TATA binding protein (TBP)/DNA complex
Homo sapiens (human)
DNA contains the genetic information for making proteins. The process is however very complex, involving many different kinds of molecules, that proceeds in two basic steps: transcription and translation, first transcribing the DNA into a particular type of RNA, the messenger RNA or mRNA. The information contained in the mRNA is then translated in the next step into proteins. Each three base pairs on the DNA correspond to one amino acid residue on a protein. As the DNA is designed, it can be thought of as a cylinder. The outside wall of this cylinder is the sugar-phosphate backbone to which the bases are attached. The actual information, the bases, is inside the cylinder and not directly accessible. The DNA information containing the code for a protein contains start and stop signals, telling the machinery of protein production where the code for a protein begins and where it ends. The proteins that perform the conversion from DNA to RNA, so-called RNA polymerases, work together with other proteins called transcription initiation factors. Here we see such a transcription factor in action.
This protein recognizes a specific DNA sequence, thymine-adenine-thymine-adenine (TATA). This is called the TATA-box. Because of base pairing rules in DNA the opposite DNA strand has the sequence TATA as well. The protein that binds to this particular DNA sequence is the TATA-box binding protein. Its two domains are similar to each other. The shape of the protein enables it to attach to and wrap around part of the DNA. When the protein binds, the interaction between the protein and the DNA results in a severe deformation of the DNA shape. This process helps other proteins to unwind the DNA, so that information in the form of specific bases becomes accessible for further transcription.
Protein Data Bank (PDB)
author: Arno Paehler