Yeast myosin light chain, Mlc1p, interacts with both IQGAP and class II myosin to effect cytokinesis.
MLC1 (myosin light chain) acts as a dosage suppressor of a temperature sensitive mutation in the gene encoding the S. cerevisiae IQGAP protein. Both proteins localize to the bud neck in mitosis although Mlc1p localisation precedes Iqg1p. Mlc1p is also found at the incipient bud site in G(1) and the growing bud tip during S and G(2) phases of the cell cycle. A dominant negative GST-Mlc1p fusion protein specifically blocks cytokinesis and prevents Iqg1p localisation to the bud neck, as does depletion of Mlc1p. These data support a direct interaction between the two proteins and immunoprecipitation experiments confirm this prediction. Mlc1p is also shown to interact with the class II conventional myosin (Myo1p). All three proteins form a complex, however, the interaction between Mlc1p and Iqg1p can be separated from the Mlc1p/Myo1p interaction. Mlc1p localisation and maintenance at the bud neck is independent of actin, Myo1p and Iqg1p. It is proposed that Mlc1p therefore functions to recruit Iqg1p and in turn actin to the actomyosin ring and that it is also required for Myo1p function during ring contraction.
Boyne
J R
JR
Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, PO Box 594, Western Bank, Sheffield S10 2TN, UK.
Yosuf
H M
HM
Bieganowski
P
P
Brenner
C
C
Price
C
C
D000483:Alleles; D002455:Cell Division; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D008938:Mitosis / Q000502:physiology; D016296:Mutagenesis; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D018994:Myosin Light Chains / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D020703:ras GTPase-Activating Proteins
D005656:Fungal Proteins; C101203:IQ motif containing GTPase activating protein 1; C113979:MLC1 protein, S cerevisiae; C112936:MYO1 protein, S cerevisiae; D008840:Microfilament Proteins; D018994:Myosin Light Chains; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D020703:ras GTPase-Activating Proteins; D018995:Myosin Heavy Chains