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A novel pathological variant of the acetyltransferase NAA10 causes disabilities

N-terminal acetylation is a very common protein modification and NAA10 is the major responsible enzyme in human cells. Here we found a novel pathological NAA10 variant, NAA10 p. (R83H), in two boys with developmental delay and intellectual disabilities.

Impaired function of the NAA10 R83H variant
The pathological varianten NAA10 R83H has a reduced enzymatic activity (a+c). Structural model of NAA10 where the altered amino acid (Arg83His) labelled in red is in direct contact with Acetyl Coenzyme A which donates the Acetyl group in the reaction (b). Arg83 is very conserved in NAA10 in different species supporting that the R83H alteration may be detrimental for protein function (d)
Photo:
Rasmus Ree et al.

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In collaboration with clinicians at the Odense University Hospital in Denmark andÌýTemple Street Children’s Hospital, Dublin, Ireland,Ìýmaster student Anni Sofie Geithus and researcherÌýRasmus Ree from theÌýArnesen lab found a novelÌýpathological variantÌýof NAA10. Two boys with overlapping phenotypes were independently examined in Denmark and Ireland, and by exome sequencing it was found that they both harbor a novel variant of the NAA10 gene. The NAA10 protein forms theÌýNatA complex togetherÌýwith NAA15, and is responsible for acetylating thousands of proteins in human cells.ÌýThe NAT-group atÌýÐÒÔË·Éͧ¼Æ»® was then contacted, andÌýGeithus andÌýRee found that this special variant of NAA10 exhibited a very reduced catalytic activity. This is most likely caused by the fact that Arg83 is in direct contact with the first substrate of the reaction, Acetyl Coenzyme A, and a change toÌýHis83Ìýmay disrupt this interaction.

This study sheds light on the physiological impact ofÌýprotein N-terminal acetylation in humans, since these two boys were found to have a number of fenotypes including developmental delay, intellectual disabilities, ADHD like behavior, epilepsy, and cardiac anomalies.

The study was recently published and can be read .ÌýÌý

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