Salt Dependence Conformational Stability of the Dimeric SAM Domain of MAPKKK Ste11 from Budding Yeast: A Native-State H/D Exchange NMR Study.
Biochemistry
; 59(31): 2849-2858, 2020 08 11.
Article
em En
| MEDLINE
| ID: mdl-32667811
ABSTRACT
The sterile α motif, also called the SAM domain, is known to form homo or heterocomplexes that modulate diverse biological functions through the regulation of specific protein-protein interactions. The MAPK pathway of budding yeast Saccharomyces cerevisiae is comprised of a three-tier kinase system akin to mammals. The MAPKKK Ste11 protein of yeast contains a homodimer SAM domain, which is critical for transmitting cues to the downstream kinases. The structural stability of the dimeric Ste11 SAM is maintained by hydrophobic and ionic interactions at the interfacial amino acids. The urea-induced equilibrium-unfolding process of the Ste11 SAM domain is cooperative without evidence of any intermediate states. The native-state H/D exchange under subdenaturing conditions is a useful method for the detection of intermediate states of proteins. In the present study, we investigated the effect of ionic strength on the conformational stability of the dimer using the H/D exchange experiments. The hydrogen exchange behavior of the Ste11 dimer under physiological salt concentrations reveals two partially unfolded metastable intermediate states, which may be generated by a sequential and cooperative unfolding of the five helices present in the domain. These intermediates appear to be significant for the reversible unfolding kinetics via hydrophobic collapse. In contrast, higher ionic concentrations eliminate this cooperative interactions that stabilize the pairs of helices.
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Base de dados:
MEDLINE
Assunto principal:
Cloreto de Sódio
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Modelos Moleculares
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Ressonância Magnética Nuclear Biomolecular
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MAP Quinase Quinase Quinases
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Proteínas de Saccharomyces cerevisiae
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Medição da Troca de Deutério
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Multimerização Proteica
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article