Myosin I mutants with only 1% of wild-type actin-activated MgATPase activity retain essential in vivo function(s)

Proc Natl Acad Sci U S A. 2001 Jul 31;98(16):9122-7. doi: 10.1073/pnas.161285698. Epub 2001 Jul 17.

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.

MeSH terms

  • Actins / metabolism*
  • Aspergillus nidulans / genetics
  • Aspergillus nidulans / metabolism
  • Base Sequence
  • Ca(2+) Mg(2+)-ATPase / metabolism*
  • DNA Primers
  • Enzyme Activation
  • Mutation*
  • Myosins / genetics
  • Myosins / metabolism*
  • Myosins / physiology
  • Phenotype

Substances

  • Actins
  • DNA Primers
  • Ca(2+) Mg(2+)-ATPase
  • Myosins