Biochemical and phenotypic characteristics of the children affected by GCK MODY

a<p>BMI<i>z</i> scores: (calculated in children aged 2–18 years), see Materials and methods</p>b<p>FPG: Fasting plasma glucose; (impaired fasting glucose [IFG] = 5.6–6.9 mmol/L; diabetes mellitus [DM] = ≥7.0 mmol/L)</p>c<p>OGTT: Oral glucose tolerance test (normal glucose tolerance [NGT] <7.8 mmol/L; impaired glucose tolerance [IGT] = 7.8–11.0 mmol/L; DM = ≥11.1 mmol/L)</p>d<p>FPIR: First phase insulin response (reference value: ≥60.0 µU/ml)</p>e<p>HbA1c: glycosylated haemoglobin (reference value: 4.3–5.9%)</p>f<p>Not available because patient M002 was <2 years old</p>g<p>Not fasting nursling</p>n.a.<p>Not available</p

GCK mutations in children from south Italy affected by GCK MODY

a<p>GenBank: accession n° (AH005826)</p>b<p>The reference cDNA sequence was obtained from GenBank (NM_000162) and +1corresponds to the A of the ATG translation initiation codon</p>c<p>Swissprot accession n° P35557</p>d, e, f<p>Sibling pairs</p

Distribution of the GCK mutations.

<p>The structure of GCK in the closed form (PDB code: 1v4s) is shown as cyan and red ribbons that represent the small and large domain, respectively. Orange ribbons show the α13 helix. Yellow spheres are the mutation sites. Red and blue circles indicate clusters of mutations in the large and small domain, respectively.</p

Structural features of mutations p.Phe123Leu and p.Asp168Ala GCK.

<p>The structure of GCK in the closed form (PDB code: 1v4s) is represented by cyan ribbons. A) Mutation p.Phe123Leu. Phe123 is structured inside the hydrophobic core of the small domain. Yellow sticks represent hydrophobic residues that constitute the core. Phe123 and Leu123 are represented by red sticks (left and right panel, respectively). B) The sticks represent residue Thr168 and glucose. The right panels show a close-up view of the glucose-binding cleft for the wild-type (top) and for the Ala168 mutant (bottom).</p

Structural features of mutations p.His137Asp, p.Arg392Ser and p.Gly162Asp GCK.

<p>The structure of GCK in the closed form (PDB code:1v4s) is shown as cyan ribbons. A) p.His137Asp. Loop 141–144, which is involved in GKRP binding, is in red. His137 is at the end of the α3 helix. His137 is a capping residue of the helix, which is terminated by the interaction between side chain of His137 and Phe133. Asp137 (right) is not able to replace His137 interactions but adds a new interaction with Lys104. B) p.Gly162Asp. Yellow sticks represent hydrophobic residues that constitute the core. The location of Gly162 is marked in red (left of the panel). Asp162 is on the right of the panel. C) p.Arg392Ser. Residues Asp42, Glu236, Asn240 and Arg392 are represented by yellow sticks. H-bonds are shown in green. The wild-type enzyme and the p.Arg392Ser mutant are on the left and right of the panel, respectively.</p

GCK mutations detected in MODY2 children from South Italy.

a<p>GenBank: accession number (AH005826). ^bThe reference cDNA sequence was obtained from GenBank (NM_000162) and +1 corresponds to the A of the ATG translation initiation codon. ^cPolyphen prediction: probably damaging (1), benign (2), possibly damaging (3). SIFT score: <0.05 deleterious variant, ≥0.05 tolerated variant. ^dSwissprot accession number: P35557. ^eSibling pairs (MD19/20: two sisters; MD69/70: brother/sister).</p

Kinetic constants of human recombinant wild type-GCK and mutant β-cell GST-GCK fusion proteins.

<p>Data represent means ± SEM of 3 separate enzyme expressions each tested in duplicate. Note that the Hill coefficient (nH) and the relative activity index (I_a) are unit less. Kcat: GCK catalytic constant; S_0.5: affinity constant for glucose; nH: Hill coefficient; Km for ATP: affinity constant for ATP; I_a: GCK activity index. (*)<i>p</i><0.05, <i>t</i> test; (**)<i>p</i><0.005, <i>t</i> test.</p

Effect of temperature on the stability of GST-GCK mutants

<p>. Stock enzyme solutions were diluted to 250 µg/ml in storage buffer containing 30% glycerol, 50 mM glucose, 10 mM glutathione, 5 mM DTT, 200 mM KCl and 50 mMTris/HCl, pH 8.0. Panel A: The enzyme solutions were incubated for 30 min at temperatures ranging from 30 to 55°C and then assayed at 30°C as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038906#s4" target="_blank">Methods</a> section. Panel B: The enzyme solutions were incubated for periods of time from 5 to 60 min at 50°C. Results are means and SEM of three independent enzyme preparations for each mutant except for GST-GCK (Phe150Tyr) which corresponds to two independent enzyme preparations. (*) <i>p</i>≤0.03, (†) <i>p</i><0.008.</p

Physical map of the 15q11.2-q14 region.

<p>The six segmental duplication sites responsible for specific recurrent rearrangements in this region, known as BP1-6, are represented by black boxes. All genes in the region are shown. The position of the chromosome 15 breakpoints of the five translocation cases we have examined are represented by thin arrows. The positions of the eight translocation cases (MR1-8) described by Mignon-Ravix <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039180#pone.0039180-MignonRavix1" target="_blank">[10]</a> are indicated by thick arrows.</p

Phenotype, karyotype and molecular characterization of the five cases with unbalanced translocations.

*<p>The minor cell line has been confirmed, by classical cytogenetics, in fibroblasts, with a similar mosaicism percentage (45, XX, der(15;18)(q13;q23)[83]-15/45, X, der (X;15)(q28;q13),-15<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039180#pone.0039180-Carrozzo1" target="_blank">[3]</a>*).</p