U. Reichard et al., Molecular characterization and influence on fungal development of ALP2, a novel serine proteinase from Aspergillus fumigatus, INT J MED M, 290(6), 2000, pp. 549-558
A novel subtilisin-related serine proteinase (ALP2) [EC 3.4.21.48] with a b
road range of activity between pH 4.5 and 11.0 was released from a cell wal
l fraction of Aspergillus fumigatus by an alkaline pH shift. The enzyme whi
ch was not detected in the culture supernatant was partially purified by ph
enylbutylamine agarose chromatography. The N-terminal sequence revealed tha
t ALP2 is the same protein identified as the major allergen of A. fumigatus
in patients suffering from extrinsic bronchial asthma (Shen et al. 1999, I
nt. Arch. Allergy Immunol. 119, 259-264). Based on this N-terminal sequence
and on a conserved region of fungal subtilisins, a specific PCR probe was
generated and the ALP2 genomic and cDNA were isolated from corresponding ph
age libraries. ALP2 shares a 49 % identity with the vacuolar proteinase B (
PrB) of Saccharomyces cerevisiae. In addition there is a 78 % identity with
PEPC, a serine proteinase which has been described in Aspergillus niger. T
argeted disruption of the ALP2-encoding gene resulted in a slightly decreas
ed speed of vegetative growth and in a more than 80% reduction of sporulati
on in the alp2-negative mutants, correlated with an approximately 50 % redu
ction of the median diameter of conidiophore vesicles. The requirement of A
LP2 for regular sporulation, in addition to its role in allergic asthma, ra
ises further interest in cellular proteinases in respect to morphogenesis a
nd pathogenesis in A. fumigatus.