An anillin homologue, Mid2p, acts during fission yeast cytokinesis to organize the septin ring and promote cell separation.

Tasto JJ, Morrell JL, Gould KL
J Cell Biol. 2003 160 (7): 1093-103

PMID: 12668659 · PMCID: PMC2172762 · DOI:10.1083/jcb.200211126

Anillin is a conserved protein required for cell division (Field, C.M., and B.M. Alberts. 1995. J. Cell Biol. 131:165-178; Oegema, K., M.S. Savoian, T.J. Mitchison, and C.M. Field. 2000. J. Cell Biol. 150:539-552). One fission yeast homologue of anillin, Mid1p, is necessary for the proper placement of the division site within the cell (Chang, F., A. Woollard, and P. Nurse. 1996. J. Cell Sci. 109(Pt 1):131-142; Sohrmann, M., C. Fankhauser, C. Brodbeck, and V. Simanis. 1996. Genes Dev. 10:2707-2719). Here, we identify and characterize a second fission yeast anillin homologue, Mid2p, which is not orthologous with Mid1p. Mid2p localizes as a single ring in the middle of the cell after anaphase in a septin- and actin-dependent manner and splits into two rings during septation. Mid2p colocalizes with septins, and mid2 Delta cells display disorganized, diffuse septin rings and a cell separation defect similar to septin deletion strains. mid2 gene expression and protein levels fluctuate during the cell cycle in a sep1- and Skp1/Cdc53/F-box (SCF)-dependent manner, respectively, implying that Mid2p activity must be carefully regulated. Overproduction of Mid2p depolarizes cell growth and affects the organization of both the septin and actin cytoskeletons. In the presence of a nondegradable Mid2p fragment, the septin ring is stabilized and cell cycle progression is delayed. These results suggest that Mid2p influences septin ring organization at the site of cell division and its turnover might normally be required to permit septin ring disassembly.

MeSH Terms (24)

Actins Amino Acid Sequence Calcium-Binding Proteins Cell Division Contractile Proteins Cyclin-Dependent Kinases DNA-Binding Proteins Fungal Proteins Gene Deletion Gene Expression Regulation, Fungal Genes, Fungal Green Fluorescent Proteins Humans Intracellular Signaling Peptides and Proteins Luminescent Proteins Membrane Glycoproteins Membrane Proteins Molecular Sequence Data Mutation Protein Structure, Tertiary Recombinant Fusion Proteins Saccharomyces cerevisiae Proteins Schizosaccharomyces Sequence Homology, Amino Acid

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