Structural highlights
Function
[KAPR_YEAST] Regulatory subunit of the cyclic AMP-dependent protein kinase (PKA), an effector of the Ras/cAMP pathway. Inhibits PKA activity in the absence of cAMP. cAMP activates PKA and promotes growth and proliferation in response to good nutrient conditions. Together with ZDS1, provides a negative feedback control on the cell wall integrity-signaling pathway by acting as a negative regulator of MAP kinase SLT2/MPK1.[1] [2] [3] [4]
Publication Abstract from PubMed
Protein kinase A (PKA) is a widespread enzyme that plays a key role in many signaling pathways from lower eukaryotes to metazoans. In mammals, the regulatory (R) subunits sequester and target the catalytic (C) subunits to proper subcellular locations. This targeting is accomplished by the dimerization and docking (D/D) domain of the R subunits. The activation of the holoenzyme depends on the binding of the second messenger cAMP. The only available structures of the D/D domain proceed from mammalian sources. Unlike dimeric mammalian counterparts, the R subunit from Saccharomyces cerevisiae (Bcy1) forms tetramers in solution. Here we describe the first high-resolution structure of a non-mammalian D/D domain. The tetramer in the crystals of the Bcy1 D/D domain is a dimer of dimers that retain the classical D/D domain fold. By using phylogenetic and structural analyses combined with site-directed mutagenesis, we found that fungal R subunits present an insertion of a single amino acid at the D/D domain that shifts the position of a downstream, conserved arginine. This residue participates in intra-dimer interactions in mammalian D/D domains, while due to this insertion it is involved in inter-dimer contacts in Bcy1, which are crucial for the stability of the tetramer. This surprising finding challenges well-established concepts regarding the oligomeric state within the PKAR protein family and provides important insights into the yet unexplored structural diversity of the D/D domains and the molecular determinants of R subunit oligomerization.
The crystal structure of yeast regulatory subunit reveals key evolutionary insights into Protein Kinase A oligomerization.,Bardeci NG, Tofolon E, Trajtenberg F, Caramelo J, Larrieux N, Rossi S, Buschiazzo A, Moreno S J Struct Biol. 2021 Apr 2:107732. doi: 10.1016/j.jsb.2021.107732. PMID:33819633[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Toda T, Cameron S, Sass P, Zoller M, Scott JD, McMullen B, Hurwitz M, Krebs EG, Wigler M. Cloning and characterization of BCY1, a locus encoding a regulatory subunit of the cyclic AMP-dependent protein kinase in Saccharomyces cerevisiae. Mol Cell Biol. 1987 Apr;7(4):1371-7. PMID:3037314
- ↑ Cannon JF, Tatchell K. Characterization of Saccharomyces cerevisiae genes encoding subunits of cyclic AMP-dependent protein kinase. Mol Cell Biol. 1987 Aug;7(8):2653-63. PMID:2823100
- ↑ Hixson CS, Krebs EG. Characterization of a cyclic AMP-binding protein from bakers' yeast. Identification as a regulatory subunit of cyclic AMP-dependent protein kinase. J Biol Chem. 1980 Mar 10;255(5):2137-45. PMID:6243658
- ↑ Griffioen G, Swinnen S, Thevelein JM. Feedback inhibition on cell wall integrity signaling by Zds1 involves Gsk3 phosphorylation of a cAMP-dependent protein kinase regulatory subunit. J Biol Chem. 2003 Jun 27;278(26):23460-71. Epub 2003 Apr 18. PMID:12704202 doi:10.1074/jbc.M210691200
- ↑ Bardeci NG, Tofolon E, Trajtenberg F, Caramelo J, Larrieux N, Rossi S, Buschiazzo A, Moreno S. The crystal structure of yeast regulatory subunit reveals key evolutionary insights into Protein Kinase A oligomerization. J Struct Biol. 2021 Apr 2:107732. doi: 10.1016/j.jsb.2021.107732. PMID:33819633 doi:http://dx.doi.org/10.1016/j.jsb.2021.107732
