The Saccharomyces cerevisiae Crs5 Metallothionein metal-binding abilities and its role in the response to zinc overload.
Crs5 is a Saccharomyces cerevisiae Metallothionein (MT), non-homologous to the paradigmatic Cu-thionein Cup1. Although considered a secondary copper-resistance agent, we show here that it determines survival under zinc overload in a CUP1-null background. Its overexpression prevents the deleterious effects exhibited by CUP1-CRS5-null cells when exposed to combined Zn/Cu, as it does the mouse MT1 Zn-thionein, but not Cup1. The detailed characterization of Crs5 in vivo and in vitro Zn(II)-, Cd(II)- and Cu(I)-binding abilities fully supports its resemblance to mammalian MTs. Hence, Crs5 exhibits a good divalent metal-binding ability, yielding homometallic, highly chiral and stable Zn and Cd complexes when expressed in media enriched with these metal ions. In Cu-supplemented cultures, heterometallic Zn,Cu complexes are recovered, unless aeration is kept to a minimum. These features define a Crs5 dual metal-binding behaviour that is significantly closer to Zn-thioneins than to Cu-thioneins. Protein sequence similarities fully support these findings. Overall, a Crs5 function in global metal cell homeostasis, based on its Zn-binding features, is glimpsed. The comparative evaluation of Crs5 in the framework of MT functional differentiation and evolution allows its consideration as a representative of the primeval eukaryotic forms that progressively evolved to give rise to the Zn-thionein lineage.
Pagani
Ayelen
A
Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
Villarreal
Laura
L
Capdevila
Mercè
M
Atrian
Sílvia
S
D003300:Copper / Q000378:metabolism* / Q000633:toxicity; D015966:Gene Expression Regulation, Fungal; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism* / Q000633:toxicity
C089939:CRS5 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D003300:Copper; D008668:Metallothionein; D015032:Zinc