1H, 13C and 15N chemical shift assignments for the human Pitx2 homeodomain and a R24H homeodomain mutant

Abstract

The homeodomain is one of the most important eukaryotic DNA-binding motifs and has been identified in over one thousand proteins. Homeodomain proteins play critical roles in diverse biological processes, including cell differentiation and cell pattern formation. The human Pitx2 homeodomain binds several different DNA sequences and is a pivotal component of both the TGF-β and Wnt/ β-catenin signaling pathways. As the recognition of specific DNA sequences represents an essential biochemical function of all DNA-binding proteins, we have chosen the Pitx2 homeodomain model to investigate the mechanisms that convey biological specificity in these protein-DNA interactions. Here, we report complete chemical shift assignments of the human Pitx2 homeodomain and the R24H mutation that induces ring dermoid of the cornea syndrome.

Structural and Biophysical Insights into the Ligand-Free Pitx2 Homeodomain and a Ring Dermoid of the Cornea Inducing Homeodomain Mutant

“…94,95 In addition to the characterized picosecond to nanosecond motion, we have evidence that the N-terminal arm undergoes more complex motion on the microsecond to millisecond time scale. A comparison of the intensities of the amide backbone resonances 96 of the N-terminal arm with the resonances of the artificial C-terminal tail (Figure 2 of the Supporting Information) indicates strong peaks with narrow line widths for the C-terminal tail residues, but a very heterogeneous distribution for the N-terminal arm. Such resonance broadening, especially for residues 1 and 7, is the result of slower motions and warrants further examination to improve understanding of the dynamic nature of the N-terminal arm and its role in DNA and protein recognition and binding.…”

“…A disordered state, such as that described above for the N-terminal arm of the homeodomain, or motions on the slower microsecond to millisecond time scale often correlate to regions involved in protein function, including protein–protein and protein–DNA interactions. , In addition to the characterized picosecond to nanosecond motion, we have evidence that the N-terminal arm undergoes more complex motion on the microsecond to millisecond time scale. A comparison of the intensities of the amide backbone resonances of the N-terminal arm with the resonances of the artificial C-terminal tail (Figure 2 of the Supporting Information) indicates strong peaks with narrow line widths for the C-terminal tail residues, but a very heterogeneous distribution for the N-terminal arm. Such resonance broadening, especially for residues 1 and 7, is the result of slower motions and warrants further examination to improve our understanding of the dynamic nature of the N-terminal arm and its role in DNA and protein recognition and binding.…”

PITX2 deficiency and associated human disease: insights from the zebrafish model

“…Mice with deficiency of Dkk2 (an extracellular antagonist of canonical Wnt-β-catenin signaling and a previously identified downstream target of Pitx2) show corneal abnormalities, including a complete fate shift from corneal epithelium to stratified epidermis in some animals; the shift is attributed to aberrant regulation of localized Wnt signaling throughout the ocular mesenchyme and limbus ( 21 , 59 ). In humans, one report connected a missense mutation in PITX2 , p.(Arg62His), with ring dermoid of the cornea [MIM180550] in a large Chinese pedigree ( 12 , 60 , 61 ). Genetic studies in other human pedigrees affected with corneal dermoid and related phenotypes ( 62 ) may provide additional information about possible other PITX2 mutations in these conditions.…”