title: Structural and functional studies of vertebrate metallothioneins: cross-talk between domains in the absence of physical contact.
abstract: In previous studies, we showed that the chemical and dynamic properties of fish and mouse MTs (metallothioneins) present a number of distinctive differences linked to their primary structures, and that phylogenetic relationships of mammal and fish MTs correlate with their three-dimensional structures. The different behaviours of MTs may also be linked to the interaction between their two domains. In the present study, we have compared the physicochemical properties of the isolated recombinant domains constituting Notothenia coriiceps and mouse MTs, and compared them with those of the corresponding whole MTs. NMR spectra of the separated domains of N. coriiceps are almost superimposable on those of the parent MT, suggesting an apparent lack of interaction between the two domains in the protein. However, certain dynamic and physicochemical features of the isolated domains are unlike those of the whole protein. In particular, the temperature-induced changes in the chiroptical properties, thiol reactivity of the Zn-MT domains and the Zn2+/Cd2+ rate of exchange are different for the two domains and with respect to the whole protein. Taken together, these results provide a strong argument in favour of the interaction of the two domains in the MT molecule, in spite of the elusive evidence provided by the structural analyses.
authors.affiliation: CNR, Institute of Protein Biochemistry, via P. Castellino 111 I 80131 Naples, Italy.
authors.forename: Clemente
authors.initials: C
authors.lastname: Capasso
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Carginale
authors.forename: Orlando
authors.initials: O
authors.lastname: Crescenzi
authors.forename: Daniela
authors.initials: D
authors.lastname: Di Maro
authors.forename: Roberta
authors.initials: R
authors.lastname: Spadaccini
authors.forename: Piero Andrea
authors.initials: PA
authors.lastname: Temussi
authors.forename: Elio
authors.initials: E
authors.lastname: Parisi
mesh_terms: D000818:Animals; D001692:Biological Transport; D002104:Cadmium / Q000378:metabolism; D002942:Circular Dichroism; D004228:Dithionitrobenzoic Acid; D005399:Fishes; D005978:Glutathione / Q000378:metabolism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008668:Metallothionein / Q000737:chemistry* / Q000378:metabolism*; D051379:Mice; D010084:Oxidation-Reduction; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins; D013045:Species Specificity; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013696:Temperature; D015032:Zinc / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D013438:Sulfhydryl Compounds; D002104:Cadmium; D008668:Metallothionein; D004228:Dithionitrobenzoic Acid; D005978:Glutathione; D015032:Zinc