6a0k

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<StructureSection load='6a0k' size='340' side='right' caption='[[6a0k]], [[Resolution|resolution]] 1.94&Aring;' scene=''>
<StructureSection load='6a0k' size='340' side='right' caption='[[6a0k]], [[Resolution|resolution]] 1.94&Aring;' scene=''>
== Structural highlights ==
== Structural highlights ==
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<table><tr><td colspan='2'>[[6a0k]] is a 2 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6A0K OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6A0K FirstGlance]. <br>
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<table><tr><td colspan='2'>[[6a0k]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/"achromobacter_globiformis"_(conn_1928)_bergey_et_al._1930 "achromobacter globiformis" (conn 1928) bergey et al. 1930]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6A0K OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6A0K FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=BGC:BETA-D-GLUCOSE'>BGC</scene>, <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=GLC:ALPHA-D-GLUCOSE'>GLC</scene></td></tr>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=BGC:BETA-D-GLUCOSE'>BGC</scene>, <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=GLC:ALPHA-D-GLUCOSE'>GLC</scene></td></tr>
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<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">cmmF ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=1665 "Achromobacter globiformis" (Conn 1928) Bergey et al. 1930])</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=6a0k FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6a0k OCA], [http://pdbe.org/6a0k PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6a0k RCSB], [http://www.ebi.ac.uk/pdbsum/6a0k PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6a0k 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=6a0k FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6a0k OCA], [http://pdbe.org/6a0k PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6a0k RCSB], [http://www.ebi.ac.uk/pdbsum/6a0k PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6a0k ProSAT]</span></td></tr>
</table>
</table>
<div style="background-color:#fffaf0;">
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
== Publication Abstract from PubMed ==
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Cyclic maltosyl-maltose [CMM, cyclo-[--&gt;6)-alpha-D-Glcp-(1--&gt;4)-alpha-D-Glcp-(1--&gt;6)-alpha-D-Glcp-(1--&gt;4)-alpha -D-Glcp-(1--&gt;]], a novel cyclic tetrasaccharide, has a unique structure. Its four glucose residues are joined by alternate alpha-1,4 and alpha-1,6 linkages. CMM is synthesized from starch by the action of 6-alpha-maltosyltransferase from Arthrobacter globiformis M6. Recently, we determined the mechanism of extracellular synthesis of CMM, but the degrading pathway of the saccharide remains unknown. Hence we tried to identify the enzymes involved in the degradation of CMM to glucose from the cell-free extract of the strain, and identified CMM hydrolase (CMMase) and alpha-glucosidase as the responsible enzymes. The molecular mass of CMMase was determined to be 48.6 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and 136 kDa by gel filtration column chromatography. The optimal pH and temperature for CMMase activity were 6.5 and 30 degrees C. The enzyme remained stable from pH 5.5 to 8.0 and up to 25 degrees C. CMMase hydrolyzed CMM to maltose via maltosyl-maltose as intermediates, but it did not hydrolyze CMM to glucose, suggesting that it is a novel hydrolase that hydrolyzes the alpha-1,6-linkage of CMM. The molecular mass of alpha-glucosidase was determined to be 60.1 kDa by SDS-PAGE and 69.5 kDa by gel filtration column chromatography. The optimal pH and temperature for alpha-glucosidase activity were 7.0 and 35 degrees C. The enzyme remained stable from pH 7.0 to 9.5 and up to 35 degrees C. alpha-Glucosidase degraded maltosyl-maltose to glucose via panose and maltose as intermediates, but it did not degrade CMM. Furthermore, when CMMase and alpha-glucosidase existed simultaneously in a reaction mixture containing CMM, glucose was detected as the final product. It was found that CMM was degraded to glucose by the synergistic action of CMMase and alpha-glucosidase.
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Cyclic alpha-maltosyl-(1--&gt;6)-maltose (CMM,cyclo-{--&gt;6)-alpha-d-Glcp-(1--&gt;4)-alpha-d-Glcp-(1--&gt;6)-alpha-d-Glcp-(1--&gt;4)- alpha-d-Glcp-(1--&gt;}) is a cyclic glucotetrasaccharide with alternating alpha-1,4 and alpha-1,6 linkages. CMM is composed of two maltose units and is one of the smallest cyclic glucooligosaccharides. While CMM is resistant to usual amylases, it is efficiently hydrolyzed by CMM hydrolase (CMMase), belonging to subfamily 20 of glycoside hydrolase family 13 (GH13_20). Here, we determined the ligand-free crystal structure of CMMase from the soil-associated bacterium Arthrobacter globiformis and its structures in complex with maltose, panose, and CMM to elucidate the structural basis of substrate recognition by CMMase. The structures disclosed that although the monomer structure consists of three domains commonly adopted by GH13 and other alpha-amylase-related enzymes, CMMase forms a unique wing-like dimer structure. The complex structure with CMM revealed four specific subsites, namely, -3', -2, -1, and +1'. We also observed that the bound CMM molecule adopts a low-energy conformer compared with the X-ray structure of a single CMM crystal, also determined here. Comparison of the CMMase active site with those in other enzymes of the GH13_20 family revealed that three regions forming the wall of the cleft, denoted PYF (Pro-203/Tyr-204/Phe-205), CS (Cys-163/Ser-164), and Y (Tyr-168), are present only in CMMase and are involved in CMM recognition. Combinations of multiple substitutions in these regions markedly decreased the activity toward CMM, indicating that the specificity for this cyclic tetrasaccharide is supported by the entire shape of the pocket. In summary, our work uncovers the mechanistical basis for the highly specific interactions of CMMase with its substrate CMM.
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Purification and characterization of cyclic maltosyl-(1--&gt;6)-maltose hydrolase and alpha-glucosidase from an Arthrobacter globiformis strain.,Mori T, Nishimoto T, Okura T, Chaen H, Fukuda S Biosci Biotechnol Biochem. 2008 Jul;72(7):1673-81. doi: 10.1271/bbb.70759. Epub, 2008 Jul 7. PMID:18603794<ref>PMID:18603794</ref>
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Structural features of a bacterial cyclic alpha-maltosyl-(1--&gt;6)-maltose (CMM) hydrolase critical for CMM recognition and hydrolysis.,Kohno M, Arakawa T, Ota H, Mori T, Nishimoto T, Fushinobu S J Biol Chem. 2018 Sep 4. pii: RA118.004472. doi: 10.1074/jbc.RA118.004472. PMID:30181215<ref>PMID:30181215</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

Revision as of 20:14, 19 September 2018

Cyclic alpha-maltosyl-(1-->6)-maltose hydrolase from Arthrobacter globiformis, complex with panose

6a0k, resolution 1.94Å

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