title: Myosin I mutants with only 1% of wild-type actin-activated MgATPase activity retain essential in vivo function(s).
abstract: The single class I myosin (MYOA) of Aspergillus nidulans is essential for hyphal growth. It is generally assumed that the functions of all myosins depend on their actin-activated MgATPase activity. Here we show that MYOA mutants with no more than 1% of the actin-activated MgATPase activity of wild-type MYOA in vitro and no detectable in vitro motility activity can support fungal cell growth, albeit with a delay in germination time and a reduction in hyphal elongation. From these and other data, we conclude that the essential role(s) of myosin I in A. nidulans is probably structural, requiring little, if any, actin-activated MgATPase or motor activity, which have long been considered the defining characteristics of the myosin family.
authors.affiliation: Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 50, Room 2517, Bethesda, MD 20892, USA.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.forename: N
authors.initials: N
authors.lastname: Osherov
authors.forename: R
authors.initials: R
authors.lastname: Yamashita
authors.forename: H
authors.initials: H
authors.lastname: Brzeska
authors.forename: E D
authors.initials: ED
authors.lastname: Korn
authors.forename: G S
authors.initials: GS
authors.lastname: May
mesh_terms: D000199:Actins / Q000378:metabolism*; D001233:Aspergillus nidulans / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D017931:DNA Primers; D004789:Enzyme Activation; D009154:Mutation; D009218:Myosins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D010641:Phenotype
chemical_list: D000199:Actins; D017931:DNA Primers; D017301:Ca(2+) Mg(2+)-ATPase; D009218:Myosins