Functional and structural consequences of a novel point mutation in the CYP21A2 gene causing congenital adrenal hyperplasia: Potential relevance of helix C for P450 oxidoreductase-21-hydroxylase interaction

Felix G. Riepe, Olaf Hiort, Joachim Grötzinger, Wolfgang G. Sippell, Nils Krone, Paul Martin Holterhus

15 Zitate (Scopus)

Abstract

Background: Congenital adrenal hyperplasia is caused by insufficient adrenal steroid biosynthesis due to impaired steroidogenic enzymes. The majority of patients suffer from deficiency of 21-hydroxylase (CYP21) coded by the CYP21A2 gene. Objective: Our objective was to study the functional and structural consequences of the novel CYP21A2 missense mutation c.364A > C (K121Q) detected in a female patient with nonclassical 21-hydroxylase deficiency. The patient was compound heterozygous for the novel K121Q mutation and the mild P453S mutation. Results: In vitro expression analysis of the mutant K121Q enzyme in transiently transfected COS-7 cells revealed reduced CYP21 activity of 14.0 ± 5% for the conversion of 17-hydroxyprogesterone and 19.5 ± 4% for the conversion of progesterone. K121 is located on helix C in the CYP21 protein, which is part of the heme coordinating system. In addition, helix C is involved in the interaction with the electron-providing enzyme P450 oxidoreductase. Protein modeling revealed that the substitution of glutamine for the basic aminoacid lysine introduces an electrostatic change on the surface of CYP21 and may additionally change heme coordination. We hypothesize that the electron flux between P450 oxidoreductase and CYP21 is impaired and, moreover, that substrate affinity is altered due to heme dislocation with K121Q. Conclusion: Both the interaction of P450 oxidoreductase and CYP21 as well as heme coordination are likely to be disturbed due to the K121Q mutation. Our data exemplify how the combination of in vitro expression and structural protein analysis provide novel insights into molecular mechanisms of reduced CYP21 activity, eventually explaining the patient's phenotype.

OriginalspracheEnglisch
ZeitschriftJournal of Clinical Endocrinology and Metabolism
Jahrgang93
Ausgabenummer7
Seiten (von - bis)2891-2895
Seitenumfang5
ISSN0021-972X
DOIs
PublikationsstatusVeröffentlicht - 07.2008

Strategische Forschungsbereiche und Zentren

  • Forschungsschwerpunkt: Gehirn, Hormone, Verhalten - Center for Brain, Behavior and Metabolism (CBBM)

Fingerprint

Untersuchen Sie die Forschungsthemen von „Functional and structural consequences of a novel point mutation in the CYP21A2 gene causing congenital adrenal hyperplasia: Potential relevance of helix C for P450 oxidoreductase-21-hydroxylase interaction“. Zusammen bilden sie einen einzigartigen Fingerprint.

Zitieren