L-asparaginase is an amidohydrolase that catalyzes the hydrolysis of asparagine to aspartic acid and ammonia. Asparaginases are classified into two categories, type I and type II, the latter being regulated. Aspergillus nidulans has two asparaginase genes, apnA (on chromosome II) and ahrA (on chromosome VIII). The enzyme expressed by the ahrA gene is categorized as a type II asparaginase [Shaffer et al. (1988) Mol. Gen. Genet. 212, 337-341]. With the help of Cereon Genomics, LLC (subsidiary of Monsanto) and Whitehead Institute (WI) databases we obtained the sequences of both asparaginase genes. From these sequences we prepared PCR primers and used them with genomic DNA [wild type A4(Glasgow)] to produce nucleotide sequences (1214 nucleotides containing the ahrA gene and 706 nucleotides containing the apnA gene), as well as for a mutant of each. Next we prepared labeled sequences for each gene and probed a UniZap cDNA library. We have the cDNA for the ahrA gene and are in the process of obtaining the cDNA for the apnA gene. The expression of each of these genes is in the planning stages. Since type II asparaginases are used as a cure for childhood acute lymphoblastic leukemia (ALL), this research may have some pharmaceutical significance. We are grateful to Graduate Women in Science for funding and Mark Caddick scientific input.
Full conference title:
23rd Fungal Genetics Conference
- Fungal Genetics Conference 23rd (2002)