Structural insights into calmodulin/adenylyl cyclase 8 interaction.
Calmodulin (CaM) is a highly conserved intracellular Ca(2+)-binding protein that exerts important functions in many cellular processes. Prominent examples of CaM-regulated proteins are adenylyl cyclases (ACs), which synthesize cAMP as a central second messenger. The interaction of ACs with CaM represents the link between Ca(2+)-signaling and cAMP-signaling pathways. Thereby, different AC isoforms stimulated by CaM, comprise diverse mechanisms of regulation by the Ca(2+) sensor. To extend the structural information about the detailed mechanisms underlying the regulation of AC8 by CaM, we employed an integrated approach combining chemical cross-linking and mass spectrometry with two peptides representing the CaM-binding regions of AC8. These experiments reveal that the structures of CaM/AC8 peptide complexes are similar to that of the CaM/skeletal muscle myosin light chain kinase peptide complex where CaM is collapsed around the target peptide that binds to CaM in an antiparallel orientation. Cross-linking experiments were complemented by investigating the binding of AC8 peptides to CaM thermodynamically with isothermal titration calorimetry. There were no hints on a complex, in which both AC8 peptides bind simultaneously to CaM, refining our current understanding of the interaction between CaM and AC8.
Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin-Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120, Halle, Germany.
Sabine
S
Herbst
Nana
N
Masada
Sabrina
S
Pfennig
Christian H
CH
Ihling
Dermot M F
DM
Cooper
Andrea
A
Sinz
D000262:Adenylyl Cyclases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002417:Cattle; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013816:Thermodynamics
D002147:Calmodulin; D000262:Adenylyl Cyclases; C118292:adenylyl cyclase 8; D002118:Calcium