3pvb

Publication Abstract from PubMed

PKA holoenzymes containing two catalytic (C) subunits and a regulatory (R) subunit dimer are activated cooperatively by cAMP. While cooperativity involves the two tandem cAMP binding domains in each R-subunit, additional cooperativity is associated with the tetramer. Of critical importance is the flexible linker in R that contains an inhibitor site (IS). While the IS becomes ordered in the R:C heterodimer, the overall conformation of the tetramer is mediated largely by the N-Linker that connects the D/D domain to the IS. To understand how the N-Linker contributes to assembly of tetrameric holoenzymes, we engineered a monomeric RIalpha that contains most of the N-Linker, RIalpha(73-244), and crystallized a holoenzyme complex. Part of the N-linker is now ordered by interactions with a symmetry-related dimer. This complex of two symmetry-related dimers forms a tetramer that reveals novel mechanisms for allosteric regulation and has many features associated with full-length holoenzyme. A model of the tetrameric holoenzyme, based on this structure, is consistent with previous small angle X-ray and neutron scattering data, and is validated with new SAXS data and with an RIalpha mutation localized to a novel interface unique to the tetramer.

Realizing the allosteric potential of the tetrameric protein kinase A RIalpha holoenzyme.,Boettcher AJ, Wu J, Kim C, Yang J, Bruystens J, Cheung N, Pennypacker JK, Blumenthal DA, Kornev AP, Taylor SS Structure. 2011 Feb 9;19(2):265-76. PMID:21300294^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.