Metallobiological Necklaces: Mass Spectrometric and Molecular Modeling Study of Metallation in Concatenated Domains of Metallothionein

Chan, J., Huang, Z., Watt, I., Kille, Peter ORCID: https://orcid.org/0000-0001-6023-5221 and Stillman, M. 2008. Metallobiological Necklaces: Mass Spectrometric and Molecular Modeling Study of Metallation in Concatenated Domains of Metallothionein. Chemistry - A European Journal 14 (25) , pp. 7579-7593. 10.1002/chem.200800787

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Abstract

The ubiquitous protein metallothionein (MT) has proven to be a major player not only in the homeostasis of CuI and ZnII, but also binds all the Group 11 and 12 metals. Metallothioneins are characterised by the presence of numerous cys-x-cys and cys–cys motifs in the sequence and are found naturally with either one domain or two, linked, metal-binding domains. The use of chains of these metal–thiolate domains offers the possibility of creating chemically tuneable and, therefore, chemically dependent electrochemical or photochemical surface modifiers or as nanomachinery with nanomechanical properties. In this work, the metal-binding properties of the Cd4-containing domain of α-rhMT1a assembled into chains of two and three concatenated domains, that is, “necklaces”, have been studied by spectrometric techniques, and the interactions within the structures modelled and interpreted by using molecular dynamics. These chains are metallated with 4, 8 or 12 CdII ions to the 11, 22, and 33 cysteinyl sulfur atoms in the α-rhMT1a, αα-rhMT1a, and ααα-rhMT1a proteins, respectively. The effect of pH on the folding of each protein was studied by ESI-MS and optical spectroscopy. MM3/MD simulations were carried out over a period of up to 500 ps by using force-field parameters based on the reported structural data. These calculations provide novel information about the motion of the clustered metallated, partially demetallated, and metal-free peptide chains, with special interest in the region of the metal-binding site. The MD energy/time trajectory conformations show for the first time the flexibility of the metal–sulfur clusters and the bound amino acid chains. We report unexpected and very different sizes for the metallated and demetallated proteins from the combination of experimental data, with molecular dynamics simulations.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry Biosciences
Uncontrolled Keywords:	cadmium; mass spectrometry; metallothionein; molecular dynamics; molecular modeling
Publisher:	Wiley-Blackwell
ISSN:	1521-3765
Last Modified:	17 Oct 2022 09:50
URI:	https://orca.cardiff.ac.uk/id/eprint/5891

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