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Type: Journal article
Title: A eukaryotic nicotinate-inducible gene cluster: convergent evolution in fungi and bacteria
Author: Ámon, J.
Fernández-Martín, R.
Bokor, E.
Cultrone, A.
Kelly, J.
Flipphi, M.
Scazzocchio, C.
Hamari, Z.
Citation: Open Biology, 2017; 7(12):170199-1-170199-17
Publisher: Royal Society
Issue Date: 2017
ISSN: 2046-2441
Statement of
Judit Ámon, Rafael Fernández-Martín, Eszter Bokor, Antonietta Cultrone, Joan M. Kelly, Michel Flipphi, Claudio Scazzocchio and Zsuzsanna Hamari
Abstract: Nicotinate degradation has hitherto been elucidated only in bacteria. In the ascomycete Aspergillus nidulans, six loci, hxnS/AN9178 encoding the molybdenum cofactor-containing nicotinate hydroxylase, AN11197 encoding a Cys2/His2 zinc finger regulator HxnR, together with AN11196/hxnZ, AN11188/hxnY, AN11189/hxnP and AN9177/hxnT, are clustered and stringently co-induced by a nicotinate derivative and subject to nitrogen metabolite repression mediated by the GATA factor AreA. These genes are strictly co-regulated by HxnR. Within the hxnR gene, constitutive mutations map in two discrete regions. Aspergillus nidulans is capable of using nicotinate and its oxidation products 6-hydroxynicotinic acid and 2,5-dihydroxypyridine as sole nitrogen sources in an HxnR-dependent way. HxnS is highly similar to HxA, the canonical xanthine dehydrogenase (XDH), and has originated by gene duplication, preceding the origin of the Pezizomycotina. This cluster is conserved with some variations throughout the Aspergillaceae. Our results imply that a fungal pathway has arisen independently from bacterial ones. Significantly, the neo-functionalization of XDH into nicotinate hydroxylase has occurred independently from analogous events in bacteria. This work describes for the first time a gene cluster involved in nicotinate catabolism in a eukaryote and has relevance for the formation and evolution of co-regulated primary metabolic gene clusters and the microbial degradation of N-heterocyclic compounds.
Keywords: Nicotinate catabolic gene cluster; convergent evolution; nicotinate hydroxylase; xanthine dehydrogenase; Cys2His2 transcription factor
Rights: © 2017 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License, which permits unrestricted use, provided the original author and source are credited.
RMID: 0030080902
DOI: 10.1098/rsob.170199
Appears in Collections:Environment Institute publications

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