[Campbell Biology P.383] This image shows DNA gray interacting with a computer-generated mod... | Practice Question

This image shows DNA gray interacting with a computer-generated model of a TAL protein multicolored , one of a family of proteins found only in a species of the bacterium Xanthomonas. The bacterium uses proteins like this one to find specific gene sequences in cells of the organisms it infects, such as tomatoes, rice, and citrus fruits. Which of the following is most strongly suggested by the image and text regarding the TAL protein's function?

  • A: The TAL protein forms a channel through which DNA can pass, facilitating gene transfer.
  • B: The TAL protein’s multiple colored domains indicate its ability to cleave DNA at multiple sites.
  • C: The TAL protein's elongated, groove-fitting structure allows it to specifically recognize and bind to the major groove of DNA.
  • D: The TAL protein acts as a chaperone, guiding DNA folding into a compact chromosome structure.

Explanation

The image depicts the TAL protein wrapping around the DNA helix, specifically appearing to fit into the major groove. The text states that these proteins 'find specific gene sequences,' which implies sequence-specific DNA binding. Many DNA-binding proteins, especially those recognizing specific sequences, interact with the DNA bases exposed in the major groove due to its wider and deeper nature, allowing for precise recognition. The elongated and somewhat helical structure of the TAL protein in the image is consistent with this type of interaction, allowing it to 'read' the DNA sequence.