Header

UZH-Logo

Maintenance Infos

Functional Characterization and Categorization of Missense Mutations that Cause Methylmalonyl-CoA Mutase (MUT) Deficiency


Forny, Patrick; Froese, D Sean; Suormala, Terttu; Yue, Wyatt W; Baumgartner, Matthias R (2014). Functional Characterization and Categorization of Missense Mutations that Cause Methylmalonyl-CoA Mutase (MUT) Deficiency. Human Mutation, 35(12):1449-1458.

Abstract

Methylmalonyl-CoA mutase (MUT) is an essential enzyme in propionate catabolism that requires adenosylcobalamin as a cofactor. Almost 250 inherited mutations in the MUT gene are known to cause the devastating disorder methylmalonic aciduria; however, the mechanism of dysfunction of these mutations, more than half of which are missense changes, has not been thoroughly investigated. Here, we examined 23 patient missense mutations covering a spectrum of exonic/structural regions, clinical phenotypes, and ethnic populations in order to determine their influence on protein stability, using two recombinant expression systems and a thermostability assay, and enzymatic function by measuring MUT activity and affinity for its cofactor and substrate. Our data stratify MUT missense mutations into categories of biochemical defects, including (1) reduced protein level due to misfolding, (2) increased thermolability, (3) impaired enzyme activity, and (4) reduced cofactor response in substrate turnover. We further demonstrate the stabilization of wild-type and thermolabile mutants by chemical chaperones in vitro and in bacterial cells. This in-depth mutation study illustrates the tools available for MUT enzyme characterization, guides future categorization of further missense mutations, and supports the development of alternative, chaperone-based therapy for patients not responding to current treatment.

Abstract

Methylmalonyl-CoA mutase (MUT) is an essential enzyme in propionate catabolism that requires adenosylcobalamin as a cofactor. Almost 250 inherited mutations in the MUT gene are known to cause the devastating disorder methylmalonic aciduria; however, the mechanism of dysfunction of these mutations, more than half of which are missense changes, has not been thoroughly investigated. Here, we examined 23 patient missense mutations covering a spectrum of exonic/structural regions, clinical phenotypes, and ethnic populations in order to determine their influence on protein stability, using two recombinant expression systems and a thermostability assay, and enzymatic function by measuring MUT activity and affinity for its cofactor and substrate. Our data stratify MUT missense mutations into categories of biochemical defects, including (1) reduced protein level due to misfolding, (2) increased thermolability, (3) impaired enzyme activity, and (4) reduced cofactor response in substrate turnover. We further demonstrate the stabilization of wild-type and thermolabile mutants by chemical chaperones in vitro and in bacterial cells. This in-depth mutation study illustrates the tools available for MUT enzyme characterization, guides future categorization of further missense mutations, and supports the development of alternative, chaperone-based therapy for patients not responding to current treatment.

Statistics

Citations

8 citations in Web of Science®
9 citations in Scopus®
Google Scholar™

Altmetrics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Children's Hospital Zurich > Medical Clinic
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:December 2014
Deposited On:30 Dec 2014 15:42
Last Modified:05 Apr 2016 18:42
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:1059-7794
Publisher DOI:https://doi.org/10.1002/humu.22633
PubMed ID:25125334

Download

Full text not available from this repository.
View at publisher