Growth, Differentiation and Sexuality

Fig. 15.6. Amino-acid alignment of the HPG domain
of deduced MAT1-1-2 proteins of Sordariomycetes.
N. crassa (AAC37477), S. macrospora (CAA71626), P.
anserina (S39889), C. globosum MAT1-1 and MAT1-2
(Broad Institute), G. moniliformis/fujikuroi (AAC71054),
teins (PSORT II, Nakai and Horton 1999) does not
detect any nuclear localization signal and predicts
a cytoplasmic localization. PSORT II analyses of all
MAT1-1-2 proteins listed in Fig. 15.6 predict that
they should have a cytoplasmic localization, except
MAT1-1-2 of M. grisea. The latter protein was
predicted to be nucleus localized, but no nuclear
localization signal was detected. Taken together,
these data suggest that Podospora SMR1 has a cytoplasmic
localization, but its molecular function
remains unknown.
3. MAT1-1-3 and MAT1-2-1
The high-mobility-group (HMG) domain is a DNAbinding
sequence found in non-histone chromosomal
proteins and transcription factors. Fungal
mating-type transcription factors, like MAT1-1-3
Fig. 15.7. Amino-acid alignment of the HMG domain of
deduced MAT1-1-3 proteins of Euascomycetes. G. moniliformis
(AAC71053), F. oxysporum (Yun et al. 2000), G.
zeae (AAG42812), C. parasitica (AAK83344), P. anserina
(CAA52051), C. globosum (Broad Institute), P. brassicae
Mating Types in Euascomycetes 309
F. oxysporum (Yun et al. 2000), G. zeae (AAG42811), P.
tenuipes (BAC67540), C. parasitica (AAK83345), M. grisea
(BAC65088). Fraction of sequences that must agree for
shading:0.8
and MAT1-2-1, belong to the MATA_HMG box family,
while other transcription factors, notably HMG
transcription factors from animals, are classified
in the SOX-TCF_HMG box family. MAT1-2-1 and
MAT1-1-3 genes are characterized by a conserved
intron inside the HMG encoding sequence. This
intron is localized after the first nucleotide of the
triplet encoding the invariant residue serine in the
lS and neiS residues in MAT1-1-3 and MAT1-2-1,
respectively (Figs. 15.7 and 15.8). Genes encoding
proteins from the SOX-TCF_HMG box family do
not contain an intron at this position. Although
structural gene features seem in agreement with
the current classification of HMG transcription factors,
it may be that this classification does not correspond
to their DNA-binding properties. Philley and
Staben have established that the MAT a-1 HMG domain
from N. crassa binds specific DNA sequences
(CAA06846), R. secalis (CAD71142), M. grisea, partial sequence
(Kanamori and Arie, personal communication), N.
crassa (AAC37476), C. albicans (Butler et al. 2004), Y. lipolytica
(CAA07613). Fraction of sequences that must agree for
shading:0.7