The mutations G170R and I244T are the most common disease cause in primary hyperoxaluria
type I (PH1). These mutations cause the misfolding of the AGT protein in the minor allele
AGT-LM that contains the P11L polymorphism, which may affect the folding of the N-terminal
segment (NTT-AGT). The NTT-AGT is phosphorylated at T9, although the role of this event in PH1
is unknown. In this work, phosphorylation of T9 was mimicked by introducing the T9E mutation
in the NTT-AGT peptide and the full-length protein. The NTT-AGT conformational landscape was
studied by circular dichroism, NMR, and statistical mechanical methods. Functional and stability
effects on the full-length AGT protein were characterized by spectroscopic methods. The T9E and
P11L mutations together reshaped the conformational landscape of the isolated NTT-AGT peptide
by stabilizing ordered conformations. In the context of the full-length AGT protein, the T9E mutation
had no effect on the overall AGT function or conformation, but enhanced aggregation of
the minor allele (LM) protein and synergized with the mutations G170R and I244T. Our findings
indicate that phosphorylation of T9 may affect the conformation of the NTT-AGT and synergize with
PH1-causing mutations to promote aggregation in a genotype-specific manner. Phosphorylation
should be considered a novel regulatory mechanism in PH1 pathogenesis.Comunidad Valenciana CIAICO/2021/135
AULA FUNCANIS-UGRERDF/Spanish Ministry of Science, Innovation, and Universities-State Research Agency RTI2018-096246-B-I00Junta de Andalucia P18-RT-2413
ERDF/ Counseling of Economic transformation, Industry, Knowledge, and Universities B-BIO-84-UGR2
