1ssq
From Proteopedia
(New page: 200px<br /><applet load="1ssq" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ssq, resolution 1.85Å" /> '''Serine Acetyltransfe...) |
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| - | [[Image:1ssq.gif|left|200px]]<br /><applet load="1ssq" size=" | + | [[Image:1ssq.gif|left|200px]]<br /><applet load="1ssq" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1ssq, resolution 1.85Å" /> | caption="1ssq, resolution 1.85Å" /> | ||
'''Serine Acetyltransferase- Complex with Cysteine'''<br /> | '''Serine Acetyltransferase- Complex with Cysteine'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Serine acetyltransferase (SAT, EC 2.3.1.30) catalyzes the CoA-dependent | + | Serine acetyltransferase (SAT, EC 2.3.1.30) catalyzes the CoA-dependent acetylation of the side chain hydroxyl group of l-serine to form O-acetylserine, as the first step of a two-step biosynthetic pathway in bacteria and plants leading to the formation of l-cysteine. This reaction represents a key metabolic point of regulation for the cysteine biosynthetic pathway due to its feedback inhibition by cysteine. We have determined the X-ray crystal structure of Haemophilus influenzae SAT in complexes with CoA and its cysteine feedback inhibitor. The enzyme is a 175 kDa hexamer displaying the characteristic left-handed parallel beta-helix (LbetaH) structural domain of the hexapeptide acyltransferase superfamily of enzymes. Cysteine is bound in a crevice between adjacent LbetaH domains and underneath a loop excluded from the coiled LbetaH. The proximity of its thiol group to the thiol group of CoA derived from superimposed models of the cysteine and CoA complexes confirms that cysteine is bound at the active site. Analysis of the contacts of SAT with cysteine and CoA and the conformational differences that distinguish these complexes provides a structural basis for cysteine feedback inhibition, which invokes competition between cysteine and serine binding and a cysteine-induced conformational change of the C-terminal segment of the enzyme that excludes binding of the cofactor. |
==About this Structure== | ==About this Structure== | ||
| - | 1SSQ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Haemophilus_influenzae Haemophilus influenzae] with MG and CYS as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Serine_O-acetyltransferase Serine O-acetyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.3.1.30 2.3.1.30] Full crystallographic information is available from [http:// | + | 1SSQ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Haemophilus_influenzae Haemophilus influenzae] with <scene name='pdbligand=MG:'>MG</scene> and <scene name='pdbligand=CYS:'>CYS</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Serine_O-acetyltransferase Serine O-acetyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.3.1.30 2.3.1.30] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SSQ OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Huang, B.]] | [[Category: Huang, B.]] | ||
| - | [[Category: Olsen, L | + | [[Category: Olsen, L R.]] |
| - | [[Category: Roderick, S | + | [[Category: Roderick, S L.]] |
| - | [[Category: Vetting, M | + | [[Category: Vetting, M W.]] |
[[Category: CYS]] | [[Category: CYS]] | ||
[[Category: MG]] | [[Category: MG]] | ||
[[Category: left-handed parallel beta helix]] | [[Category: left-handed parallel beta helix]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:04:48 2008'' |
Revision as of 13:04, 21 February 2008
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Serine Acetyltransferase- Complex with Cysteine
Overview
Serine acetyltransferase (SAT, EC 2.3.1.30) catalyzes the CoA-dependent acetylation of the side chain hydroxyl group of l-serine to form O-acetylserine, as the first step of a two-step biosynthetic pathway in bacteria and plants leading to the formation of l-cysteine. This reaction represents a key metabolic point of regulation for the cysteine biosynthetic pathway due to its feedback inhibition by cysteine. We have determined the X-ray crystal structure of Haemophilus influenzae SAT in complexes with CoA and its cysteine feedback inhibitor. The enzyme is a 175 kDa hexamer displaying the characteristic left-handed parallel beta-helix (LbetaH) structural domain of the hexapeptide acyltransferase superfamily of enzymes. Cysteine is bound in a crevice between adjacent LbetaH domains and underneath a loop excluded from the coiled LbetaH. The proximity of its thiol group to the thiol group of CoA derived from superimposed models of the cysteine and CoA complexes confirms that cysteine is bound at the active site. Analysis of the contacts of SAT with cysteine and CoA and the conformational differences that distinguish these complexes provides a structural basis for cysteine feedback inhibition, which invokes competition between cysteine and serine binding and a cysteine-induced conformational change of the C-terminal segment of the enzyme that excludes binding of the cofactor.
About this Structure
1SSQ is a Single protein structure of sequence from Haemophilus influenzae with and as ligands. Active as Serine O-acetyltransferase, with EC number 2.3.1.30 Full crystallographic information is available from OCA.
Reference
Structure of serine acetyltransferase in complexes with CoA and its cysteine feedback inhibitor., Olsen LR, Huang B, Vetting MW, Roderick SL, Biochemistry. 2004 May 25;43(20):6013-9. PMID:15147185
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