Active site serine-193 modulates activity of human aromatic amino acid decarboxylase

Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved..

Aromatic amino acid decarboxylase is a pyridoxal 5'-phosphate-dependent enzyme responsible for the synthesis of the neurotransmitters, dopamine and serotonin. Here, by a combination of bioinformatic predictions and analyses, phosphorylation assays, spectroscopic investigations and activity measurements, we determined that Ser-193, a conserved residue located at the active site, can be phosphorylated, increasing catalytic efficiency. In order to determine the molecular basis for this functional improvement, we determined the structural and kinetic properties of the site-directed variants S193A, S193D and S193E. While S193A retains 27% of the catalytic efficiency of wild-type, the two acidic side chain variants are impaired in catalysis with efficiencies of about 0.15% with respect to the wild-type. Thus, even if located at the active site, Ser-193 is not essential for enzyme activity. We advance the idea that this residue is fundamental for the correct architecture of the active site in terms of network of interactions triggering catalysis. This role has been compared with the properties of the Ser-194 of the highly homologous enzyme histidine decarboxylase whose catalytic loop is visible in the spatial structure, allowing us to propose the validation for the effect of the phosphorylation. The effect could be interesting for AADC deficiency, a rare monogenic disease, whose broad clinical phenotype could be also related to post translational AADC modifications.

Medienart:

E-Artikel

Erscheinungsjahr:

2023

Erschienen:

2023

Enthalten in:

Zur Gesamtaufnahme - volume:679

Enthalten in:

Biochemical and biophysical research communications - 679(2023) vom: 30. Okt., Seite 6-14

Sprache:

Englisch

Beteiligte Personen:

Bisello, Giovanni [VerfasserIn]
Rossignoli, Giada [VerfasserIn]
Choi, Sarah [VerfasserIn]
Phillips, Robert S [VerfasserIn]
Bertoldi, Mariarita [VerfasserIn]

Links:

Volltext

Themen:

Aromatic amino acid decarboxylase
Journal Article
Phosphorylation
Protein chemistry
Pyridoxal 5′-phosphate
Site-directed mutagenesis

Anmerkungen:

Date Revised 29.09.2023

published: Print-Electronic

Citation Status Publisher

doi:

10.1016/j.bbrc.2023.08.049

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM361496958