1qgn
From Proteopedia
(New page: 200px<br /><applet load="1qgn" size="450" color="white" frame="true" align="right" spinBox="true" caption="1qgn, resolution 2.9Å" /> '''CYSTATHIONINE GAMMA-S...) |
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| - | [[Image:1qgn.jpg|left|200px]]<br /><applet load="1qgn" size=" | + | [[Image:1qgn.jpg|left|200px]]<br /><applet load="1qgn" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1qgn, resolution 2.9Å" /> | caption="1qgn, resolution 2.9Å" /> | ||
'''CYSTATHIONINE GAMMA-SYNTHASE FROM NICOTIANA TABACUM'''<br /> | '''CYSTATHIONINE GAMMA-SYNTHASE FROM NICOTIANA TABACUM'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Cystathionine gamma-synthase catalyses the committed step of de novo | + | Cystathionine gamma-synthase catalyses the committed step of de novo methionine biosynthesis in micro-organisms and plants, making the enzyme an attractive target for the design of new antibiotics and herbicides. The crystal structure of cystathionine gamma-synthase from Nicotiana tabacum has been solved by Patterson search techniques using the structure of Escherichia coli cystathionine gamma-synthase. The model was refined at 2.9 A resolution to a crystallographic R -factor of 20.1 % (Rfree25.0 %). The physiological substrates of the enzyme, L-homoserine phosphate and L-cysteine, were modelled into the unliganded structure. These complexes support the proposed ping-pong mechanism for catalysis and illustrate the dissimilar substrate specificities of bacterial and plant cystathionine gamma-synthases on a molecular level. The main difference arises from the binding modes of the distal substrate groups (O -acetyl/succinyl versusO -phosphate). Central in fixing the distal phosphate of the plant CGS substrate is an exposed lysine residue that is strictly conserved in plant cystathionine gamma-synthases whereas bacterial enzymes carry a glycine residue at this position. General insight regarding the reaction specificity of transsulphuration enzymes is gained by the comparison to cystathionine beta-lyase from E. coli, indicating the mechanistic importance of a second substrate binding site for L-cysteine which leads to different chemical reaction types. |
==About this Structure== | ==About this Structure== | ||
| - | 1QGN is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Nicotiana_tabacum Nicotiana tabacum] with PLP as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Cystathionine_gamma-synthase Cystathionine gamma-synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.5.1.48 2.5.1.48] Full crystallographic information is available from [http:// | + | 1QGN is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Nicotiana_tabacum Nicotiana tabacum] with <scene name='pdbligand=PLP:'>PLP</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Cystathionine_gamma-synthase Cystathionine gamma-synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.5.1.48 2.5.1.48] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QGN OCA]. |
==Reference== | ==Reference== | ||
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[[Category: pyridoxal 5'-phosphate]] | [[Category: pyridoxal 5'-phosphate]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:39:18 2008'' |
Revision as of 12:39, 21 February 2008
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CYSTATHIONINE GAMMA-SYNTHASE FROM NICOTIANA TABACUM
Overview
Cystathionine gamma-synthase catalyses the committed step of de novo methionine biosynthesis in micro-organisms and plants, making the enzyme an attractive target for the design of new antibiotics and herbicides. The crystal structure of cystathionine gamma-synthase from Nicotiana tabacum has been solved by Patterson search techniques using the structure of Escherichia coli cystathionine gamma-synthase. The model was refined at 2.9 A resolution to a crystallographic R -factor of 20.1 % (Rfree25.0 %). The physiological substrates of the enzyme, L-homoserine phosphate and L-cysteine, were modelled into the unliganded structure. These complexes support the proposed ping-pong mechanism for catalysis and illustrate the dissimilar substrate specificities of bacterial and plant cystathionine gamma-synthases on a molecular level. The main difference arises from the binding modes of the distal substrate groups (O -acetyl/succinyl versusO -phosphate). Central in fixing the distal phosphate of the plant CGS substrate is an exposed lysine residue that is strictly conserved in plant cystathionine gamma-synthases whereas bacterial enzymes carry a glycine residue at this position. General insight regarding the reaction specificity of transsulphuration enzymes is gained by the comparison to cystathionine beta-lyase from E. coli, indicating the mechanistic importance of a second substrate binding site for L-cysteine which leads to different chemical reaction types.
About this Structure
1QGN is a Single protein structure of sequence from Nicotiana tabacum with as ligand. Active as Cystathionine gamma-synthase, with EC number 2.5.1.48 Full crystallographic information is available from OCA.
Reference
The crystal structure of cystathionine gamma-synthase from Nicotiana tabacum reveals its substrate and reaction specificity., Steegborn C, Messerschmidt A, Laber B, Streber W, Huber R, Clausen T, J Mol Biol. 1999 Jul 30;290(5):983-96. PMID:10438597
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