The DNA bend angle and binding affinity of an HMG box increased by the presence of short terminal arms.

AUTOR(ES)

Lnenicek-Allen, M

RESUMO

The HMG box of human LEF-1 (hLEF-1, formerly TCF1alpha) has been expressed in four forms: a parent box of 81 amino acids and constructs having either a 10 amino acid C-terminal extension, a 9 amino acid N-terminal extension, or both. These four species have been compared for DNA binding and bending ability using a 28 bp recognition sequence from the TCR alpha-chain enhancer. In the bending assay, whereas the parent box and that with the N-terminal extension bent the DNA by 57/58 degrees, the box extended at the C-terminus bent the DNA by 77/78 degrees, irrespective of the presence or absence of the N-terminal extension. A 6- fold increase in DNA affinity also resulted from addition of both terminal extensions. These observations redefine the functional boundaries of the HMG box. The structure of a mouse LEF-1/DNA complex recently published [Love et al. (1995) Nature 376, 791-795] implies that the higher DNA affinity and in particular the increased bend angle observed are consequences, at least in part, of the C-terminal extension spanning the major groove on the inside of the DNA bend.

Documentos Relacionados

• DNA looping by the HMG-box domains of HMG1 and modulation of DNA binding by the acidic C-terminal domain.
• Operator binding by lambda repressor heterodimers with one or two N-terminal arms.
• Partial monosomy of chromosome 10 short arms.
• DNA binding by single HMG box model proteins
• High affinity binding of proteins HMG1 and HMG2 to semicatenated DNA loops