Growth, Differentiation and Sexuality

108 J. Wendland and A. Walther
Table. 6.1. (continued)
A. gossypii N. crassa S. cerevisiae
Mitotic exit
AFR035W (0.0) NCU03242.1 (e-053),
NCU07296.1 (e-146)
YNL161W CBK1
ACL006W (0.0) NCU09258.1 (e-063) YMR001C CDC5
ADR033W (0.0) NCU09071.1 (e-135) YGR092W, YPR111W DBF2, DBF20
ADL149W (e-170) NCU00622.1 (e-056) YHR158C, YGR238C KEL1, KEL2
ACR292W (0.0) NCU03379.1 (e-041) YAL024C LTE1
ADR317C (e-175) NCU00978.1 (e-072) YDL028C MPS1
AER425W (e-007),
syntenic homolog
None YNL078W NIS1
Actin ring formation and cytokinesis
AFR669W (0.0) NCU01431.1 (e-085) YNL271C BNI1
ABL200W (e-062) NCU00064.1 (e-014) YNL233W BNI4
AFR027C (e-031) None YNL166C BNI5
AFR301C (e-118) None YIL159W BNR1
ABL153W (0.0) NCU04251.1 (0.0) YNL192W CHS1
AEL190W (0.0) NCU05239.1 (0.0) YBR038W CHS2
AEL189W (0.0) NCU09324.1 (0.0),
YBR023C CHS3
NCU04350.1 (e-122)
ACR227W (e-156) NCU02351.1 (e-032),
NCU02592.1 (e-042),
NCU09322.1 (e-076)
YBL061C SKT5/CHS4
ADL288C (0.0) NCU04095.1 (e-045) YDL117W CYK3
ABR082W (e-080) NCU04763.1 (e-017) YMR032W HOF1/CYK2
AFL150C (0.0) NCU03116.1 (e-048) YPL242C IQG1/CYK1
AFL030C (e-051) NCU06617.1 (e-024) YGL106W MLC1
AEL280W (e-022) None YPR188C MLC2
ACR068W (0.0) NCU00551.1 (0.0) YHR023W MYO1
a Ashbya gossypii sequences correspond to the systematic nomenclature (http://agd.unibas.ch/); Neurospora crassa sequences
correspond to the genome annotation available at http://www.broad.mit.edu/annotation/fungi/neurospora_crassa
_7/index.html. Values in brackets indicate the e-values generated by using BLAST-P of the fungal sequences against the S.
cerevisiae protein. An e-value of 0.0 indicates very high sequence identity. Syntenic homology (conserved chromosomal
gene order of homologs) between Ashbya and S. cerevisiae genes was used to indicate homology, despite low e-value blast
scores. E-values from Ashbya to S. cerevisiae comparisons were found to be higher than those of N. crassa to S. cerevisiae
comparisons, reflecting the closer relationship of the former species pair
Bud8p and Bud5p (Roemer et al. 1996; Kang et al.
2001, 2004a).
B. Placement of the Site of Cell Division
in Schizosaccharomyces pombe
Thecleavageplane,andthustheseptumposition
in S. pombe is selected in a manner similar to that
of animal cells, which has made S. pombe amodel
organism to study cell division. However, in animal
cells, selection of the cleavage plane is dependent on
spindle microtubules forming a structure termed
‘midbody’, whereas in S. pombe the mitotic spindle
can be disrupted without interfering with the
selection of the septal site (Chang et al. 1996). This
may reflect a difference in nuclear division, which
occurs as a closed mitosis in S. pombe, in which the
nuclear envelope is not broken down (Chang 2001).
In S. pombe, positioning of the nucleus is important
for the placement of the division site, since
mispositioning of the nucleus is followed by an
aberrant localization of the division plane (Chang
and Nurse 1996; Chang et al. 1996; Tran et al. 2001).
TheMid1/Dmf1proteinwasshowntoplayanessential
role in the positioning of the cleavage plane,
and may encode a landmark protein defining the
septal site (Sohrmann et al. 1998). Mutants of mid1
are still able to form actin rings, but the positioning
of the ring is randomized at different angles. Mid1p
is localized in the nucleus in interphase cells but exits
the nucleus upon phosphorylation during mitosis,
regulated via the polo-like kinase Plo1 (Ohkura
et al. 1995; Bähler et al. 1998; Fig. 6.1B). Mid1p
then forms a band on the cell cortex in the vicinity
of the nucleus, and this localization is dependent
on the position of the nucleus, since nuclear po-