Trimethylamine N-oxide suppresses the activity of the actomyosin motor

• Published in: Biochimica et biophysica acta Vol. 1820; no. 10; pp. 1597 - 1604
• Main Authors: Kumemoto, Ryusei, Yusa, Kento, Shibayama, Tomohiro, Hatori, Kuniyuki
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2012
• Subjects: actin; Actin Cytoskeleton - chemistry; Actin Cytoskeleton - drug effects; Actin Cytoskeleton - metabolism; Actomyosin - antagonists & inhibitors; Actomyosin - chemistry; Actomyosin - metabolism; Adenosine Triphosphatases - metabolism; adenosine triphosphate; adenosinetriphosphatase; Animals; ATP hydrolysis; ATPase; circular dichroism spectroscopy; Dose-Response Relationship, Drug; Down-Regulation - drug effects; energy; fluorescence; heavy meromyosin; Hydration; hydrogen bonding; hydrolysis; In Vitro Techniques; malachite green; Methylamines - pharmacology; microfilaments; Motility; Movement - drug effects; Multiprotein Complexes - chemistry; Multiprotein Complexes - metabolism; Muscular protein; Myosin Subfragments - chemistry; Myosin Subfragments - metabolism; Osmolar Concentration; Osmolyte; Protein Stability - drug effects; Rabbits; skeletal muscle; trimethylamine; Urea; Urea - pharmacology; water stress; TMAO; Motility; ATP hydrolysis; Hydration; HMM; Muscular protein; PCA; BSA; Urea; Pi; bis-ANS; Osmolyte; ATP
• DOI: 10.1016/j.bbagen.2012.06.006
• ISSN: 0304-4165; 0006-3002

During actomyosin interactions, the transduction of energy from ATP hydrolysis to motility seems to occur with the modulation of hydration. Trimethylamine N-oxide (TMAO) perturbs the surface of proteins by altering hydrogen bonding in a manner opposite to that of urea. Hence, we focus on the effects of TMAO on the motility and ATPase activation of actomyosin complexes. Actin and heavy meromyosin (HMM) were prepared from rabbit skeletal muscle. Structural changes in HMM were detected using fluorescence and circular dichroism spectroscopy. The sliding velocity of rhodamine-phalloidin-bound actin filaments on HMM was measured using an in vitro motility assay. ATPase activity was measured using a malachite green method. Although TMAO, unlike urea, stabilized the HMM structure, both the sliding velocity and ATPase activity of acto-HMM were considerably decreased with increasing TMAO concentrations from 0–1.0M. Whereas urea-induced decreases in the structural stability of HMM were recovered by TMAO, TMAO further decreased the urea-induced decrease in ATPase activation. Urea and TMAO were found to have counteractive effects on motility at concentrations of 0.6M and 0.2M, respectively. The excessive stabilization of the HMM structure by TMAO may suppress its activities; however, the counteractive effects of urea and TMAO on actomyosin motor activity is distinct from their effects on HMM stability. The present results provide insight into not only the water-related properties of proteins, but also the physiological significance of TMAO and urea osmolytes in the muscular proteins of water-stressed animals. ► TMAO stabilized the actomyosin structure. ► TMAO and urea decreased the motility and ATPase activation of actomyosin. ► TMAO counteracts the effects of urea on motility but not ATPase activation.