Crystal structure of an intracellular protease from Pyrococcus horikoshii at 2-Å resolution

Crystal structure of an intracellular protease from Pyrococcus horikoshii at 2-Å resolution

^*Department of Chemistry, University of California, Berkeley, CA 94720; and ^‡Structural Biology Department, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720

Contributed by Sung-Hou Kim

Abstract

The intracellular protease from Pyrococcus horikoshii (PH1704) and PfpI from Pyrococcus furiosus are members of a class of intracellular proteases that have no sequence homology to any other known protease family. We report the crystal structure of PH1704 at 2.0-Å resolution. The protease is tentatively identified as a cysteine protease based on the presence of cysteine (residue 100) in a nucleophile elbow motif. In the crystal, PH1704 forms a hexameric ring structure, and the active sites are formed at the interfaces between three pairs of monomers.

Footnotes

↵ † Present address: Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75235.
↵ § To whom reprint requests should be addressed. E-mail address: shkim{at}cchem.berkeley.edu.
Data deposition: The atomic coordinates have been deposited in the Protein Data Bank, www.rcsb.org (PDB ID code 1G2I).
Article published online before print: Proc. Natl. Acad. Sci. USA, 10.1073/pnas.260503597.
Article and publication date are at www.pnas.org/cgi/doi/10.1073/pnas.260503597
Abbreviations:

PH1704,

Pyrococcus horikoshii 1704 gene product;

PfpI,

Pyrococcus furiosus intracellular protease;

NCS,

noncrystallographic symmetry;

rmsd,

rms deviation