Molecular Basis for Regulatory Subunit Diversity in cAMP-Dependent Protein Kinase

Abstract

Both the diversity and similarity of cAMP binding sites are demonstrated by this new type II regulatory subunit structure. The structure represents an intramolecular paradigm for the cooperative triad that links two cAMP binding sites through a domain interface to the catalytic subunit of cAMP-dependent protein kinase. The domain interface surface is created by the binding of only one cAMP molecule and is enabled by amino acid sequence variability within the peptide chain that tethers the two domains together.

Structural snapshot of cyclic nucleotide binding domains from cyclic nucleotide-sensitive ion channels

“…The β roll is surrounded by the N-terminal α-helix A, a short internal α-helix located between β-strands 6 and 7, designated as the phosphate-binding-cassette (PBC), and two α-helices B and C (αB and αC) located at the C-terminus. This structure, together with previously determined structures of PKA, CAP and Epac, confirmed the β roll topology to be conserved in all CNBDs (Weber and Steitz, 1987;Su et al, 1995;Diller et al, 2001;Rehmann et al, 2003).…”

“…The structure of the MloK1 CNBD shows the characteristic properties similar to the HCN2 CNBD structure (Figures 1 and 2), consisting of a β roll core topped by a bundle of four α-helices and a short PBC helix (Zagotta et al, 2003). Thus, the overall structure is highly conserved in all CNBDs (Weber and Steitz, 1987;Su et al, 1995;Diller et al, 2001;Rehmann et al, 2003).…”

Classification and Phylogenetic Analysis of the cAMP-Dependent Protein Kinase Regulatory Subunit Family

“…Priority was set to placing gaps within loops connecting secondary structure elements. The cAMP-binding regions were manually curated with the program GeneDoc (Nicholas et al 1997), taking into consideration the crystal structures of bovine RI␣ (Su et al 1995) and rat RII␤ (Diller et al 2001). The Gonnet weight matrix (Gonnet et al 1994) was used in the sequence alignments.…”

“…5). The alignment of the cAMP-binding domains was curated based on structural evidence from the crystal structures of bovine RI␣ (Su et al 1995) and rat RII␤ (Diller et al 2001). Most of the variability in the cAMP-binding domains corresponded to the loop between ␤-strand 4 and ␤-strand 5 of both domain A and domain B, and the C-terminal region.…”

“…The PBCs are defined as the segments of each cAMPbinding domain that contain most of the key residues for cAMP-mediated activation of PKA (Figs. 1B and C and 5) (Su et al 1995;Diller et al 2001).…”