Regulation of Rho-GEF Rgf3 by the arrestin Art1 in fission yeast cytokinesis.
Bottom Line: Rgf3 is an essential GEF for Rho1 GTPase in fission yeast.Biochemical experiments reveal that the Rgf3 C-terminus binds to Art1.Using an Rgf3 conditional mutant and mislocalization experiments, we found that Art1 and Rgf3 are interdependent for localization to the division site.
Affiliation: Graduate Program of Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, OH 43210 Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210.Show MeSH
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Mentions: To further understand Art1 function during later stages of cytokinesis, we examined its localization using a monomeric enhanced Citrine (mECitrine; yellow fluorescent protein [YFP] variant)-tagged strain. Art1 concentrated to the contractile ring during cytokinesis (Figure 2, A–C, arrowheads). After ring constriction, the Art1 signal spread unevenly onto the septal disk (Figure 2, A–C, arrows). In addition, Art1 also diffused in the cytoplasm at all stages of the cell cycle. A compact contractile ring forms from cytokinetic nodes at the end of anaphase A in wt cells, when the spindle is ∼2.5 μm long (Wu et al., 2003; Lee et al., 2012). Using time-lapse microscopy, we found that Art1 appeared directly in the contractile ring (not in the precursor nodes), increased in fluorescence intensity, constricted, and then spread to the septum (Figure 2D). Art1 appeared in the contractile ring when spindle pole bodies (SPBs) were ∼3 μm apart (Figure 2, E and F), corresponding to the maturing contractile ring in wt cells at early anaphase B (Nabeshima et al., 1998; Mallavarapu et al., 1999; Wu et al., 2003). It remained at the division site until cell separation. Thus the pattern of Art1 localization is consistent with its role in contractile-ring maturation, ring constriction, and septal integrity.
Affiliation: Graduate Program of Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, OH 43210 Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210.