Unravelling the Complex Denaturant and Thermal-Induced Unfolding Equilibria of Human Phenylalanine Hydroxylase

Conde-Giménez, María ; Sancho, Javier (Universidad de Zaragoza)

Resumen: Human phenylalanine hydroxylase (PAH) is a metabolic enzyme involved in the catabolism of L-Phe in liver. Loss of conformational stability and decreased enzymatic activity in PAH variants result in the autosomal recessive disorder phenylketonuria (PKU), characterized by developmental and psychological problems if not treated early. One current therapeutic approach to treat PKU is based on pharmacological chaperones (PCs), small molecules that can displace the folding equilibrium of unstable PAH variants toward the native state, thereby rescuing the physiological function of the enzyme. Understanding the PAH folding equilibrium is essential to develop new PCs for different forms of the disease. We investigate here the urea and the thermal-induced denaturation of full-length PAH and of a truncated form lacking the regulatory and the tetramerization domains. For either protein construction, two distinct transitions are seen in chemical denaturation followed by fluorescence emission, indicating the accumulation of equilibrium unfolding intermediates where the catalytic domains are partly unfolded and dissociated from each other. According to analytical centrifugation, the chemical denaturation intermediates of either construction are not well-defined species but highly polydisperse ensembles of protein aggregates. On the other hand, each protein construction similarly shows two transitions in thermal denaturation measured by fluorescence or differential scanning calorimetry, also indicating the accumulation of equilibrium unfolding intermediates. The similar temperatures of mid denaturation of the two constructions, together with their apparent lack of response to protein concentration, indicate the catalytic domains are unfolded in the full-length PAH thermal intermediate, where they remain associated. That the catalytic domain unfolds in the first thermal transition is relevant for the choice of PCs identified in high throughput screening of chemical libraries using differential scanning fluorimetry.

Idioma: Inglés

DOI: 10.3390/ijms22126539

Año: 2021

Publicado en: International Journal of Molecular Sciences 22, 12 (2021), 22126539 [17 pp.]
ISSN: 1661-6596

Factor impacto JCR: 6.208 (2021)

Categ. JCR: BIOCHEMISTRY & MOLECULAR BIOLOGY rank: 69 / 297 = 0.232 (2021) - Q1 - T1
Categ. JCR: CHEMISTRY, MULTIDISCIPLINARY rank: 50 / 180 = 0.278 (2021) - Q2 - T1

Factor impacto CITESCORE: 6.9 - Computer Science (Q1) - Chemical Engineering (Q1) - Medicine (Q1) - Biochemistry, Genetics and Molecular Biology (Q2)

Factor impacto SCIMAGO: 1.176 - Computer Science Applications (Q1) - Inorganic Chemistry (Q1) - Spectroscopy (Q1) - Organic Chemistry (Q1) - Physical and Theoretical Chemistry (Q1) - Molecular Biology (Q1)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E45-17R
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PID2019-107293GB-I00
Financiación: info:eu-repo/grantAgreement/ES/MINECO/BFU2016-78232-P

Tipo y forma: Article (Published version)

Área (Departamento): Área Bioquímica y Biolog.Mole. (Dpto. Bioq.Biolog.Mol. Celular)