title: Purine utilization proteins in the Eurotiales: cellular compartmentalization, phylogenetic conservation and divergence.
abstract: The purine utilization pathway has been thoroughly characterized in Aspergillus nidulans. We establish here the subcellular distribution of seven key intracellular enzymes, xanthine dehydrogenase (HxA), urate oxidase (UaZ), 5-hydroxy-isourate hydrolase (UaX), 2-oxo-4-hydroxy-4-carboxy ureido imidazoline decarboxylase (UaW), allantoinase (AlX), allantoicase (AaX), ureidoglycolate lyase (UglA), and the fungal-specific α-ketoglutarate Fe(II)-dependent dioxygenase (XanA). HxA, AlX, AaX, UaW and XanA are cytosolic, while UaZ, UaX and UglA are peroxisomal. Peroxisomal localization was confirmed by using appropriate pex mutants. The pathway is largely, but not completely conserved in the Eurotiomycetes, noticeably in some species AaX is substituted by an alternative enzyme of probable bacterial origin. UaZ and the urate-xanthine UapA and UapC transporters, are also localized in specific cells of the conidiophore. We show that metabolic accumulation of uric acid occurring in uaZ null mutations is associated with an increased frequency of appearance of morphologically distinct colony sectors, diminished conidiospore production, UV resistance and an altered response to oxidation stress, which may provide a rationale for the conidiophore-specific localization. The pathway-specific transcription factor UaY is localized in both the cytoplasm and nuclei under non-inducing conditions, but it rapidly accumulates exclusively to the nuclei upon induction by uric acid.
authors: Faculty of Biology, University of Athens, Panepistimioupolis, Athens 15784, Greece.
authors: Katerina
authors: K
authors: Galanopoulou
authors: Institut de Génétique et Microbiologie, Université Paris-Sud (XI), 91450 Orsay, France; Department of Microbiology, Imperial College London, South Kensington Campus, Flowers Building, Armstrong Road, London SW7 2AZ, UK.
authors: Claudio
authors: C
authors: Scazzocchio
authors: Faculty of Biology, University of Athens, Panepistimioupolis, Athens 15784, Greece.
authors: Maria Eleftheria
authors: ME
authors: Galinou
authors: Institut de Génétique et Microbiologie, Université Paris-Sud (XI), 91450 Orsay, France.
authors: Weiwei
authors: W
authors: Liu
authors: Faculty of Biology, University of Athens, Panepistimioupolis, Athens 15784, Greece.
authors: Fivos
authors: F
authors: Borbolis
authors: Faculty of Biology, University of Athens, Panepistimioupolis, Athens 15784, Greece.
authors: Mayia
authors: M
authors: Karachaliou
authors: Institut de Génétique et Microbiologie, Université Paris-Sud (XI), 91450 Orsay, France.
authors: Nathalie
authors: N
authors: Oestreicher
authors: Faculty of Biology, University of Athens, Panepistimioupolis, Athens 15784, Greece.
authors: Dimitris G
authors: DG
authors: Hatzinikolaou
authors: Faculty of Biology, University of Athens, Panepistimioupolis, Athens 15784, Greece.
authors: George
authors: G
authors: Diallinas
authors: Faculty of Biology, University of Athens, Panepistimioupolis, Athens 15784, Greece. Electronic address: samillis@biol.uoa.gr.
authors: Sotiris
authors: S
authors: Amillis
mesh_terms: D002467:Cell Nucleus; D003593:Cytoplasm / Q000737:chemistry; D032641:Eurotiales / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D005656:Fungal Proteins / Q000032:analysis* / Q000235:genetics*; D053858:Metabolic Networks and Pathways; D020675:Peroxisomes / Q000737:chemistry; D011687:Purines / Q000378:metabolism*; D013172:Spores, Fungal / Q000737:chemistry
chemical_list: D005656:Fungal Proteins; D011687:Purines
keywords: Aspergillus nidulans; Peroxisome; Transporter; Uric acid