What does a helix-turn-helix DNA binding protein contain?

What does a helix-turn-helix DNA binding protein contain?

In proteins, the helix-turn-helix (HTH) is a major structural motif capable of binding DNA. Each monomer incorporates two α helices, joined by a short strand of amino acids, that bind to the major groove of DNA. The HTH motif occurs in many proteins that regulate gene expression.

What is the structure of a helix loop helix protein?

Structure. The motif is characterized by two α-helices connected by a loop. In general, transcription factors including this domain are dimeric, each with one helix containing basic amino acid residues that facilitate DNA binding.

What is the function of helix loop helix?

The basic helix-loop-helix (bHLH) proteins form a large superfamily of transcriptional regulators that are found in organisms from yeast to humans and function in critical developmental processes, including sex determination and the development of the nervous system and muscles.

Is an example of a helix-turn-helix motif?

The helix-turn-helix motif is a common tertiary structure motif found in DNA-binding proteins. Examples in Proteopedia include the Lac repressor and Biotin Protein Ligase. For more information, please see helix-turn-helix in Wikipedia.

Is a leucine zipper a helix-turn-helix?

(iii) Leucine-zipper motif. The leucine zipper is an amphipathic a helix containing heptad repeats of Leu residues on one face of the helix and serves as a dimerization module.

Why do proteins bind to the major groove?

As you noted, the major groove is wider than the minor groove. These grooves allow proteins to bind to and recognize DNA sequences from the outside of the helix. The grooves expose the edges of each base pair located inside the helix, which allows proteins to chemically recognize specific DNA sequences.

What is a zinc finger domain?

Domain. Zinc finger (Znf) domains are relatively small protein motifs that contain multiple finger-like protrusions that make tandem contacts with their target molecule. Some of these domains bind zinc, but many do not, instead binding other metals such as iron, or no metal at all.

What is a bHLH domain?

The bHLH domain defines a large and diverse family of transcriptional regulators that function prominently in the development of the nervous system as well as in other organ systems, including muscle, pancreas, and blood (Massari and Murre, 2000).

Are zinc fingers transcription factors?

Zinc finger proteins are the largest transcription factor family in human genome. The diverse combinations and functions of zinc finger motifs make zinc finger proteins versatile in biological processes, including development, differentiation, metabolism and autophagy.

Is a leucine zipper a helix turn helix?

What is a helical shape?

A helix is a twisted, spiral shape, like a corkscrew. In math, a helix is defined as “a curve in three-dimensional space.” If you have ever seen a spiral staircase, you can envision the shape of a helix. In both Latin and Greek, helix means “spiral” or “spiral-shaped thing.”

How is the helix turn helix motif used in proteins?

In proteins, the helix-turn-helix (HTH) is a major structural motif capable of binding DNA. Each monomer incorporates two α helices, joined by a short strand of amino acids, that bind to the major groove of DNA. The HTH motif occurs in many proteins that regulate gene expression. It should not be confused with the helix–loop–helix motif.

Where are the helices located in a helix turn helix?

The helix-turn-helix motif is a DNA-binding motif. The recognition and binding to DNA by helix-turn-helix proteins is done by the two α helices, one occupying the N-terminal end of the motif, the other at the C-terminus.

Can a π helix be found in a protein?

A long left-handed π-helix is unlikely to be observed in proteins because, among the naturally occurring amino acids, only glycine is likely to adopt positive φ dihedral angles such as 55°. A short, 7 residue π-helix (orange) is embedded within a longer, α-helix (green).

What makes a helix a DNA binding helix?

One helix usually serves as a primary DNA-binding ‘recognition’ helix that fits along its length into the major groove of the common B-form of DNA (Figure 7.2A ). This interaction usually provides most of the binding specificity, but usually has an insufficient number of molecular contacts to provide stable association.