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Resolving the structure of Bcy1, the Regulatory Subunit of Yeast Protein Kinase A
Author(s) -
Núñez Lucas Matías Fernández,
Bardeci Nicolás González,
Rossi Silvia,
Blumenthal Donald,
Moreno Silvia
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.768.3
Subject(s) - protein subunit , small angle x ray scattering , saccharomyces cerevisiae , chemistry , crystallography , protein kinase a , homology modeling , docking (animal) , stereochemistry , kinase , yeast , biochemistry , enzyme , scattering , physics , medicine , nursing , optics , gene
The major receptor for cAMP signaling in eukaryotes is the regulatory subunit (R) of protein kinase A. Saccharomyces cerevisiae has one R (Bcy1). R subunits are homodimers comprising an N‐terminal dimerization/docking domain (D/D), an inhibitory hinge region, and two tandem cAMP binding domains (CNB) at the C‐terminus. The crystal structure of Bcy1(168–416) has been solved. The relative orientation of the two CNB domains is different from RIα and RIIβ. We have analyzed the solution structure of Bcy1 whole molecule and of a monomer (Δ140)Bcy1 by small‐angle x‐ray scattering (SAXS). The Rg (gyration radius) and dmax (derived from the P(r) function) of the molecules were determined. Both structures were modeled ab initio using the DAMMIN program. The resulting structure of (Δ 140)Bcy1 compares very favorably with the crystal structure, thus confirming the particular relative orientation of the CNB domains The structure of the whole homodimer is predicted to be different from RI and RII. The N terminus of Bcy1 was modeled by homology using Swiss Model and further minimization with the GROMACS package. It shares with its counterparts the residues important for dimerization; however the exposed surface, that should interact with anchoring proteins (not described yet in yeast), has characteristics of its own.