4ak6: Difference between revisions
No edit summary |
No edit summary |
||
| Line 1: | Line 1: | ||
[[ | ==BpGH117_H302E mutant glycoside hydrolase== | ||
<StructureSection load='4ak6' size='340' side='right' caption='[[4ak6]], [[Resolution|resolution]] 1.90Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[4ak6]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Bacteroides_plebeius Bacteroides plebeius]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4AK6 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4AK6 FirstGlance]. <br> | |||
</td></tr><tr><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene><br> | |||
<tr><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[4ak5|4ak5]], [[4ak7|4ak7]]</td></tr> | |||
<tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4ak6 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4ak6 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=4ak6 RCSB], [http://www.ebi.ac.uk/pdbsum/4ak6 PDBsum]</span></td></tr> | |||
<table> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
Agars are abundant polysaccharides from marine red algae and their chemical structure consists of alternating D- galactose and 3,6-anhydro-L-galactose residues, the latter of which is presumed to make the polymer recalcitrant to degradation by most terrestrial bacteria. Here we study a family 117 glycoside hydrolase (BpGH117) encoded within a recently discovered locus from the human gut bacterium Bacteroides plebeius. Consistent with this locus being involved in agarocolloid degradation, we show BpGH117 is an exo-acting 3,6-anhydro-alpha-(1,3)-L-galactosidase that removes the 3,6-anhydro-galactose from the non-reducing end of neoagaro-oligosaccharides. A Michaelis-complex of BpGH117 with neoagarobiose reveals the distortion of the constrained 3,6-anhydro-L-galactose into a conformation that favours catalysis. Furthermore, this complex, supported by analysis of site-directed mutants, provides evidence for and organization of the active site and positioning of the catalytic residues that is consistent with an inverting mechanism of catalysis and suggests that a histidine residue acts as the general acid. This latter feature differs from the vast majority of glycoside hydrolases, which use a carboxylic acid, highlighting the alternative strategies that enzymes may employ in catalyzing the cleavage of glycosidic bonds. | |||
Analysis of a keystone enzyme in agar hydrolysis provides insight into polysaccharide degradation from red seaweeds.,Hehemann JH, Smyth L, Yadav A, Vocadlo DJ, Boraston AB J Biol Chem. 2012 Mar 5. PMID:22393053<ref>PMID:22393053</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
==See Also== | |||
*[[Galactosidase|Galactosidase]] | |||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
== | |||
[[ | |||
== | |||
< | |||
[[Category: Bacteroides plebeius]] | [[Category: Bacteroides plebeius]] | ||
[[Category: Boraston, A B.]] | [[Category: Boraston, A B.]] | ||