1WC1

Soluble adenylyl cyclase CyaC from S. platensis in complex with Rp- ATPalphaS

Summary for 1WC1

• Entry DOI: 10.2210/pdb1wc1/pdb
• Related: 1WC0 1WC3 1WC4 1WC5 1WC6
• Descriptor: ADENYLATE CYCLASE, ADENOSINE-5'-RP-ALPHA-THIO-TRIPHOSPHATE, MAGNESIUM ION, ... (4 entities in total)
• Functional Keywords: cyclase, soluble adenylyl cyclase, camp signaling, lyase
• Biological source: SPIRULINA PLATENSIS
• Total number of polymer chains: 3
• Total formula weight: 76468.01

Authors

Steegborn, C.,Litvin, T.N.,Levin, L.R.,Buck, J.,Wu, H. (deposition date: 2004-11-06, release date: 2004-12-20, Last modification date: 2024-05-08)

Primary citation

Steegborn, C.,Litvin, T.N.,Levin, L.R.,Buck, J.,Wu, H.
Bicarbonate Activation of Adenylyl Cyclase Via Promotion of Catalytic Active Site Closure and Metal Recruitment
Nat.Struct.Mol.Biol., 12:32-, 2005

PubMed Abstract: In an evolutionarily conserved signaling pathway, 'soluble' adenylyl cyclases (sACs) synthesize the ubiquitous second messenger cyclic adenosine 3',5'-monophosphate (cAMP) in response to bicarbonate and calcium signals. Here, we present crystal structures of a cyanobacterial sAC enzyme in complex with ATP analogs, calcium and bicarbonate, which represent distinct catalytic states of the enzyme. The structures reveal that calcium occupies the first ion-binding site and directly mediates nucleotide binding. The single ion-occupied, nucleotide-bound state defines a novel, open adenylyl cyclase state. In contrast, bicarbonate increases the catalytic rate by inducing marked active site closure and recruiting a second, catalytic ion. The phosphates of the bound substrate analogs are rearranged, which would facilitate product formation and release. The mechanisms of calcium and bicarbonate sensing define a reaction pathway involving active site closure and metal recruitment that may be universal for class III cyclases.

PubMed: 15619637
DOI: 10.1038/NSMB880

Experimental method

X-RAY DIFFRACTION (1.93 Å)