Evolutionary implications of the mosaic pyrimidine-biosynthetic pathway ineukaryotes

Citation
T. Nara et al., Evolutionary implications of the mosaic pyrimidine-biosynthetic pathway ineukaryotes, GENE, 257(2), 2000, pp. 209-222
Citations number
21
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Molecular Biology & Genetics
Journal title
GENE
ISSN journal
0378-1119 → ACNP
Volume
257
Issue
2
Year of publication
2000
Pages
209 - 222
Database
ISI
SICI code
0378-1119(20001031)257:2<209:EIOTMP>2.0.ZU;2-4
Abstract
The de-novo pyrimidine biosynthetic pathway involves six enzymes, in order from the first to the sixth step, carbamoylphosphate synthetase II (CPS II) comprising glutamine amidotransferase (GAT) and carbamoyl-phosphate synthe tase (CPS) domains or subunits, aspartate carbamoyltransferase (ACT), dihyd roorotase (DHO), dihydroorotate dehydrogenase (DHOD), orotate phosphoribosy ltransferase (OPRT), and orotidine-5'-monophosphate decarboxylase (OMPDC). In contrast with reports on molecular evolution of the individual enzymes, we attempted to draw an evolutionary picture of the whole pathway using the protein phylogeny. We demonstrate highly mosaic organizations of the pyrim idine biosynthetic pathway in eukaryotes. During evolution of the eukaryoti c pathway, plants and fungi (or their ancestors) in particular may have sec ondarily acquired the characteristic enzymes. This is consistent with the W et that the organization of plant enzymes is highly chimeric: (1) two subun its of CPS II, GAT and CPS, cluster with a clade including cyanobacteria an d red algal chloroplasts, (2) ACT not with a cyanobacterium, Synechocystis spp., irrespective of its putative signal sequence targeting into chloropla sts, and (3) DHO with a clade of proteobacteria. In fungi, DHO and OPRT dus ter respectively with the corresponding proteobacterial counterparts. The p hylogenetic analyses of DHOD and OMPDC also support the implications of the mosaic pyrimidine biosynthetic pathway in eukaryotes. The potential import ance of the horizontal gene transfer(s) and endosymbiosis in establishing t he mosaic pathway is discussed. (C) 2000 Elsevier Science B.V. All rights r eserved.