Cortical Num1p Interacts with the Dynein Intermediate Chain Pac11p and Cytoplasmic Microtubules in Budding Yeast

Abstract

Num1p, a cortical 313-kD protein, controls cytoplasmic microtubule (cMT) functions and nuclear migration through the bud neck in anaphase cells. A green fluorescent protein (GFP)-Num1p fusion protein localizes at the bud tip and the distal mother pole of living cells, apparently forming cMT capture sites at late anaphase. In addition, galactose-induced GFP-Num1p is seen at the bud neck and in lateral regions of the mother cortex. The bud tip location of Num1p depends on Bni1p but does not require Kar9p, Dyn1p, or cMTs, whereas cMT contacts with polar Num1p dots are reduced in cells lacking Dyn1p. Num1p associates with the dynein intermediate chain Pac11p in the presence of Dyn1p, and with the α-tubulin Tub3p, as shown by coimmune precipitation of tagged proteins. Num1p also forms a complex with Bni1p and Kar9p, although Num1p is not required for Bni1p- and Kar9p-dependent nuclear migration to the bud neck in preanaphase cells.Our data suggest that Num1p controls nuclear migration during late anaphase by forming dynein-interacting cortical cMT capture sites at both cellular poles. In addition, Num1p may transiently cooperate with an associated Bni1p–Kar9p complex at the bud tip of early anaphase cells.

Microtubule capture by the cleavage apparatus is required for proper spindle positioning in yeast

“…At the same temperature cdc12-1 dhc1, cdc12-1 num1, and cdc12-1 bik1 cells were unable to do more than a few divisions (Fig. 6A, Num1 and Bik1 act in the dynein pathway; Pellman et al 1995;Farkasovsky and Kuntzel 2001). Analysis of the cdc12-1 dhc1 cells showed that the mother cells rapidly became multinucleated (data not shown).…”

A nuclear contortionist: the mitotic migration ofMagnaporthe oryzaenuclei during plant infection

“…For example, in S. cerevisiae , astral microtubules are nucleated at the spindle pole body and rely on dynamic instability to search the cell cortex of the bud to locate Num1, a cortical dynein-interacting protein (Carminati and Stearns 1997; Heil-Chapdelaine et al 2000; Farkasovsky and Küntzel 2001). Once the plus-ends of astral microtubules bind to Num1, they slide against the cell cortex in a dynein-mediated manner which moves the spindle and eventually the daughter nucleus into the newly formed bud (Heil-Chapdelaine et al 2000).…”

Genetic evidence for a microtubule-capture mechanism during polar growth of Aspergillus nidulans

“…3D, supplementary material Fig. S3B) (Fischer and Timberlake, 1995) in the same fashion that S. cerevisiae Kar9 interacts with Num1 (Farkasovsky and Kuntzel, 2001), bimolecular fluorescence complementation (BiFC) and yeast two-hybrid analyses were performed. BiFC analysis showed an interaction of the two proteins at the plasma membrane throughout the fungal hyphae and also occasionally at septa (Fig.…”