Affiliation:
1. Department of Microbiology, Molecular Biology and Biochemistry, Center for Reproductive Biology, University of Idaho, Moscow, Idaho
Abstract
ABSTRACT
The lack of an experimentally amenable sexual genetic system in
Aspergillus fumigatus
is a major limitation in the study of the organism's pathogenesis. A recent comparative genome analysis revealed evidence for potential sexuality in
A. fumigatus
. Homologs of mating type genes as well as other genes of the “sexual machinery” have been identified in anamorphic
A. fumigatus
. The
mat1
-
2
gene encodes a homolog of MatA, an HMG box mating transcriptional factor (Mat
HMG
) that regulates sexual development in fertile
Aspergillus nidulans
. In this study, the functionalities of
A. fumigatus mat1
-
2
and the Mat1-2 protein were determined by interspecies gene exchange between sterile
A. fumigatus
and fertile
A. nidulans
. Ectopically integrated
A. fumigatus mat1
-
2
(driven by its own promoter) was not functional in a sterile
A. nidulans
Δ
matA
strain, and no sexual development was observed. In contrast, the
A. fumigatus mat1
-
2
open reading frame driven by the
A. nidulans matA
promoter and integrated by homologous gene replacement at the
matA
locus was functional and conferred full fertility. This is the first report showing that cross species mating type gene exchange between closely related
Ascomycetes
did not function in sexual development. This is also the first report demonstrating that a Mat
HMG
protein from an asexual species is fully functional, with viable ascospore differentiation, in a fertile homothallic species. The expression of
mat1
-
2
was assessed in
A. fumigatus
and
A. nidulans
. Our data suggest that
mat1
-
2
may not be properly regulated to allow sexuality in
A. fumigatus
. This study provides new insights about
A. fumigatus
asexuality and also suggests the possibility for the development of an experimentally amenable sexual cycle.
Publisher
American Society for Microbiology
Subject
Molecular Biology,General Medicine,Microbiology