A novel Kleefstra syndrome-associated variant that affects the conserved TPLX motif within the ankyrin repeat of EHMT1 leads to abnormal protein folding

Patrick R. Blackburn, Alexander Tischer, Michael T. Zimmermann, Jennifer L. Kemppainen, Sujatha Sastry, Amy E. Knight Johnson, Margot A. Cousin, Nicole J. Boczek, Gavin Oliver, Vinod K. Misra, Ralitza M Gavrilova, Gwen Lomberk, Matthew T Auton, Raul Urrutia, Eric W Klee

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Kleefstra syndrome (KS) (Mendelian Inheritance in Man (MIM) no. 610253), also known as 9q34 deletion syndrome, is an autosomal dominant disorder caused by haploinsufficiency of euchromatic histone methyltransferase-1 (EHMT1). The clinical phenotype of KS includes moderate to severe intellectual disability with absent speech, hypotonia, brachycephaly, congenital heart defects, and dysmorphic facial features with hypertelorism, synophrys, macroglossia, protruding tongue, and prognathism. Only a few cases of de novo missense mutations in EHMT1 giving rise to KS have been described. However, some EHMT1 variants have been described in individuals presenting with autism spectrum disorder or mild intellectual disability, suggesting that the phenotypic spectrum resulting from EHMT1 alterations may be quite broad. In this report, we describe two unrelated patients with complex medical histories consistent with KS in whom next generation sequencing identified the same novel c.2426C>T (p.P809L) missense variant in EHMT1. To examine the functional significance of this novel variant, we performed molecular dynamics simulations of the wild type and p.P809L variant, which predicted that the latter would have a propensity to misfold, leading to abnormal histone mark binding. Recombinant EHMT1 p.P809L was also studied using far UV circular dichroism spectroscopy and intrinsic protein fluorescence. These functional studies confirmed the model-based hypotheses and provided evidence for protein misfolding and aberrant target recognition as the underlying pathogenic mechanism for this novel KS-associated variant. This is the first report to suggest that missense variants in EHMT1 that lead to protein misfolding and disrupted histone mark binding can lead to KS.

Original languageEnglish (US)
Pages (from-to)3866-3876
Number of pages11
JournalJournal of Biological Chemistry
Volume292
Issue number9
DOIs
StatePublished - Mar 3 2017

Fingerprint

Ankyrin Repeat
Protein folding
Protein Folding
Histone Code
Intellectual Disability
Histones
Macroglossia
Prognathism
Hypertelorism
Circular dichroism spectroscopy
Haploinsufficiency
Craniosynostoses
Proteins
Muscle Hypotonia
Congenital Heart Defects
Missense Mutation
Molecular Dynamics Simulation
Circular Dichroism
Kleefstra Syndrome
histone methyltransferase

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

A novel Kleefstra syndrome-associated variant that affects the conserved TPLX motif within the ankyrin repeat of EHMT1 leads to abnormal protein folding. / Blackburn, Patrick R.; Tischer, Alexander; Zimmermann, Michael T.; Kemppainen, Jennifer L.; Sastry, Sujatha; Knight Johnson, Amy E.; Cousin, Margot A.; Boczek, Nicole J.; Oliver, Gavin; Misra, Vinod K.; Gavrilova, Ralitza M; Lomberk, Gwen; Auton, Matthew T; Urrutia, Raul; Klee, Eric W.

In: Journal of Biological Chemistry, Vol. 292, No. 9, 03.03.2017, p. 3866-3876.

Research output: Contribution to journalArticle

Blackburn, PR, Tischer, A, Zimmermann, MT, Kemppainen, JL, Sastry, S, Knight Johnson, AE, Cousin, MA, Boczek, NJ, Oliver, G, Misra, VK, Gavrilova, RM, Lomberk, G, Auton, MT, Urrutia, R & Klee, EW 2017, 'A novel Kleefstra syndrome-associated variant that affects the conserved TPLX motif within the ankyrin repeat of EHMT1 leads to abnormal protein folding', Journal of Biological Chemistry, vol. 292, no. 9, pp. 3866-3876. https://doi.org/10.1074/jbc.M116.770545
Blackburn, Patrick R. ; Tischer, Alexander ; Zimmermann, Michael T. ; Kemppainen, Jennifer L. ; Sastry, Sujatha ; Knight Johnson, Amy E. ; Cousin, Margot A. ; Boczek, Nicole J. ; Oliver, Gavin ; Misra, Vinod K. ; Gavrilova, Ralitza M ; Lomberk, Gwen ; Auton, Matthew T ; Urrutia, Raul ; Klee, Eric W. / A novel Kleefstra syndrome-associated variant that affects the conserved TPLX motif within the ankyrin repeat of EHMT1 leads to abnormal protein folding. In: Journal of Biological Chemistry. 2017 ; Vol. 292, No. 9. pp. 3866-3876.
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abstract = "Kleefstra syndrome (KS) (Mendelian Inheritance in Man (MIM) no. 610253), also known as 9q34 deletion syndrome, is an autosomal dominant disorder caused by haploinsufficiency of euchromatic histone methyltransferase-1 (EHMT1). The clinical phenotype of KS includes moderate to severe intellectual disability with absent speech, hypotonia, brachycephaly, congenital heart defects, and dysmorphic facial features with hypertelorism, synophrys, macroglossia, protruding tongue, and prognathism. Only a few cases of de novo missense mutations in EHMT1 giving rise to KS have been described. However, some EHMT1 variants have been described in individuals presenting with autism spectrum disorder or mild intellectual disability, suggesting that the phenotypic spectrum resulting from EHMT1 alterations may be quite broad. In this report, we describe two unrelated patients with complex medical histories consistent with KS in whom next generation sequencing identified the same novel c.2426C>T (p.P809L) missense variant in EHMT1. To examine the functional significance of this novel variant, we performed molecular dynamics simulations of the wild type and p.P809L variant, which predicted that the latter would have a propensity to misfold, leading to abnormal histone mark binding. Recombinant EHMT1 p.P809L was also studied using far UV circular dichroism spectroscopy and intrinsic protein fluorescence. These functional studies confirmed the model-based hypotheses and provided evidence for protein misfolding and aberrant target recognition as the underlying pathogenic mechanism for this novel KS-associated variant. This is the first report to suggest that missense variants in EHMT1 that lead to protein misfolding and disrupted histone mark binding can lead to KS.",
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T1 - A novel Kleefstra syndrome-associated variant that affects the conserved TPLX motif within the ankyrin repeat of EHMT1 leads to abnormal protein folding

AU - Blackburn, Patrick R.

AU - Tischer, Alexander

AU - Zimmermann, Michael T.

AU - Kemppainen, Jennifer L.

AU - Sastry, Sujatha

AU - Knight Johnson, Amy E.

AU - Cousin, Margot A.

AU - Boczek, Nicole J.

AU - Oliver, Gavin

AU - Misra, Vinod K.

AU - Gavrilova, Ralitza M

AU - Lomberk, Gwen

AU - Auton, Matthew T

AU - Urrutia, Raul

AU - Klee, Eric W

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