Sandbox Reserved 702: Difference between revisions
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===Molecular basis for the activation of edema factor by calmodulin=== | ===Molecular basis for the activation of edema factor by calmodulin=== | ||
<Structure load='1k8t' size='300' frame='true' align='left | <Structure load='1k8t' size='300' frame='true' align='left' /> | ||
<scene name='Sandbox_Reserved_702/1k8t/2'>Structural basis for | <scene name='Sandbox_Reserved_702/1k8t/2'>Structural basis for </scene> the activation of anthrax adenylyl cyclase by calmodulin. (PDB 1k8t)<ref>http://www.rcsb.org/pdb/explore/explore.do?structureId=1k8t</ref> | ||
Legend: {{Template:ColorKey Composition Protein}} | Legend: {{Template:ColorKey Composition Protein}} | ||
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The calcium-free, closed N-terminal domain of [[calmodulin]] binds to the edema factor thanks to an interaction with its helical domain. This interaction is due to '''hydrogen bonds''' and a '''salt bridge''' between helices I and II of the N-terminal domain of [[calmodulin]] and '''helices L and M of the helical domain''' of the edema factor. When the N-terminal domain is noud to the helical domain, the calcium-loaded C-terminal domain in its open conformation inserts between the helical domain and the catalytic core. This allows a conformational change of switch C that will '''stabilize the catalytic loop''' (switch B) of the enzyme in an '''active state'''. A rigid-body rotation of CB relative to CA also occurs. This changes the pocket formed between these two domains and allows the interaction of the edema factor with the phospates of ATP. More precisely, basic lysines of the active site (K346, K353 and K372) are moved upwards. Indeed, the edema factor helical domain undergoes a 15 Å translation and a 30° rotation away from the catalytic core. <ref> PMID: 19560485</ref> <ref> PMID: 15719022</ref> | The calcium-free, closed N-terminal domain of [[calmodulin]] binds to the edema factor thanks to an interaction with its helical domain. This interaction is due to '''hydrogen bonds''' and a '''salt bridge''' between helices I and II of the N-terminal domain of [[calmodulin]] and '''helices L and M of the helical domain''' of the edema factor. When the N-terminal domain is noud to the helical domain, the calcium-loaded C-terminal domain in its open conformation inserts between the helical domain and the catalytic core. This allows a conformational change of switch C that will '''stabilize the catalytic loop''' (switch B) of the enzyme in an '''active state'''. A rigid-body rotation of CB relative to CA also occurs. This changes the pocket formed between these two domains and allows the interaction of the edema factor with the phospates of ATP. More precisely, basic lysines of the active site (K346, K353 and K372) are moved upwards. Indeed, the edema factor helical domain undergoes a 15 Å translation and a 30° rotation away from the catalytic core. <ref> PMID: 19560485</ref> <ref> PMID: 15719022</ref> | ||
==Two magnesium ions are coordinated by the catalytic site== | ==Two magnesium ions are coordinated by the catalytic site== | ||
