1wc1
SOLUBLE ADENYLYL CYCLASE CYAC FROM S. PLATENSIS IN COMPLEX WITH RP-ATPALPHAS
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| , resolution 1.93Å | |||||||
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| Sites: | |||||||
| Ligands: | , | ||||||
| Activity: | Adenylate cyclase, with EC number 4.6.1.1 | ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
OverviewOverview
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.
About this StructureAbout this Structure
1WC1 is a Single protein structure of sequence from Arthrospira platensis. Full crystallographic information is available from OCA.
ReferenceReference
Bicarbonate activation of adenylyl cyclase via promotion of catalytic active site closure and metal recruitment., Steegborn C, Litvin TN, Levin LR, Buck J, Wu H, Nat Struct Mol Biol. 2005 Jan;12(1):32-7. Epub 2004 Dec 26. PMID:15619637
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