2isq
From Proteopedia
(New page: 200px<br /><applet load="2isq" size="450" color="white" frame="true" align="right" spinBox="true" caption="2isq, resolution 2.8Å" /> '''Crystal Structure of ...) |
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| - | [[Image:2isq.jpg|left|200px]]<br /><applet load="2isq" size=" | + | [[Image:2isq.jpg|left|200px]]<br /><applet load="2isq" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2isq, resolution 2.8Å" /> | caption="2isq, resolution 2.8Å" /> | ||
'''Crystal Structure of O-Acetylserine Sulfhydrylase from Arabidopsis Thaliana in Complex with C-Terminal Peptide from Arabidopsis Serine Acetyltransferase'''<br /> | '''Crystal Structure of O-Acetylserine Sulfhydrylase from Arabidopsis Thaliana in Complex with C-Terminal Peptide from Arabidopsis Serine Acetyltransferase'''<br /> | ||
==Overview== | ==Overview== | ||
| - | In plants, association of O-acetylserine sulfhydrylase (OASS) and Ser | + | In plants, association of O-acetylserine sulfhydrylase (OASS) and Ser acetyltransferase (SAT) into the Cys synthase complex plays a regulatory role in sulfur assimilation and Cys biosynthesis. We determined the crystal structure of Arabidopsis thaliana OASS (At-OASS) bound with a peptide corresponding to the C-terminal 10 residues of Arabidopsis SAT (C10 peptide) at 2.9-A resolution. Hydrogen bonding interactions with key active site residues (Thr-74, Ser-75, and Gln-147) lock the C10 peptide in the binding site. C10 peptide binding blocks access to OASS catalytic residues, explaining how complex formation downregulates OASS activity. Comparison with bacterial OASS suggests that structural plasticity in the active site allows binding of SAT C termini with dissimilar sequences at structurally similar OASS active sites. Calorimetric analysis of the effect of active site mutations (T74S, S75A, S75T, and Q147A) demonstrates that these residues are important for C10 peptide binding and that changes at these positions disrupt communication between active sites in the homodimeric enzyme. We also demonstrate that the C-terminal Ile of the C10 peptide is required for molecular recognition by At-OASS. These results provide new insights into the molecular mechanism underlying formation of the Cys synthase complex and provide a structural basis for the biochemical regulation of Cys biosynthesis in plants. |
==About this Structure== | ==About this Structure== | ||
| - | 2ISQ is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Arabidopsis_thaliana Arabidopsis thaliana] with SO4 and PLP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cysteine_synthase Cysteine synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.5.1.47 2.5.1.47] Full crystallographic information is available from [http:// | + | 2ISQ is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Arabidopsis_thaliana Arabidopsis thaliana] with <scene name='pdbligand=SO4:'>SO4</scene> and <scene name='pdbligand=PLP:'>PLP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cysteine_synthase Cysteine synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.5.1.47 2.5.1.47] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2ISQ OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Cysteine synthase]] | [[Category: Cysteine synthase]] | ||
[[Category: Protein complex]] | [[Category: Protein complex]] | ||
| - | [[Category: Francois, J | + | [[Category: Francois, J A.]] |
| - | [[Category: Jez, J | + | [[Category: Jez, J M.]] |
[[Category: Kumaran, S.]] | [[Category: Kumaran, S.]] | ||
[[Category: PLP]] | [[Category: PLP]] | ||
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[[Category: alpha beta structrual domain]] | [[Category: alpha beta structrual domain]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:55:32 2008'' |
Revision as of 15:55, 21 February 2008
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Crystal Structure of O-Acetylserine Sulfhydrylase from Arabidopsis Thaliana in Complex with C-Terminal Peptide from Arabidopsis Serine Acetyltransferase
Overview
In plants, association of O-acetylserine sulfhydrylase (OASS) and Ser acetyltransferase (SAT) into the Cys synthase complex plays a regulatory role in sulfur assimilation and Cys biosynthesis. We determined the crystal structure of Arabidopsis thaliana OASS (At-OASS) bound with a peptide corresponding to the C-terminal 10 residues of Arabidopsis SAT (C10 peptide) at 2.9-A resolution. Hydrogen bonding interactions with key active site residues (Thr-74, Ser-75, and Gln-147) lock the C10 peptide in the binding site. C10 peptide binding blocks access to OASS catalytic residues, explaining how complex formation downregulates OASS activity. Comparison with bacterial OASS suggests that structural plasticity in the active site allows binding of SAT C termini with dissimilar sequences at structurally similar OASS active sites. Calorimetric analysis of the effect of active site mutations (T74S, S75A, S75T, and Q147A) demonstrates that these residues are important for C10 peptide binding and that changes at these positions disrupt communication between active sites in the homodimeric enzyme. We also demonstrate that the C-terminal Ile of the C10 peptide is required for molecular recognition by At-OASS. These results provide new insights into the molecular mechanism underlying formation of the Cys synthase complex and provide a structural basis for the biochemical regulation of Cys biosynthesis in plants.
About this Structure
2ISQ is a Protein complex structure of sequences from Arabidopsis thaliana with and as ligands. Active as Cysteine synthase, with EC number 2.5.1.47 Full crystallographic information is available from OCA.
Reference
Structural basis for interaction of O-acetylserine sulfhydrylase and serine acetyltransferase in the Arabidopsis cysteine synthase complex., Francois JA, Kumaran S, Jez JM, Plant Cell. 2006 Dec;18(12):3647-55. Epub 2006 Dec 28. PMID:17194764
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