The structure of bacteriophage T7 lysozyme, a zinc amidase and an inhibitor of T7 RNA polymerase
- W.M. Keck Structural Biology Lab., Cold Spring Harbor, NY (United States)
- Brookhaven National Lab., Upton, NY (United States)
The lysozyme of bacteriophage T7 is a bifunctional protein that cuts amide bonds in the bacterial cell wall and binds to and inhibits transcription by T7 RNA polymerase. The structure of a mutant T7 lysozyme has been determined by x-ray crystallography and refined at 2.2-{angstrom} resolution. The protein folds into an {alpha}/{beta}-sheet structure that has a prominent cleft. A zinc atom is located in the cleft, bound directly to three amino acids and, through a water molecule, to a fourth. Zinc is required for amidase activity but not for inhibition of T7 RNA polymerase. Alignment of the zinc ligands of T7 lysozyme with those of carboxypeptidase A and thermolysin suggests structural similarity among the catalytic sites for the amidase and these zinc proteases. Mutational analysis identified presumed catalytic residues for amidase activity within the cleft and a surface that appears to be the site of binding to T7 RNA polymerase. Binding of T7 RNA polymerase inhibits amidase activity.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 86511
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Vol. 91, Issue 9; Other Information: PBD: 26 Apr 1994
- Country of Publication:
- United States
- Language:
- English
Similar Records
Cloning and expression of autogenes encoding RNA polymerases of T7-like bacteriophages
Cloning and expression of autogenes encoding RNA polymerases of T7-like bacteriophages