Engineering potassium activation into biosynthetic thiolase.
Biochem J
; 478(15): 3047-3062, 2021 08 13.
Article
em En
| MEDLINE
| ID: mdl-34338286
ABSTRACT
Activation of enzymes by monovalent cations (M+) is a widespread phenomenon in biology. Despite this, there are few structure-based studies describing the underlying molecular details. Thiolases are a ubiquitous and highly conserved family of enzymes containing both K+-activated and K+-independent members. Guided by structures of naturally occurring K+-activated thiolases, we have used a structure-based approach to engineer K+-activation into a K+-independent thiolase. To our knowledge, this is the first demonstration of engineering K+-activation into an enzyme, showing the malleability of proteins to accommodate M+ ions as allosteric regulators. We show that a few protein structural features encode K+-activation in this class of enzyme. Specifically, two residues near the substrate-binding site are sufficient for K+-activation A tyrosine residue is required to complete the K+ coordination sphere, and a glutamate residue provides a compensating charge for the bound K+ ion. Further to these, a distal residue is important for positioning a K+-coordinating water molecule that forms a direct hydrogen bond to the substrate. The stability of a cation-π interaction between a positively charged residue and the substrate is determined by the conformation of the loop surrounding the substrate-binding site. Our results suggest that this cation-π interaction effectively overrides K+-activation, and is, therefore, destabilised in K+-activated thiolases. Evolutionary conservation of these amino acids provides a promising signature sequence for predicting K+-activation in thiolases. Together, our structural, biochemical and bioinformatic work provide important mechanistic insights into how enzymes can be allosterically activated by M+ ions.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Acetil-CoA C-Acetiltransferase
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Potássio
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Proteínas de Bactérias
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Zoogloea
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Cátions Monovalentes
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Ativação Enzimática
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2021
Tipo de documento:
Article