Crystal of bacterial core RNA polymerase and methods of use thereof

A crystallized polypeptide comprising:

• (a) at least one of the amino acid sequences set forth in SEQ ID NO:
• 1 or SEQ ID NO:
• 2 or SEQ ID NO:
• 3;
• or (b) an amino acid sequence that is substantially similar to at least one of the amino acid sequences set forth in SEQ ID NO:
• 1 or SEQ ID NO:
• 2 or SEQ ID NO:
• 3;
• and has at least one biological activity of a core RNA polymerase from Thermus aquaticus wherein the polypeptide of (a), (b) or (c) is in crystal form and wherein said crystallized polypeptide diffracts x-rays to a resolution of about 3.5 Å or better for the determination of the three-dimensional atomic coordinates of said core RNA polymerase.