Sry-directed sex reversal in transgenic mice is robust with respect to enhanced DNA bending: comparison of human and murine HMG boxes.
The testis-determining factor SRY contains an HMG box DNA-bending domain. Human and murine factors (hSRY and mSRY, respectively) exhibit marked sequence divergence and are reported to differ markedly in DNA bending properties. Surprisingly, the combined application of time-resolved fluorescence resonance energy transfer (tr-FRET) and permutation gel electrophoresis demonstrates that the hSRY-DNA complex is more sharply bent than the murine complex and not less bent as previously reported. tr-FRET-based analyses of the distribution of end-to-end distances in the bent DNA-protein complexes further suggest that a broader range of DNA bend angles is populated in the murine ensemble than in the human ensemble. The two domains and their respective DNA complexes nevertheless exhibit similar thermodynamic stabilities. (1)H NMR spectra indicate analogous intercalation of distinct "cantilever" side chains (isoleucine or methionine) with subtle differences in induced DNA structure. Interchange of cantilevers does not affect DNA bending. That transgenic expression of either human or murine Sry in XX mice can confer a male somatic phenotype suggests that SRY-directed transcriptional regulation is robust to enhanced DNA bending and to changes in the precision of DNA bending. We propose that male-specific gene regulation requires DNA bending above a critical threshold set by architectural requirements of enhanceosome assembly.
Phillips
Nelson B
NB
Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4935, USA.
Nikolskaya
Tatiana
T
Jancso-Radek
Agnes
A
Ittah
Varda
V
Jiang
Fashun
F
Singh
Rupinder
R
Haas
Elisha
E
Weiss
Michael A
MA
D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D012734:Disorders of Sex Development; D005786:Gene Expression Regulation; D006609:High Mobility Group Proteins / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins; D010641:Phenotype; D017386:Sequence Homology, Amino Acid; D051876:Sex-Determining Region Y Protein; D013050:Spectrometry, Fluorescence; D014157:Transcription Factors; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; D009687:Nuclear Proteins; C497745:SRY protein, human; D051876:Sex-Determining Region Y Protein; C497746:Sry protein, mouse; D014157:Transcription Factors; D004247:DNA