Conformational stability and DNA binding specificity of the cardiac T-box transcription factor Tbx20.
The transcription factor Tbx20 acts within a hierarchy of T-box factors in lineage specification and morphogenesis in the mammalian heart and is mutated in congenital heart disease. T-box family members share a approximately 20-kDa DNA-binding domain termed the T-box. The question of how highly homologous T-box proteins achieve differential transcriptional control in heart development, while apparently binding to the same DNA sequence, remains unresolved. Here we show that the optimal DNA recognition sequence for the T-box of Tbx20 corresponds to a T-half-site. Furthermore, we demonstrate using purified recombinant domains that distinct T-boxes show significant differences in the affinity and kinetics of binding and in conformational stability, with the T-box of Tbx20 displaying molten globule character. Our data highlight unique features of Tbx20 and suggest mechanistic ways in which cardiac T-box factors might interact synergistically and/or competitively within the cardiac regulatory network.
School of Molecular and Microbial Biosciences, University of Sydney, Sydney, NSW 2006, Australia.
Ingrid
I
Macindoe
Laura
L
Glockner
Paul
P
Vukasin
Fiona A
FA
Stennard
Mauro W
MW
Costa
Richard P
RP
Harvey
Joel P
JP
Mackay
Margaret
M
Sunde
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016384:Consensus Sequence; D004247:DNA / Q000737:chemistry*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D020825:T-Box Domain Proteins / Q000737:chemistry*
D020825:T-Box Domain Proteins; C420984:TBX20 protein, human; C486013:Tbx20 protein, mouse; D004247:DNA