Final Answer:
The Helix-turn-Helix (HTH) motif is a common DNA-binding motif found in many proteins involved in gene regulation. It consists of two alpha helices connected by a short turn. In the context of DNA interaction, the HTH motif recognizes specific DNA sequences and binds to them through the second helix, facilitating gene expression regulation.
Step-by-step explanation:
The Helix-turn-Helix (HTH) motif is a structural motif found in proteins that interact with DNA. It typically consists of two alpha helices connected by a short loop or turn. The first helix is responsible for the structural stability of the motif, while the second helix is involved in DNA recognition and binding. The specific interaction with DNA is mediated by amino acid residues located on the second helix, forming hydrogen bonds and other non-covalent interactions with the DNA bases.
In the HTH motif, the recognition helix fits into the major groove of the DNA, allowing for specific interactions with the DNA sequence. The residues on the recognition helix often form a set of amino acids, known as the "recognition helix residues," that make sequence-specific contacts with the DNA bases. This specificity enables the HTH motif to selectively bind to particular DNA sequences, playing a crucial role in gene regulation.
The HTH motif is commonly found in transcription factors, which are proteins that regulate the transcription of genes. By binding to specific DNA sequences, the HTH motif facilitates the recruitment of other proteins and regulatory elements, ultimately influencing gene expression. Understanding the structure and function of the HTH motif is fundamental to deciphering the molecular mechanisms underlying gene regulation in various biological processes.
Fulll Question:
Explain the structure of Helix-turn-Helix (HTH) motifs and how they interact with DNA.