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Impact of naturally occurring serine/cysteine variations on the structure and function of Pseudomonas metallothioneins


Habjanič, Jelena; Chesnov, Serge; Zerbe, Oliver; Freisinger, Eva (2020). Impact of naturally occurring serine/cysteine variations on the structure and function of Pseudomonas metallothioneins. Metallomics, 12(1):23-33.

Abstract

Metallothioneins (MTs), small cysteine-rich metal-binding proteins, support the viability of organisms under normal physiological conditions and help them to respond to different environmental stressors. Upon metal coordination (e.g. ZnII, CdII, CuI) they form characteristic polynuclear metal–thiolate clusters that are known for their high thermodynamic stability and kinetic lability. However, despite numerous studies, it is still not understood how MTs modulate their metal-binding properties. Pseudomonas MTs are an emerging subclass of bacterial MTs, distinct for their high number of His residues and for several unique features such as an intrinsically disordered long C-terminal tail and multiple variations in the number and nature of coordinating amino acids. These variations might provide the bacteria with a functional advantage derived from evolutionary adaptation to heterogeneous environments. Nearly 90% of the known Pseudomonas MT sequences feature a central YC[C with combining low line]xxC motif, that is altered to YC[S with combining low line]xxC in the rest. We demonstrate that the additional Cys residue serves as a coordinating ligand without influencing the metal-binding capacity, the overall metal-binding stability or the structure. However, the additional ligand changes intra-cluster dynamics and, as a consequence, modulates metal transfer reactions that could be functionally advantageous in vivo.

Abstract

Metallothioneins (MTs), small cysteine-rich metal-binding proteins, support the viability of organisms under normal physiological conditions and help them to respond to different environmental stressors. Upon metal coordination (e.g. ZnII, CdII, CuI) they form characteristic polynuclear metal–thiolate clusters that are known for their high thermodynamic stability and kinetic lability. However, despite numerous studies, it is still not understood how MTs modulate their metal-binding properties. Pseudomonas MTs are an emerging subclass of bacterial MTs, distinct for their high number of His residues and for several unique features such as an intrinsically disordered long C-terminal tail and multiple variations in the number and nature of coordinating amino acids. These variations might provide the bacteria with a functional advantage derived from evolutionary adaptation to heterogeneous environments. Nearly 90% of the known Pseudomonas MT sequences feature a central YC[C with combining low line]xxC motif, that is altered to YC[S with combining low line]xxC in the rest. We demonstrate that the additional Cys residue serves as a coordinating ligand without influencing the metal-binding capacity, the overall metal-binding stability or the structure. However, the additional ligand changes intra-cluster dynamics and, as a consequence, modulates metal transfer reactions that could be functionally advantageous in vivo.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Uncontrolled Keywords:Biophysics, Biochemistry, Chemistry (miscellaneous), Cadmium, Zinc, Biomaterials, metallothionine
Language:English
Date:1 January 2020
Deposited On:21 Feb 2020 06:37
Last Modified:22 Feb 2020 04:16
Publisher:Royal Society of Chemistry
ISSN:1756-5901
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1039/c9mt00213h

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