From Proteopedia
(Difference between revisions)
proteopedia linkproteopedia link
|
|
| Line 1: |
Line 1: |
| - | [[Image:2i2x.gif|left|200px]] | + | {{Seed}} |
| | + | [[Image:2i2x.png|left|200px]] |
| | | | |
| | <!-- | | <!-- |
| Line 9: |
Line 10: |
| | {{STRUCTURE_2i2x| PDB=2i2x | SCENE= }} | | {{STRUCTURE_2i2x| PDB=2i2x | SCENE= }} |
| | | | |
| - | '''Crystal structure of methanol:cobalamin methyltransferase complex MtaBC from Methanosarcina barkeri'''
| + | ===Crystal structure of methanol:cobalamin methyltransferase complex MtaBC from Methanosarcina barkeri=== |
| | | | |
| | | | |
| - | ==Overview==
| + | <!-- |
| - | Some methanogenic and acetogenic microorganisms have the catalytic capability to cleave heterolytically the C O bond of methanol. To obtain insight into the elusive enzymatic mechanism of this challenging chemical reaction we have investigated the methanol-activating MtaBC complex from Methanosarcina barkeri composed of the zinc-containing MtaB and the 5-hydroxybenzimidazolylcobamide-carrying MtaC subunits. Here we report the 2.5-A crystal structure of this complex organized as a (MtaBC)(2) heterotetramer. MtaB folds as a TIM barrel and contains a novel zinc-binding motif. Zinc(II) lies at the bottom of a funnel formed at the C-terminal beta-barrel end and ligates to two cysteinyl sulfurs (Cys-220 and Cys-269) and one carboxylate oxygen (Glu-164). MtaC is structurally related to the cobalamin-binding domain of methionine synthase. Its corrinoid cofactor at the top of the Rossmann domain reaches deeply into the funnel of MtaB, defining a region between zinc(II) and the corrinoid cobalt that must be the binding site for methanol. The active site geometry supports a S(N)2 reaction mechanism, in which the C O bond in methanol is activated by the strong electrophile zinc(II) and cleaved because of an attack of the supernucleophile cob(I)amide. The environment of zinc(II) is characterized by an acidic cluster that increases the charge density on the zinc(II), polarizes methanol, and disfavors deprotonation of the methanol hydroxyl group. Implications of the MtaBC structure for the second step of the reaction, in which the methyl group is transferred to coenzyme M, are discussed.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_17142327}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 17142327 is the PubMed ID number. |
| | + | --> |
| | + | {{ABSTRACT_PUBMED_17142327}} |
| | | | |
| | ==About this Structure== | | ==About this Structure== |
| Line 29: |
Line 33: |
| | [[Category: Warkentin, E.]] | | [[Category: Warkentin, E.]] |
| | [[Category: Transferase]] | | [[Category: Transferase]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Apr 30 13:25:39 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 07:12:37 2008'' |
Revision as of 04:12, 28 July 2008
Template:STRUCTURE 2i2x
Crystal structure of methanol:cobalamin methyltransferase complex MtaBC from Methanosarcina barkeri
Template:ABSTRACT PUBMED 17142327
About this Structure
2I2X is a Protein complex structure of sequences from Methanosarcina barkeri. Full crystallographic information is available from OCA.
Reference
Insight into the mechanism of biological methanol activation based on the crystal structure of the methanol-cobalamin methyltransferase complex., Hagemeier CH, Krer M, Thauer RK, Warkentin E, Ermler U, Proc Natl Acad Sci U S A. 2006 Dec 12;103(50):18917-22. Epub 2006 Dec 1. PMID:17142327
Page seeded by OCA on Mon Jul 28 07:12:37 2008
