Yeast mitochondria contain ATP-sensitive, reversible actin-binding activity.
Sedimentation assays were used to demonstrate and characterize binding of isolated yeast mitochondria to phalloidin-stabilized yeast F-actin. These actin-mitochondrial interactions are ATP sensitive, saturable, reversible, and do not depend upon mitochondrial membrane potential. Protease digestion of mitochondrial outer membrane proteins or saturation of myosin-binding sites on F-actin with the S1 subfragment of skeletal myosin block binding. These observations indicate that a protein (or proteins) on the mitochondrial surface mediates ATP-sensitive, reversible binding of mitochondria to the lateral surface of microfilaments. Actin copurifies with mitochondria during subcellular fractionation and is released from the organelle upon treatment with ATP. Thus, actin-mitochondrial interactions resembling those observed in vitro may also exist in intact yeast cells. Finally, a yeast mutant bearing a temperature-sensitive mutation in the actin-encoding ACT1 gene (act1-3) displays temperature-dependent defects in transfer of mitochondria from mother cells to newly developed buds during yeast cell mitosis.
Lazzarino
D A
DA
Department of Anatomy and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York 10032.
Boldogh
I
I
Smith
M G
MG
Rosand
J
J
Pon
L A
LA
D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D005656:Fungal Proteins / Q000378:metabolism*; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism; D017354:Point Mutation; D011485:Protein Binding / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D014461:Ultracentrifugation
D000199:Actins; D005656:Fungal Proteins; D008840:Microfilament Proteins; D000255:Adenosine Triphosphate; D009218:Myosins