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| | ==Crystal Structure of the periplasmic alginate epimerase AlgG== | | ==Crystal Structure of the periplasmic alginate epimerase AlgG== |
| - | <StructureSection load='4nk6' size='340' side='right' caption='[[4nk6]], [[Resolution|resolution]] 2.10Å' scene=''> | + | <StructureSection load='4nk6' size='340' side='right'caption='[[4nk6]], [[Resolution|resolution]] 2.10Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[4nk6]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Psesm Psesm]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4NK6 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4NK6 FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[4nk6]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Pseudomonas_syringae_pv._tomato_str._DC3000 Pseudomonas syringae pv. tomato str. DC3000]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4NK6 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4NK6 FirstGlance]. <br> |
| - | </td></tr><tr id='NonStdRes'><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=MLY:N-DIMETHYL-LYSINE'>MLY</scene></td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.0974Å</td></tr> |
| - | <tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[4nk8|4nk8]]</td></tr> | + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MLY:N-DIMETHYL-LYSINE'>MLY</scene></td></tr> |
| - | <tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">algG, PSPTO_1238 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=223283 PSESM])</td></tr>
| + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=4nk6 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4nk6 OCA], [https://pdbe.org/4nk6 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4nk6 RCSB], [https://www.ebi.ac.uk/pdbsum/4nk6 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4nk6 ProSAT]</span></td></tr> |
| - | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4nk6 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4nk6 OCA], [http://pdbe.org/4nk6 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=4nk6 RCSB], [http://www.ebi.ac.uk/pdbsum/4nk6 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=4nk6 ProSAT]</span></td></tr> | + | |
| | </table> | | </table> |
| | == Function == | | == Function == |
| - | [[http://www.uniprot.org/uniprot/ALGG_PSESM ALGG_PSESM]] Bifunctional protein that converts poly(beta-D-mannuronate) to alpha-L-guluronate and that is also part of a periplasmic protein complex that serves as a scaffold that leads the newly formed alginate polymer through the periplasmic space to the outer membrane secretin AlgE (By similarity). | + | [https://www.uniprot.org/uniprot/ALGG_PSESM ALGG_PSESM] Bifunctional protein that converts poly(beta-D-mannuronate) to alpha-L-guluronate and that is also part of a periplasmic protein complex that serves as a scaffold that leads the newly formed alginate polymer through the periplasmic space to the outer membrane secretin AlgE (By similarity). |
| | <div style="background-color:#fffaf0;"> | | <div style="background-color:#fffaf0;"> |
| | == Publication Abstract from PubMed == | | == Publication Abstract from PubMed == |
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| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Psesm]] | + | [[Category: Large Structures]] |
| - | [[Category: Howell, P L]] | + | [[Category: Pseudomonas syringae pv. tomato str. DC3000]] |
| - | [[Category: Robinson, H]] | + | [[Category: Howell PL]] |
| - | [[Category: Wolfram, F]] | + | [[Category: Robinson H]] |
| - | [[Category: Algg]] | + | [[Category: Wolfram F]] |
| - | [[Category: Alginate]]
| + | |
| - | [[Category: Isomerase]]
| + | |
| - | [[Category: Lysine methylation]]
| + | |
| - | [[Category: Mannuronate]]
| + | |
| - | [[Category: Parallel beta-helix]]
| + | |
| - | [[Category: Polysaccharide epimerase]]
| + | |
| - | [[Category: Pseudomona]]
| + | |
| Structural highlights
Function
ALGG_PSESM Bifunctional protein that converts poly(beta-D-mannuronate) to alpha-L-guluronate and that is also part of a periplasmic protein complex that serves as a scaffold that leads the newly formed alginate polymer through the periplasmic space to the outer membrane secretin AlgE (By similarity).
Publication Abstract from PubMed
Pseudomonas aeruginosa is an opportunistic pathogen that forms chronic biofilm infections in the lungs of cystic fibrosis patients. A major component of the biofilm during these infections is the exopolysaccharide alginate, which is synthesized at the inner membrane as a homopolymer of 1-4-linked beta-D-mannuronate. As the polymer passages through the periplasm 22-44% of the mannuronate residues are converted to alpha-L-guluronate by the C5 epimerase AlgG to produce a polymer of alternating beta-D-mannuronate and alpha-L-guluronate blocks and stretches of polymannuronate. To understand the molecular basis of alginate epimerization the structure of Pseudomonas syringae AlgG has been determined at 2.1A resolution and the protein functionally characterized. The structure reveals that AlgG is a long right-handed parallel beta-helix with an elaborate lid structure. Functional analysis of AlgG mutants suggest that His319 acts as the catalytic base, and that Arg345 neutralizes the acidic group during the epimerase reaction. Water is the likely catalytic acid. Electrostatic surface potential and residue conservation analysis, in conjunction with activity and substrate docking studies, suggest that a conserved electropositive groove facilitates polymannuronate binding and contains at least nine substrate binding subsites. These subsites likely align the polymer in the correct register for catalysis to occur. The presence of multiple subsites, the electropositive groove and the non-random distribution of guluronate in the alginate polymer suggest that AlgG is a processive enzyme. Moreover, comparison of AlgG and the extracellular alginate epimerase AlgE4 of A. vinelandii provides a structural rationale for the differences in their Ca2+ dependency.
Catalytic mechanism and mode of action of the periplasmic alginate epimerase AlgG.,Wolfram F, Kitova EN, Robinson H, Walvoort M, Codee JD, Klassen JS, Howell PL J Biol Chem. 2014 Jan 7. PMID:24398681[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Wolfram F, Kitova EN, Robinson H, Walvoort M, Codee JD, Klassen JS, Howell PL. Catalytic mechanism and mode of action of the periplasmic alginate epimerase AlgG. J Biol Chem. 2014 Jan 7. PMID:24398681 doi:http://dx.doi.org/10.1074/jbc.M113.533158
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