title: Molecular characterization of a Dictyostelium discoideum gene encoding a multifunctional enzyme of the pyrimidine pathway.
abstract: We have isolated and characterized a Dictyostelium discoideum gene (PYR1-3) encoding a multifunctional protein that carries the three first enzymatic activities of the de novo pyrimidine biosynthetic pathway. The PYR1-3 gene is adjacent to another gene of the pyrimidine biosynthetic pathway (PYR4); the two genes are separated by a 1.5-kb non-coding sequence and transcribed divergently. The PYR1-3 gene is transcribed to form a 7.5-kb polyadenylated mRNA. As with the other genes of the pyrimidine biosynthetic pathway, the PYR1-3 mRNA level is high during growth and decreases sharply during development. We have determined the nucleotide sequence of 63% of the coding region of the PYR1-3 gene. We have identified the activities of the protein encoded by the D. discoideum PYR1-3 gene by comparison of amino acid sequences with the products of genes of known function. The PYR1-3 gene contains four distinct regions that probably correspond to four domains in the protein. From the NH2 extremity to the COOH extremity, these domains are: glutamine amidotransferase, carbamoylphosphate synthetase, dihydroorotase and aspartate transcarbamylase. This organization is identical to the one found in the rudimentary gene of Drosophila. The evolutionary implications of this finding are discussed.
authors.affiliation: Laboratoires de Biologie Expérimentale, Université Paris-Sud.
authors.forename: M
authors.initials: M
authors.lastname: Faure
authors.forename: J H
authors.initials: JH
authors.lastname: Camonis
authors.forename: M
authors.initials: M
authors.lastname: Jacquet
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D005075:Biological Evolution; D003001:Cloning, Molecular; D015342:DNA Probes; D004023:Dictyostelium / Q000201:enzymology / Q000235:genetics*; D005796:Genes; D005815:Genetic Code; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009097:Multienzyme Complexes / Q000235:genetics*; D011743:Pyrimidines / Q000096:biosynthesis*; D014158:Transcription, Genetic
chemical_list: D015342:DNA Probes; D009097:Multienzyme Complexes; D011743:Pyrimidines