THE FILAMENTOUS FUNGUS ASPERGILLUS-NIGER CONTAINS 2 DIFFERENTIALLY REGULATED TREHALOSE-6-PHOSPHATE SYNTHASE-ENCODING GENES, TPSA AND TPSB

Two genes encoding trehalose-6-phosphate synthase were cloned from Asp ergillus niger. tpsA was cloned using the Saccharomyces cerevisiae GGS 1/TPS1 gene as a probe. It encodes a 517-amino acid polypeptide with 6 4-70% similarity to trehalose-6-phosphate synthase of S. cerevisiae, K luyveromyces lactis, and Schizosaccharomyces pombe. Its transcription occurs constitutively and is enhanced on carbon-derepressing carbon so urces, coinciding with the presence of a CreA-binding nucleotide motif in the 5'-noncoding region of tpsA. Disruption of tpsA only weakly re duces growth on glucose, and neither influences the glucose induction of a low affinity glucose permease nor interferes with the catabolite repression of a pectinase; it causes reduced the heat tolerance of con idia. tpsB was cloned by a polymerase chain reaction-based strategy. I ts 480 amino acid sequence showed 76.5% identity to tpsA. Its transcri ption was hardly detectable at ambient temperatures but was enhanced s trongly upon heat shock, which agrees with the presence of several cop ies of a C4T stress-responsive element in its 5'-upstream sequences. H ence the function of yeast GGS1/TPS1 has been split into two different ially regulated genes in A. niger, of which none appears to be involve d in glucose sensing.