Download MendeleyStructure of Yeast Regulatory Subunit: A Glimpse into the Evolution of PKA Signaling.
Rinaldi, J., Wu, J., Yang, J., Ralston, C.Y., Sankaran, B., Moreno, S., Taylor, S.S.(2010) Structure 18: 1471-1482
- PubMed: 21070946
- DOI: https://doi.org/10.1016/j.str.2010.08.013
- Primary Citation of Related Structures:
3OF1 - PubMed Abstract:
The major cAMP receptors in eukaryotes are the regulatory (R) subunits of PKA, an allosteric enzyme conserved in fungi through mammals. While mammals have four R-subunit genes, Saccharomyces cerevisiae has only one, Bcy1. To achieve a molecular understanding of PKA activation in yeast and to explore the evolution of cyclic-nucleotide binding (CNB) domains, we solved the structure of cAMP-bound Bcy1(168-416). Surprisingly, the relative orientation of the two CNB domains in Bcy1 is very different from mammalian R-subunits. This quaternary structure is defined primarily by a fungi-specific sequence in the hinge between the αB/αC helices of the CNB-A domain. The unique interface between the two CNB domains in Bcy1 defines the allosteric mechanism for cooperative activation of PKA by cAMP. Some interface motifs are isoform-specific while others, although conserved, play surprisingly different roles in each R-subunit. Phylogenetic analysis shows that structural differences in Bcy1 are shared by fungi of the subphylum Saccharomycotina.
Organizational Affiliation:
Department of Biological Chemistry, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, 1428 Buenos Aires, Argentina.
