Advances in Cytokinesis Research. Interactions of Cdc4p, a Myosin Light Chain, with IQ-domain Containing Proteins in Schizosaccharomyces pombe.

Abstract

ABSTRACT. The fission yeast

Cooperation Between the Septins and the Actomyosin Ring and Role of a Cell-Integrity Pathway During Cell Division in Fission Yeast

“…Cdc4 is thought to function as a light chain for both type II myosin heavy chains, Myo2 and Myp2 (Naqvi et al 1999;Motegi et al 2000;D'Souza et al 2001;Lord and Pollard 2004). Myo2 and Myp2 appear to be partially redundant for function in cytokinesis but are specialized such that myo2 is an essential gene whereas myp2 is essential only under particular growth conditions Motegi et al 2000).…”

“…Another hypothesis is that cdc4-s16 also compromises the function of some other Cdc4-binding partner that is part of a pathway that normally complements the pathway involving the septins. In this regard, it should be noted that there is good evidence that both S. pombe Cdc4 and its S. cerevisiae counterpart, Mlc1, interact with partners other than the type II myosin heavy chains and that these other partners are also important for cytokinesis (Stevens and Davis 1998;Boyne et al 2000;Shannon and Li 2000;Desautels et al 2001;D'Souza et al 2001;Motegi et al 2001;Win et al 2001;Lord and Pollard 2004;Luo et al 2004;Mulvihill et al 2006;Park et al 2009). The other partners include type V myosin heavy chains (S. pombe Myo51 and perhaps Myo52; S. cerevisiae Myo2), which are thought to be involved in the delivery of new plasma-membrane and cell-wall materials to the division site or (for Myo51) in some unknown function within the AMR; IQGAPs (S. pombe Rng2 and S. cerevisiae Iqg1), which may also be involved in plasma-membrane and cell-wall formation in addition to their roles in AMR function; and a phosphatidylinositol 4-kinase (S. pombe Pik1).…”

IQGAPs: Integrators of the cytoskeleton, cell adhesion machinery, and signaling networks

“…This protein, known as Rng2p, is localized to the cytokinetic ring in S. pombe [Eng et al, 1998], and like Iqg1p, binds a myosin light chain [D'Souza et al, 2001]. Finally, the slime mold, Dictyostelium discoideum, has been found to express a pair of IQGAPs that are involved in cytokinesis: GAPA [Adachi et al, 1997] and DGAP1 [Faix and Dittrich, 1996].…”

A calmodulin-related light chain from fission yeast that functions with myosin-I and PI 4-kinase

“…Class V myosins from budding yeast, fission yeast, Drosophila and chicken brains associate with the ELC (D'Souza et al, 2001;Espindola et al, 2000;Franke et al, 2006;Luo et al, 2004;Stevens and Davis, 1998) as do Drosophila myosin-VI and -VIIA associate with the ELC (Franke et al, 2006), whereas human myosin-X and Toxoplasma gondii myosin-XIV employ novel light chains (Herm-Gotz et al, 2002;Rogers and Strehler, 2001). …”

“…The ability of budding yeast myosin-V (Myo2p) to function in organelle and vesicle trafficking relies on its interaction with ELC Mlc1p (Altmann et al, 2008;Wagner et al, 2002). The essential role of the fission yeast ELC (Cdc4p) in contractile ring assembly and cytokinesis (Chang et al, 1996;McCollum et al, 1995) does not depend on myosin-II function because a myosin-II mutant lacking IQ motifs supports normal cytokinesis without suppressing the lethality of cdc4 mutants (D'Souza et al, 2001). Thus, cytokinesis defects associated with cdc4 alleles stem from a failure to function with other important ELC-binding partners.…”