Frequent sequence variants of human glycine N-acyltransferase (GLYAT) and inborn errors of metabolism

Glycine conjugation is an important phase II reaction and represents a central detoxification pathway which is essential for the recycling of free coenzyme A. Only few sequence variants have been reported in the human GLYAT gene and only two studies have overexpressed the human protein in bacterial systems and partially characterized it. This has prompted us to study the wild-type enzyme and two sequence variants not only in the E. coli strain Origami 2(DE3), but also to overexpress GLYAT in HEK293 cells, a human-derived cell line. Following purification of the recombinant proteins from E. coli the wild-type GLYAT protein and sequence variants, p.(Gln61Leu) yielded decreased specific activity than the wildtype enzyme, while specific activity of p.(Asn156Ser) activity of the latter variant was somewhat increased. KM values were similar for the three forms of GLYAT overexpressed in bacteria and for the wild-type enzyme overexpressed in HEK293 cells. Localization studies demonstrated intramitochondrial localization of human wild-type GLYAT, conjugated with eGFP, in the HEK293 cells. As p.(Gln61Leu) does not only impair GLYAT activity in vitro, but is of high prevalence in a Caucasian Afrikaner cohort in South Africa, potential pharmacogenetic implications, warrant further studies of GLYAT. ? 2021 Elsevier B.V. and Soci?t? Fran?aise de Biochimie et Biologie Mol?culaire (SFBBM). All rights

Automated summary

Glycine conjugation is a critical detoxification pathway for recycling coenzyme A in humans. Study of wild-type enzyme and sequence variants revealed differences in specific activity, with potential pharmacogenetic implications for the prevalent p.(Gln61Leu) variant. Further research on the genetic and functional implications is recommended.