title: Impact of actin glutathionylation on the actomyosin-S1 ATPase.
abstract: Glutathionylation of intracellular proteins is an established physiological regulator of protein function. In multiple models, including ischemia-reperfusion of the heart, increased oxidative stress results in the glutathionylation of sarcomeric actin. We hypothesized that actin glutathionylation may play a role in the multifactorial change in cardiac muscle contractility observed during this pathophysiological state. Therefore, the functional impact of glutathionylated actin on the interaction with myosin-S1 was examined. Substituting glutathionylated F-actin for unmodified F-actin reduced the maximum actomyosin-S1 ATPase, and this was accompanied by an increase in the activation energy of the steady state ATPase. Measurement of steady state binding did not suggest a large impact of actin glutathionylation on the binding to myosin-S1. However, transient binding and dissociation kinetics determined by stopped-flow methods demonstrated that although actin glutathionylation did not significantly alter the rate constant of myosin-S1 binding, there was a significant decrease in the rate of ATP-induced myosin-S1 detachment in the presence of ADP. These results suggest that actin glutathionylation may play a limited but defined role in the alteration of contractility following oxidative stress to the myocardium, particularly through a decrease in the actomyosin ATPase activity.
authors: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55902, USA.
authors: Gresin O
authors: GO
authors: Pizarro
authors: Ozgur
authors: O
authors: Ogut
mesh_terms: D000199:Actins / Q000737:chemistry* / Q000502:physiology; D000205:Actomyosin / Q000737:chemistry / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D005978:Glutathione / Q000737:chemistry / Q000378:metabolism*; D009200:Myocardial Contraction; D015879:Myosin Subfragments / Q000737:chemistry / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology; D011485:Protein Binding; D011817:Rabbits; D014335:Tropomyosin / Q000378:metabolism
chemical_list: D000199:Actins; D015879:Myosin Subfragments; D014335:Tropomyosin; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000205:Actomyosin; D005978:Glutathione