Biochemical analyses and molecular modeling explain the functional loss of 17β-hydroxysteroid dehydrogenase 3 mutant G133R in three Tunisian patients with 46, XY Disorders of Sex Development
| Autor: | Neila Belguith, Faiza Fakhfakh, Alex Odermatt, Bochra Ben Rhouma, Christoph P. Sager, Maria Tsachaki, Roger T. Engeli, Leila Keskes, Julia Birk |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Male
Models Molecular 0301 basic medicine 17-Hydroxysteroid Dehydrogenases Adolescent Endocrinology Diabetes and Metabolism Molecular Sequence Data Clinical Biochemistry Nonsense mutation Mutant 030209 endocrinology & metabolism Dehydrogenase Biology Endoplasmic Reticulum Biochemistry Conserved sequence 03 medical and health sciences 0302 clinical medicine Endocrinology Humans Missense mutation Amino Acid Sequence Hydroxysteroid dehydrogenase Child Molecular Biology Conserved Sequence chemistry.chemical_classification Cofactor binding Disorder of Sex Development 46 XY Cell Biology Molecular biology HEK293 Cells 030104 developmental biology Enzyme Amino Acid Substitution chemistry Mutation Mutagenesis Site-Directed Molecular Medicine Female NADP |
| Zdroj: | The Journal of Steroid Biochemistry and Molecular Biology. 155:147-154 |
| ISSN: | 0960-0760 |
| DOI: | 10.1016/j.jsbmb.2015.10.023 |
| Popis: | Mutations in the HSD17B3 gene resulting in 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) deficiency cause 46, XY Disorders of Sex Development (46, XY DSD). Approximately 40 different mutations in HSD17B3 have been reported; only few mutant enzymes have been mechanistically investigated. Here, we report novel compound heterozygous mutations in HSD17B3, composed of the nonsense mutation C206X and the missense mutation G133R, in three Tunisian patients from two non-consanguineous families. Mutants C206X and G133R were constructed by site-directed mutagenesis and expressed in HEK-293 cells. The truncated C206X enzyme, lacking part of the substrate binding pocket, was moderately expressed and completely lost its enzymatic activity. Wild-type 17β-HSD3 and mutant G133R showed comparable expression levels and intracellular localization. The conversion of Δ4-androstene-3,17-dione (androstenedione) to testosterone was almost completely abolished for mutant G133R compared with wild-type 17β-HSD3. To obtain further mechanistic insight, G133 was mutated to alanine, phenylalanine and glutamine. G133Q and G133F were almost completely inactive, whereas G133A displayed about 70% of wild-type activity. Sequence analysis revealed that G133 on 17β-HSD3 is located in a motif highly conserved in 17β-HSDs and other short-chain dehydrogenase/reductase (SDR) enzymes. A homology model of 17β-HSD3 predicted that arginine or any other bulky residue at position 133 causes steric hindrance of cofactor NADPH binding, whereas substrate binding seems to be unaffected. The results indicate an essential role of G133 in the arrangement of the cofactor binding pocket, thus explaining the loss-of-function of 17β-HSD3 mutant G133R in the patients investigated. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect