Figure 1. C-terminal mutation of sid4 suppresses the cut12.1 SPB activation defect. (A) Representative images of immunofluorescence to reveal tubulin, the spindle pole marker Sad1, and chromatin 3 h after the temperature of an early log-phase culture was shifted from 25°C to 36°C in EMM2. n = 5. Arrows indicate the two SPBs. BF, brightfield. (B) A cartoon summarizing the SPB molecules upon which this study focuses. The representation is highly stylized because the mode of anchoring to the SPB core remains unclear for Ppc89 and Cut12, however. Cut12 is known to promote mitotic commitment (red arrows), whereas the anchorage of Sid4 to the SPB by Ppc89 enables Sid4 to anchor Cdc11 to the SPB. As Cdc11 recruits the SIN to the new SPB in anaphase, the recruitment of Cdc11 to Sid4 supports the events of mitotic exit such as septation and the formation of the equatorial microtubule-organizing center (Heitz et al., 2001; Simanis, 2015). (C and D) Representative graphs indicating the frequency of spindle monopolarity in samples of the indicated strains 3 h after early log phase cultures were shifted from 25°C to 36°C. For each strain, 100 cells with spindle staining were scored as being either bipolar or monopolar. n = 3. Note that the SPB activation delay of cut12.1 means that monopolarity gives an underestimate of the incidence of SPB activation defects (Tallada et al., 2009). See also Fig. S1 A. (E) A schematic of the characterized associations of the indicated SPB components. The core SPB and SIN are indicated in gray. It is not clear whether only one or both of the components of the Sid4 dimer binds to Cdc11 or Ppc89. The coiled-coil regions in Ppc89 have prompted us to show Ppc89 as a dimer; however, we note that homodimerization or higher levels of oligomerization are yet to be demonstrated. (F) The position of key mutations within an alignment of the sequences of the C termini of Sid4 from Schizosaccharomyces species and Pneumocystis murina.
Figure 1.

C-terminal mutation of sid4 suppresses the cut12.1 SPB activation defect. (A) Representative images of immunofluorescence to reveal tubulin, the spindle pole marker Sad1, and chromatin 3 h after the temperature of an early log-phase culture was shifted from 25°C to 36°C in EMM2. n = 5. Arrows indicate the two SPBs. BF, brightfield. (B) A cartoon summarizing the SPB molecules upon which this study focuses. The representation is highly stylized because the mode of anchoring to the SPB core remains unclear for Ppc89 and Cut12, however. Cut12 is known to promote mitotic commitment (red arrows), whereas the anchorage of Sid4 to the SPB by Ppc89 enables Sid4 to anchor Cdc11 to the SPB. As Cdc11 recruits the SIN to the new SPB in anaphase, the recruitment of Cdc11 to Sid4 supports the events of mitotic exit such as septation and the formation of the equatorial microtubule-organizing center (Heitz et al., 2001; Simanis, 2015). (C and D) Representative graphs indicating the frequency of spindle monopolarity in samples of the indicated strains 3 h after early log phase cultures were shifted from 25°C to 36°C. For each strain, 100 cells with spindle staining were scored as being either bipolar or monopolar. n = 3. Note that the SPB activation delay of cut12.1 means that monopolarity gives an underestimate of the incidence of SPB activation defects (Tallada et al., 2009). See also Fig. S1 A. (E) A schematic of the characterized associations of the indicated SPB components. The core SPB and SIN are indicated in gray. It is not clear whether only one or both of the components of the Sid4 dimer binds to Cdc11 or Ppc89. The coiled-coil regions in Ppc89 have prompted us to show Ppc89 as a dimer; however, we note that homodimerization or higher levels of oligomerization are yet to be demonstrated. (F) The position of key mutations within an alignment of the sequences of the C termini of Sid4 from Schizosaccharomyces species and Pneumocystis murina.

This Feature Is Available To Subscribers Only

or Create an Account

Close Modal
Close Modal