title: Mammalian Nonmuscle Myosin II Binds to Anionic Phospholipids with Concomitant Dissociation of the Regulatory Light Chain.
abstract: Mammalian cells express three Class II nonmuscle myosins (NM): NM2A, NM2B, and NM2C. The three NM2s have well established essential roles in cell motility, adhesion, and cytokinesis and less well defined roles in vesicle transport and other processes that would require association of NM2s with cell membranes. Previous evidence for the mechanism of NM2-membrane association includes direct interaction of NM2s with membrane lipids and indirect interaction by association of NM2s with membrane-bound F-actin or peripheral membrane proteins. Direct binding of NM2s to phosphatidylserine-liposomes, but not to phosphatidylcholine-liposomes, has been reported, but the molecular basis of the interaction between NM2s and acidic phospholipids has not been previously investigated. We now show that filamentous, full-length NM2A, NM2B, and NM2C and monomeric, non-filamentous heavy meromyosin bind to liposomes containing one or more acidic phospholipids (phosphatidylserine, phosphatidylinositol 4,5-diphosphate, and phosphatidylinositol 3,4,5-triphosphate) but do not bind to 100% phosphatidylcholine-liposomes. Binding of NM2s to acidic liposomes occurs predominantly through interaction of the liposomes with the regulatory light chain (RLC) binding site in the myosin heavy chain with concomitant dissociation of the RLC. Phosphorylation of myosin-bound RLC by myosin light chain kinase substantially inhibits binding to liposomes of both filamentous NM2 and non-filamentous heavy meromyosin; the addition of excess unbound RLC, but not excess unbound essential light chain, competes with liposome binding. Consistent with the in vitro data, we show that endogenous and expressed NM2A associates with the plasma membrane of HeLa cells and fibrosarcoma cells independently of F-actin.
authors.affiliation: From the Laboratories of Cell Biology and.
authors.forename: Xiong
authors.initials: X
authors.lastname: Liu
authors.affiliation: From the Laboratories of Cell Biology and.
authors.forename: Shi
authors.initials: S
authors.lastname: Shu
authors.affiliation: Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892-1583.
authors.forename: Neil
authors.initials: N
authors.lastname: Billington
authors.affiliation: From the Laboratories of Cell Biology and.
authors.forename: Chad D
authors.initials: CD
authors.lastname: Williamson
authors.affiliation: From the Laboratories of Cell Biology and.
authors.forename: Shuhua
authors.initials: S
authors.lastname: Yu
authors.affiliation: From the Laboratories of Cell Biology and.
authors.forename: Hanna
authors.initials: H
authors.lastname: Brzeska
authors.affiliation: From the Laboratories of Cell Biology and.
authors.forename: Julie G
authors.initials: JG
authors.lastname: Donaldson
authors.affiliation: Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892-1583.
authors.forename: James R
authors.initials: JR
authors.lastname: Sellers
authors.affiliation: From the Laboratories of Cell Biology and edk@nih.gov.
authors.forename: Edward D
authors.initials: ED
authors.lastname: Korn
mesh_terms: D000199:Actins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008081:Liposomes / Q000737:chemistry; D018994:Myosin Light Chains / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024462:Myosin Type II / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000199:Actins; D008081:Liposomes; D018994:Myosin Light Chains; D010743:Phospholipids; D024462:Myosin Type II
keywords: cell biology; cell motility; lipid-binding protein; liposome; myosin; phosphatidylserine