CPK Color Scheme

On this page, you can see the helicase of the Hepatitis C Virus.

Spin this helicase. Notice the two chains of the HCV NS3h protein. Since the two chains are identical, some of these buttons will hide chain B for clarity.

Secondary structure of the protein is highlighted. Alpha helices are shown in pink, beta pleated sheets in yellow, and nucleic acids in purple.

DNA is spacefilled by this button so that the interaction between the helicase and DNA can be seen more clearly.

Domain 1 is colored yellow. Domain 1 is highly conserved among helicases and encodes the ATP binding site for this protein.

Domain 2 is colored blue. This domain is also highly conserved among helicases. It appears that domain 2 is linked to domain 1 and 3 by flexible linkers allowing this domain to rotate.

Notice Domain 3 for this protein in green. This domain is not found in any other species of helicase but nevertheless is essential to the function of this protein.

Amino acid at position 450 is colored white. Some strains of HCV have a Thr at this position while others contain an Ile. The strain with Ile unwinds DNA more quickly. It is hypothesized that this mutation is an adaptive mutation allowing HCV to perform more efficiently in the chimpanzee (1).

The Arg amino acid at position 393 is colored orange. This residue is hypothesized to be in contact with the nucleic acid that the helicase acts on. When the amino acid at this position is changed to an Ala, the helicase no longer unwinds nucleic acid strands (1).

Amino acids 438-444 are colored pink. These amino acids lie in a highly conserved region of a loop that extends from domain 2. Amino acid 438 and 444 are a pair of Phe that are important to the release of nucleic acids after ATP has bound to the enzyme (1).

1. Tan, S, editor. Hepatitis C Virus: Genomes and Molecular Biology. Norfolk, UK: Horizon Bioscience; 2006. 207-244 p.

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