The ASP1 gene of Saccharomyces cerevisiae, encoding the intracellular isozyme of L-asparaginase.
Saccharomyces cerevisiae produces two L-asparaginases (ASPs), intracellular ASP I and cell-wall ASP II. In this report, the ASP-I-encoding gene, ASP1, has been identified by homology cloning based on the structures of ASPs from other organisms. Its deduced protein product has a subunit M(r) of 41,414, and shows substantial sequence homology to the bacterial amidohydrolase family. The product of the S. cerevisiae ASP3 gene, a further member of this family, encoding the nitrogen catabolite-regulated cell-wall ASP II, has 46% overall sequence identity to ASP1. Duplication of ancestral asparaginase genes, resulting in separate intra- and extracellular isozymes, appears to have occurred independently in the prokaryotic and eukaryotic lineages. Exact physical mapping of the new cloned ASP1 gene locates it 73% of the distance from the left telomere of chromosome IV, at a position precisely matching the known genetic map location of ASP1. This, along with the structural features of the clone, confirms that ASP1 is the structural gene encoding cytoplasmic ASP I in S. cerevisiae. Sequence analysis of the ethylmethanesulfonate-induced asp1-12 allele of strain XE101-1A revealed a C-->T transition altering Ala176 to Val. This residue lies within a highly conserved region, and the results suggests a critical function for Ala176 in ASP function. Expression of ASP1 and other recombinant ASPs may allow access to improved products for use in the chemotherapy of leukaemia.
Human Genetics Unit, University of Edinburgh, Western General Hospital, UK.
K
K
Sinclair
J P
JP
Warner
D T
DT
Bonthron
D000595:Amino Acid Sequence; D001215:Asparaginase / Q000235:genetics*; D001483:Base Sequence; D005075:Biological Evolution; D002874:Chromosome Mapping; D015825:Chromosomes, Fungal; D003001:Cloning, Molecular; D004274:DNA, Recombinant; D007527:Isoenzymes / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D004274:DNA, Recombinant; D007527:Isoenzymes; D001215:Asparaginase