Myosin I mutants with only 1% of wild-type actin-activated MgATPase activity retain essential in vivo function(s).
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.
Liu
X
X
Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 50, Room 2517, Bethesda, MD 20892, USA.
Osherov
N
N
Yamashita
R
R
Brzeska
H
H
Korn
E D
ED
May
G S
GS
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
D000199:Actins; D017931:DNA Primers; D017301:Ca(2+) Mg(2+)-ATPase; D009218:Myosins