Mechanism of intracellular cAMP sensor Epac2 activation

cAMP-induced conformational changes identified by amide hydrogen/Deuterium Exchange Mass Spectrometry (DXMS)

Sheng Li, Tamara Tsalkova, Mark White, Fang C. Mei, Tong Liu, Daphne Wang, Virgil L. Woods, Xiaodong Cheng

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

Epac2, a guanine nucleotide exchange factor, regulates a wide variety of intracellular processes in response to second messenger cAMP. In this study, we have used peptide amide hydrogen/ deuterium exchange mass spectrometry to probe the solution structural and conformational dynamics of full-length Epac2 in the presence and absence of cAMP. The results support a mechanism in which cAMP-induced Epac2 activation is mediated by a major hinge motion centered on the C terminus of the second cAMP binding domain. This conformational change realigns the regulatory components of Epac2 away from the catalytic core, making the later available for effector binding. Furthermore, the interface between the first and second cAMP binding domains is highly dynamic, providing an explanation of how cAMP gains access to the ligand binding sites that, in the crystal structure, are seen to be mutually occluded by the other cAMP binding domain. Moreover, cAMP also induces conformational changes at the ionic latch/hairpin structure, which is directly involved in RAP1 binding. These results suggest that in addition to relieving the steric hindrance imposed upon the catalytic lobe by the regulatory lobe, cAMP may also be an allosteric modulator directly affecting the interaction between Epac2 and RAP1. Finally, cAMP binding also induces significant conformational changes in the dishevelled/Egl/pleckstrin (DEP) domain, a conserved structural motif that, although missing from the active Epac2 crystal structure, is important for Epac subcellular targeting and in vivo functions.

Original languageEnglish (US)
Pages (from-to)17889-17897
Number of pages9
JournalJournal of Biological Chemistry
Volume286
Issue number20
DOIs
StatePublished - May 20 2011

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Guanine Nucleotide Exchange Factors
Deuterium
Second Messenger Systems
Amides
Mass spectrometry
Hydrogen
Mass Spectrometry
Catalytic Domain
Crystal structure
Chemical activation
Binding Sites
Ligands
Peptides
Sensors
Hinges
Modulators
Ion exchange
platelet protein P47

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

Mechanism of intracellular cAMP sensor Epac2 activation : cAMP-induced conformational changes identified by amide hydrogen/Deuterium Exchange Mass Spectrometry (DXMS). / Li, Sheng; Tsalkova, Tamara; White, Mark; Mei, Fang C.; Liu, Tong; Wang, Daphne; Woods, Virgil L.; Cheng, Xiaodong.

In: Journal of Biological Chemistry, Vol. 286, No. 20, 20.05.2011, p. 17889-17897.

Research output: Contribution to journalArticle

Li, Sheng ; Tsalkova, Tamara ; White, Mark ; Mei, Fang C. ; Liu, Tong ; Wang, Daphne ; Woods, Virgil L. ; Cheng, Xiaodong. / Mechanism of intracellular cAMP sensor Epac2 activation : cAMP-induced conformational changes identified by amide hydrogen/Deuterium Exchange Mass Spectrometry (DXMS). In: Journal of Biological Chemistry. 2011 ; Vol. 286, No. 20. pp. 17889-17897.
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