The Fungus Tremella mesenterica Encodes the Longest Metallothionein Currently Known : Gene, Protein and Metal Binding Characterization
Iturbe-Espinoza, Paul (Universitat de Barcelona. Departament de Genètica, Microbiologia i Estadística)
Gil-Moreno, Selene (Universitat Autònoma de Barcelona. Departament de Química)
Lin, Weiyu (Universitat de Barcelona. Departament de Genètica, Microbiologia i Estadística)
Calatayud, Sara (Universitat de Barcelona. Departament de Genètica, Microbiologia i Estadística)
Palacios Bonilla, Òscar (Universitat Autònoma de Barcelona. Departament de Química)
Capdevila Vidal, Mercè (Universitat Autònoma de Barcelona. Departament de Química)
Atrian i Ventura, Sílvia (Universitat de Barcelona. Departament de Genètica, Microbiologia i Estadística)

Data:	2016
Resum:	Fungal Cu-thioneins, and among them, the paradigmatic Neurospora crassa metallothionein (MT) (26 residues), were once considered as the shortest MTs -the ubiquitous, versatile metal-binding proteins- among all organisms, and thus representatives of their primeval forms. Nowadays, fungal MTs of diverse lengths and sequence features are known, following the huge heterogeneity of the Kingdom of Fungi. At the opposite end of N. crassa MT, the recently reported Cryptococcus neoformans CnMT1 and CnMT2 (122 and 186 aa) constitute the longest reported fungal MTs, having been identified as virulence factors of this pathogen. CnMTs are high-capacity Cu-thioneins that appear to be built by tandem amplification of a basic unit, a 7-Cys segment homologous to N. crassa MT. Here, we report the in silico, in vivo and in vitro study of a still longer fungal MT, belonging to Tremella mesenterica (TmMT), a saprophytic ascomycete. The TmMT gene has 10 exons, and it yields a 779-bp mature transcript that encodes a 257 residue-long protein. This MT is also built by repeated fragments, but of variable number of Cys: six units of the 7-Cys building blocks-CXCXCSCPPGXCXCAXCP-, two fragments of six Cys, plus three Cys at the N-terminus. TmMT metal binding abilities have been analyzed through the spectrophotometric and spectrometric characterization of its recombinant Zn-, Cd- and Cu-complexes. Results allow it to be unambiguous classified as a Cu-thionein, also of extraordinary coordinating capacity. According to this feature, when the TmMT cDNA is expressed in MT-devoid yeast cells, it is capable of restoring a high Cu tolerance level. Since it is not obvious that T. mesenterica shares the same physiological needs for a high capacity Cu-binding protein with C. neoformans, the existence of this peculiar MT might be better explained on the basis of a possible role in Cu-handling for the Cu-enzymes responsible in lignin degradation pathways.
Ajuts:	Ministerio de Economía y Competitividad BIO2012-39682-C02-01 Agència de Gestió d'Ajuts Universitaris i de Recerca 2014/SGR-423
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Publicat a:	PloS one, Vol. 11, Issue 2 (February 2016) , art. e0148651, ISSN 1932-6203

DOI: 10.1371/journal.pone.0148651
PMID: 26882011

22 p, 6.1 MB

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