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| {{STRUCTURE_1ybt| PDB=1ybt | SCENE= }} | | {{STRUCTURE_1ybt| PDB=1ybt | SCENE= }} |
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| '''MYCOBACTERIUM TUBERCULOSIS ADENYLYL CYCLASE, RV1900C CHD'''
| | ===MYCOBACTERIUM TUBERCULOSIS ADENYLYL CYCLASE, RV1900C CHD=== |
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| ==Overview==
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| Rv1900c, a Mycobacterium tuberculosis adenylyl cyclase, is composed of an N-terminal alpha/beta-hydrolase domain and a C-terminal cyclase homology domain. It has an unusual 7% guanylyl cyclase side-activity. A canonical substrate-defining lysine and a catalytic asparagine indispensable for mammalian adenylyl cyclase activity correspond to N342 and H402 in Rv1900c. Mutagenic analysis indicates that these residues are dispensable for activity of Rv1900c. Structures of the cyclase homology domain, solved to 2.4 A both with and without an ATP analog, form isologous, but asymmetric homodimers. The noncanonical N342 and H402 do not interact with the substrate. Subunits of the unliganded open dimer move substantially upon binding substrate, forming a closed dimer similar to the mammalian cyclase heterodimers, in which one interfacial active site is occupied and the quasi-dyad-related active site is occluded. This asymmetry indicates that both active sites cannot simultaneously be catalytically active. Such a mechanism of half-of-sites-reactivity suggests that mammalian heterodimeric adenylyl cyclases may have evolved from gene duplication of a primitive prokaryote-type cyclase, followed by loss of function in one active site.
| | The line below this paragraph, {{ABSTRACT_PUBMED_15678099}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 15678099 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_15678099}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Cyclase homology domain]] | | [[Category: Cyclase homology domain]] |
| [[Category: Rv1900c]] | | [[Category: Rv1900c]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 16:07:25 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 22:11:29 2008'' |
