Occurrence of multiple, independent gene fusion events for the fifth and sixth enzymes of pyrimidine biosynthesis in different eukaryotic groups.
The genes encoding orotate phosphoribosyltransferase (OPRT) and orotidine-5'-monophosphate decarboxylase (OMPDC), the fifth and sixth enzymes in the de novo pyrimidine biosynthetic pathway, are fused as OPRT-OMPDC in most eukaryotic groups. On the other hand, the inversely linked OMPDC-OPRT fusion is present in trypanosomatids, belonging to kinetoplastids together with bodonids in a supergroup, Euglenozoa. Here, we show the presence of OMPDC-OPRT in the bodonid, Bodo caudatus, while OPRT-OMPDC in Euglena gracilis, another euglenozoan species belonging to euglenoids. These results suggest that the OMPDC-OPRT fusion event occurred in a common ancestor of kinetoplastids. Genome sequence database searches further revealed the presence of OMPDC-OPRT in stramenopiles and cyanobacteria. Phylogenetic reconstruction of OPRT and OMPDC rejected statistically the monophyly of the OPRT domains of stramenopile and kinetoplastid OMPDC-OPRT, demonstrating that these gene fusions do not share a common evolutionary origin, despite the identical gene order. Thus, the OMPDC-OPRT fusion is likely to have emerged independently in these eukaryotic groups. Phylogenetic analyses also suggested that cyanobacterial OMPDC-OPRT arose via lateral transfer. We conclude that gene fusion events occur more frequently than previously thought and that lateral gene transfer has made a marked contribution to establishment of the rearranged structure of OPRT and OMPDC genes in eukaryotes.
Makiuchi
Takashi
T
Department of Molecular and Cellular Parasitology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan.
Nara
Takeshi
T
Annoura
Takeshi
T
Hashimoto
Tetsuo
T
Aoki
Takashi
T
D000818:Animals; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000235:genetics / Q000378:metabolism; D048028:DNA, Algal / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics; D005056:Euglena gracilis / Q000235:genetics* / Q000378:metabolism*; D019143:Evolution, Molecular; D050939:Gene Fusion; D022761:Gene Transfer, Horizontal; D017125:Genes, Protozoan; D016830:Kinetoplastida / Q000235:genetics* / Q000378:metabolism*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D011743:Pyrimidines / Q000096:biosynthesis*; D013045:Species Specificity
D048028:DNA, Algal; D018076:DNA, Complementary; D016054:DNA, Protozoan; D011743:Pyrimidines