Dictyostelium Aurora kinase has properties of both Aurora A and Aurora B kinases.
ABSTRACT Aurora kinases are highly conserved proteins with important roles in mitosis. Metazoans contain two kinases, Aurora A and B, which contribute distinct functions at the spindle poles and the equatorial region respectively. It is not currently known whether the specialized functions of the two kinases arose after their duplication in animal cells or were already present in their ancestral kinase. We show that Dictyostelium discoideum contains a single Aurora kinase, DdAurora, that displays characteristics of both Aurora A and B. Like Aurora A, DdAurora has an extended N-terminal domain with an A-box sequence and localizes at the spindle poles during early mitosis. Like Aurora B, DdAurora binds to its partner DdINCENP and localizes on centromeres at metaphase, the central spindle during anaphase, and the cleavage furrow at the end of cytokinesis. DdAurora also has several unusual properties. DdAurora remains associated with centromeres in anaphase, and this association does not require an interaction with DdINCENP. DdAurora then localizes at the cleavage furrow, but only at the end of cytokinesis. This localization is dependent on DdINCENP and the motor proteins Kif12 and myosin II. Thus, DdAurora may represent the ancestral kinase that gave rise to the different Aurora kinases in animals and also those in other organisms.
Article: A mitotic kinesin-like protein required for normal karyokinesis, myosin localization to the furrow, and cytokinesis in Dictyostelium.[show abstract] [hide abstract]
ABSTRACT: Dictyostelium mitotic kinesin Kif12 is required for cytokinesis. Myosin II localization to the cleavage furrow is severely depressed in Kif12-null (Deltakif12) cells, which accounts in part for the cytokinesis failure. Myosin II-null cells, however, undergo mitosis-coupled cytokinesis when adhering to a surface, whereas the Deltakif12 cells cannot. During mitosis, the rate of change of internuclear separation in Deltakif12 cells is reduced compared with wild-type cells, indicating multiple roles of this molecular motor during mitosis and cytokinesis. GFP-Kif12, which rescues wild-type behavior when expressed in the Deltakif12 strain, is concentrated in the nucleus in interphase cells, translocates to the cytoplasm at the onset of mitosis, appears in the centrosomes and spindle, and later is concentrated in the spindle midbody. Given these results, we hypothesize a mechanism for myosin II translocation to the furrow to set up the contractile ring.Proceedings of the National Academy of Sciences 12/2004; 101(47):16519-24. · 9.68 Impact Factor
Article: The CaMV 35S enhancer contains at least two domains which can confer different developmental and tissue-specific expression patterns.[show abstract] [hide abstract]
ABSTRACT: We have analyzed expression conferred by two domains from the cauliflower mosaic virus (CaMV) 35S promoter and found different patterns in seeds, seedlings and seven week old plants. Expression from domain A (-90 to +8) is strongest in the radicle of the embryo, the radicle pole of the endosperm and in root tissue of seedlings and mature plants. Expression from domain B (-343 to -90) is strongest in the cells adjacent the cotyledon of the endosperm, in the cotyledons of the embryo and seedings and in the leaves and stem of mature plants. When both domain A and domain B are present expression is detectable in most tissues at all stages of development. Thus analysis of a constitutive promoter in transgenic plants can be used to identify cis elements that confer tissue specific and developmentally regulated expression.The EMBO Journal 09/1989; 8(8):2195-202. · 9.20 Impact Factor