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| | {{STRUCTURE_1ykd| PDB=1ykd | SCENE= }} | | {{STRUCTURE_1ykd| PDB=1ykd | SCENE= }} |
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| - | '''Crystal Structure of the Tandem GAF Domains from a Cyanobacterial Adenylyl Cyclase: Novel Modes of Ligand-Binding and Dimerization'''
| + | ===Crystal Structure of the Tandem GAF Domains from a Cyanobacterial Adenylyl Cyclase: Novel Modes of Ligand-Binding and Dimerization=== |
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| - | ==Overview==
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| - | In several species, GAF domains, which are widely expressed small-molecule-binding domains that regulate enzyme activity, are known to bind cyclic nucleotides. However, the molecular mechanism by which cyclic nucleotide binding affects enzyme activity is not known for any GAF domain. In the cyanobacterium, Anabaena, the cyaB1 and cyaB2 genes encode adenylyl cyclases that are stimulated by binding of cAMP to their N-terminal GAF domains. Replacement of the tandem GAF-A/B domains in cyaB1 with the mammalian phosphodiesterase 2A GAF-A/B tandem domains allows regulation of the chimeric protein by cGMP, suggesting a highly conserved mechanism of activation. Here, we describe the 1.9-A crystal structure of the tandem GAF-A/B domains of cyaB2 with bound cAMP and compare it to the previously reported structure of the PDE2A GAF-A/B. Unexpectedly, the cyaB2 GAF-A/B dimer is antiparallel, unlike the parallel dimer of PDE2A. Moreover, there is clear electron density for cAMP in both GAF-A and -B, whereas in PDE2A, cGMP is found only in GAF-B. Phosphate and ribose group contacts are similar to those in PDE2A. However, the purine-binding pockets appear very different from that in PDE2A GAF-B. Differences in the beta2-beta3 loop suggest that this loop confers much of the ligand specificity in this and perhaps in many other GAF domains. Finally, a conserved asparagine appears to be a new addition to the signature NKFDE motif, and a mechanism for this motif to stabilize the cNMP-binding pocket is proposed.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_15708973}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 15708973 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_15708973}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Bound cyclic amp ligand]] | | [[Category: Bound cyclic amp ligand]] |
| | [[Category: Gaf domain]] | | [[Category: Gaf domain]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 16:25:50 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 23:04:09 2008'' |
Revision as of 20:04, 27 July 2008
Template:STRUCTURE 1ykd
Crystal Structure of the Tandem GAF Domains from a Cyanobacterial Adenylyl Cyclase: Novel Modes of Ligand-Binding and Dimerization
Template:ABSTRACT PUBMED 15708973
About this Structure
1YKD is a Single protein structure of sequence from Anabaena sp.. Full crystallographic information is available from OCA.
Reference
Crystal structure of the tandem GAF domains from a cyanobacterial adenylyl cyclase: modes of ligand binding and dimerization., Martinez SE, Bruder S, Schultz A, Zheng N, Schultz JE, Beavo JA, Linder JU, Proc Natl Acad Sci U S A. 2005 Feb 22;102(8):3082-7. Epub 2005 Feb 11. PMID:15708973
Page seeded by OCA on Sun Jul 27 23:04:09 2008
