A Novel Missense Mutation in TNNI3K Causes Recessively Inherited Cardiac Conduction Disease in a Consanguineous Pakistani Family

Figures

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  Figure 1. Pedigree, sequencing chromatogram, and location of the TNNI3K variant in the family with cardiac conduction disease (CCD). (a) Family pedigree. The open symbols represent unaffected individuals and the filled symbols represent affected individuals; symbols with a diagonal line represent deceased individuals; and the arrowhead designates the proband. An asterisk indicates family members from whom DNA was available. The genotypes of the TNNI3K mutation are indicated below each examined member: CC (homozygote); TC (heterozygote); number inside the circle denote the number of individuals. (b) Sequencing chromatograms. Vertical arrows indicate the mutation site. (c) Schematic of the human TNNI3K gene. The positions of coding exons (black) and UTRs (white) are indicated. Black arrows indicate previously reported pathogenic variants and the red arrow shows the novel variant c.1531T>C in exon 16. (d) Initial 3D structure of TNNI3K-WT (PDB-ID: 4YFI [29]) shown as a ribbon. Monomer I is shown in gray and monomer II in green. The Cα atoms of Ser511 (red), Gly526 (blue), and Thr539 (blue) of monomer I are shown in spheres relative to the ATP-binding pocket (orange surface) of monomer I.…

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  Figure 2. Root mean square fluctuation, hydrogen bond analysis, and electrostatic surface potential map. (a) Comparison of root mean square fluctuation values of TNNI3K-WT (green) and TNNI3K-S511P (blue) during three independent 1 µs MD simulations with error bars. Alignments and measurements were performed for the Cα carbon atoms. (b) Hydrogen bond analysis. Length of the hydrogen bonds between Cys507 and Ser511 in TNNI3K-WT as a mean value of three independent MD simulations (1 µs). (c,d) A comparison of the electrostatic surface potential of TNNI3K-WT (c) and TNNI3K-S511P (d), demonstrating that p.Ser511Pro leads to a more hydrophobic protein surface (“red white blue” color ramp with a minimum of −0.3 and a maximum of 0.3).

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  Figure 3. Average intra/inter residue-residue contact maps and MM/GBSA analysis. (a) Contact map of the residues of helix 2 in monomer I and the residues of the corresponding monomer, and (b) residues of helix 2 in monomer II and the residues of the corresponding monomer. Each point represents the mean of the average residue-residue contact difference between TNNI3K-WT and TNNI3K-S511P over the last 200 ns from the three independent MD simulations (spectrum range from green to white to blue, from 100% to −100% contact; green means more contacts in TNNI3K-WT and blue means more contacts in TNNI3K-S511P). (c) Contact map between residue-residue pairs in the dimer interface for TNNI3K-WT vs. TNNI3K-S511P. The contact spectrum ranging from green to white to blue, representing 100% to −100% contact, where green indicates more contacts in TNNI3K-WT and blue indicates more contacts in TNNI3K-S511P. Each point represents the mean difference in the residue-residue contact over the last 200 ns from the three independent MD simulations. (d) MM/GBSA analysis applied for dimerization of TNNI3K. Every 10th snapshot of the last 200 ns of the MD simulation was used. Each violin plot represents the mean…