'Two-component' phosphorelay signal transduction systems constitute a potential target for antibacterial and antifungal agents, since they are found exclusively in prokaryotes and lower eukaryotes (yeast, fungi, slime mold, and plants) but not in mammalian organisms. Saccharomyces cerevisiae Ypd1y, a key intermediate in the osmosensing multistep phosphorelay signal transduction, catalyzes the phosphoryl group transfer between response regulators. Its 1.8 Å structure, representing the first example of a eukaryotic phosphorelay protein, contains a four-helix bundle as in the HPt domain of Escherichia coli ArcB sensor kinase. However, Ypd1p has a 44-residue insertion between the last two helices of the helix bundle. The side-chain of His64, the site of phosphorylation, protrudes into the solvent. The structural resemblance between Ypd1p and ArcB HPt domain suggests that both prokaryotes and lower eukaryotes utilize the same basic protein fold for phosphorelay signal transduction. This study sheds light on the best characterized eukaryotic phosphorelay system.
Bibliographical noteFunding Information:
We thank the Inter-University Center for Natural Science Research Facilities for providing the X-ray equipment. We thank Professor N. Sakabe, Dr N. Watanabe, Dr M. Suzuki, and Dr N. Igarashi for assistance during data collection at BL-6A and BL-6B (TARA beamline) of Photon Factory, Japan. We thank Dr F. W. Dahlquist and Dr J.-P. Samama for kindly providing us the coordinates of the P1 domain of CheA and the complex between the P2 domain of CheA and CheY. H.K.S. is supported by the Postdoctoral Fellowship from Korea Ministry of Education. This work was supported by a grant from Korea Science and Engineering Foundation through the Center for Molecular Catalysis at Seoul National University.
- Crystal structure
- Phosphorelay phosphotransferase
- Saccharomyces cerevisiae
- Signal transduction
ASJC Scopus subject areas
- Structural Biology
- Molecular Biology