Describe the similarities and differences between the helixl

Describe the similarities and differences between the helix-loop-helix and the helix-turn-helix motifs of regulatory proteins and how they interact with the DNA double helix.

Solution

Helix turn helix is a major structural motif capable of binding DNA it is composed of two alpha helix joined by short strand of amino acid and is found in many protein that regulate gene expression while helix loop helix domain is characterized by two sets of amino acid sequence that fold into ampiphathic alpha helix separated by flexible linker or loop of variable amino acid sequence and length .The HLH domain is a dimerization domain that allow protein to form homo or heterodimer.

Helix turn helix motif first DNA binding motif discovered. The HTH motif relies on hydrophobic core through which two helices pack together The second helix interact with major groove of DNA.