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Title: Structure of a PKA RIα Recurrent Acrodysostosis Mutant Explains Defective cAMP-Dependent Activation

Most disease related mutations that impair PKA signaling are present within the regulatory PKA RI alpha-subunit (RIα). Although mutations in the PRKAR1A gene are linked to Carney complex disease (CNC) and more recently to acrodysostosis-1 (ACRDYS1), the two diseases show contrasting phenotypes. While CNC mutations cause increased PKA activity, ACRDYS1 mutations result in decreased PKA activity and cAMP resistant holoenzymes. Mapping the ACRDYS1 disease mutations reveals their localization to the second of two tandem cAMP binding domains (CNB-B) and here we characterize a recurrent deletion mutant where the last 14 residues are missing. The crystal structure of a monomeric form of this mutant (RIα92-365) bound to the C subunit reveals the dysfunctional regions of the RIα-subunit. Beyond the missing residues, the entire capping motif is disordered (residues 357-379) and explains the disrupted cAMP binding. Moreover, the effects of the mutation extend far beyond the CNB-B domain and include the active site and N-lobe of the C-subunit, which is in a partially open conformation with the C-tail disordered. A key residue that contributes to this crosstalk, D267, is altered in our structure and we confirmed its functional importance by mutagenesis. In particular, the D267 interaction with Arg241, a residue shown earliermore » to be important for allosteric regulation, is disrupted thereby strengthening the interaction of D267 with the C-subunit residue Arg194 at the R:C interface. Here, we see here how the switch between active (cAMP-bound) and inactive (holoenzyme) conformations is perturbed and how the dynamically controlled crosstalk between the helical domains of the two CNB-domains is necessary for functional regulation of PKA activity.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ; ORCiD logo [1] ;  [2] ;  [3] ;  [3] ;  [1]
  1. Univ. of California at San Diego, La Jolla, CA (United States)
  2. Univ. of Utah, Salt Lake City, UT (United States)
  3. Univ. of Innsbruck, Innsbruck (Austria)
Publication Date:
Grant/Contract Number:
FG02-05ER64026; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Journal of Molecular Biology
Additional Journal Information:
Journal Volume: 428; Journal Issue: PB; Journal ID: ISSN 0022-2836
Publisher:
Elsevier
Research Org:
Univ. of Utah, Salt Lake City, UT (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; PKA signaling; RIα subunit; disease mutations; crystal structure
OSTI Identifier:
1422048
Alternate Identifier(s):
OSTI ID: 1410896