The sequence of palF, an environmental pH response gene in Aspergillus nidulans

To molecularly characterize the influence of external pH in the secretion of enzymes by filamentous fungi, we have cloned and sequenced the palF gene of Aspergillus nidulans (An). An An wild-type (wt) chromosome VII-specific cosmid library was used to transform a palF15 mutant strain. Selection for complementation was done on medium containing beta-glycerolphosphate as the sole Pi source. Two cosmids were identified (W2G08 and W4G12) and further subcloning of one cosmid (W2G08) defined a 5-kb PstI genomic fragment, which fully complements the palF15 mutation. An internal fragment from the genomic clone recognized a single message of approx. 3.5 kb on Northern blot. cDNA clones were obtained from a lambda gt10 cDNA library and sequenced, showing a nucleotide (nt) sequence of 3311 base pairs (bp), with a 828 bp long 5'-untranslated region (UTR). The major open reading frame (ORF) identified in the sequence codes for a putative 775 amino acid (aa) protein, which shares some similarity with two putative ORF products of Saccharomyces cerevisiae (Sc).