:isolation & purification / Q000378:metabolism*; D011108:Polymers / Q000378:metabolism; D015800:Protozoan Proteins / Q000302:isolation & purification / Q000378:metabolism*; D013769:Tetrahymena pyriformis / Q000201:enzymology*
chemical_list: D007381:Intermediate Filament Proteins; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors; D011108:Polymers; D015800:Protozoan Proteins; D002950:Citrate (si)-Synthase