The aspartate transcarbamoylase-dihydroorotase complex in Deinococcus radiophilus has an active dihydroorotase.
Aspartate transcarbamoylase (ATCase) and dihydroorotase (DHOase) catalyse the first two steps unique to pyrimidine synthesis. In many bacteria they form non-covalently bonded complexes. There are two types of DHOase, type I and type II which share a common ancestry. Type I is the more ancient form and is present in the complexes. In recently evolved bacteria the DHOase is defective and its function has been replaced by a type II DHOase which is separate from the complex. Deinococcus radiophilus diverges early on the phylogenetic tree and so might be expected to have an active type I DHOase. Purification of the 500 kDa ATCase-DHOase complex, by conventional techniques, showed it to possess an active DHOase.
McPhail
Donald
D
Faculty of Applied Sciences, University of the West of England, Coldharbour Lane, BS16 1QY, Bristol, UK.
Shepherdson
Margaret
M
D001221:Aspartate Carbamoyltransferase / Q000737:chemistry / Q000378:metabolism*; D002845:Chromatography / Q000379:methods; D034301:Deinococcus / Q000201:enzymology*; D004080:Dihydroorotase / Q000737:chemistry / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism*; D011743:Pyrimidines / Q000096:biosynthesis; D012988:Soil Microbiology
D009097:Multienzyme Complexes; D011743:Pyrimidines; D001221:Aspartate Carbamoyltransferase; D004080:Dihydroorotase; C030986:pyrimidine