Position-Specific contribution of interface tryptophans on membrane protein energetics.
Biochim Biophys Acta Biomembr
; 1860(2): 451-457, 2018 Feb.
Article
em En
| MEDLINE
| ID: mdl-29128310
ABSTRACT
Interface tryptophans are key residues that facilitate the folding and stability of membrane proteins. Escherichia coli OmpX possesses two unique interface tryptophans, namely Trp76, which is present at the interface and is solvent-exposed, and Trp140, which is relatively more lipid solvated than Trp76 in symmetric lipid membranes. Here, we address the requirement for tryptophan and the consequences of aromatic amino acid substitutions on the folding and stability of OmpX. Using spectroscopic measurements of OmpX-Trp/Tyr/Phe mutants, we show that the specific mutation W76âY allows barrel assembly >1.5-fold faster than native OmpX, and increases stability by ~0.4kcalmol-1. In contrast, mutating W140âF/Y lowers OmpX thermodynamic stability by ~0.4kcalmol-1, without affecting the folding kinetics. We conclude that the stabilizing effect of tryptophan at the membrane interface can be position-and local environment-specific. We propose that the thermodynamic contributions for interface residues be interpreted with caution.
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Texto completo:
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Termodinâmica
/
Proteínas da Membrana Bacteriana Externa
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Triptofano
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Proteínas de Escherichia coli
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Hidrolases
Idioma:
En
Ano de publicação:
2018
Tipo de documento:
Article