1pmj
From Proteopedia
OCA (Talk | contribs)
(New page: 200px<br /><applet load="1pmj" size="450" color="white" frame="true" align="right" spinBox="true" caption="1pmj, resolution 1.55Å" /> '''Crystal structure of...)
Next diff →
Revision as of 00:34, 25 November 2007
|
Crystal structure of Caldicellulosiruptor saccharolyticus CBM27-1
Overview
Carbohydrate-binding modules (CBMs) are the most common non-catalytic, modules associated with enzymes active in plant cell-wall hydrolysis., Despite the large number of putative CBMs being identified by amino acid, sequence alignments, only few representatives have been experimentally, shown to have a carbohydrate-binding function. Caldicellulosiruptor strain, Rt8B.4 Man26 is a thermostable modular glycoside hydrolase beta-mannanase, which contains two non-catalytic modules in tandem at its N terminus., These modules were recently shown to function primarily as, beta-mannan-binding modules and have accordingly been classified as, members of a novel family of CBMs, family 27. The N-terminal CBM27, (CsCBM27-1) of Man26 from Caldicellulosiruptor Rt8B.4 displays, high-binding affinity towards mannohexaose with a Ka of 1 x 10(7) M(-1)., Accordingly, the high-resolution crystal structures of CsCBM27-1 native, and its mannohexaose complex were solved at 1.55 angstroms and 1.06, angstoms resolution, respectively. In the crystal, CsCBM27-1 shows the, typical beta-sandwich jellyroll fold observed in other CBMs with a single, metal ion bound, which was identified as calcium. The crystal structures, reveal that the overall fold of CsCBM27-1 remains virtually unchanged upon, sugar binding and that binding is mediated by three solvent-exposed, tryptophan residues and few direct hydrogen bonds. Based on binding, affinity and thermal unfolding experiments this structural calcium is, shown to play a role in the thermal stability of CsCBM27-1 at high, temperatures. The higher binding affinity of CsCBM27-1 to, mannooligosaccharides when compared to other members of CBM family 27, might be explained by the different orientation of the residues forming, the "aromatic platform" and by differences in the length of loops., Finally, evidence is presented, on the basis of fold similarities and the, retention of the position of conserved motifs and a calcium ion, for the, consolidation of related CBM families into a superfamily of CBMs.
About this Structure
1PMJ is a Single protein structure of sequence from Caldicellulosiruptor saccharolyticus with CA, EDO and ACY as ligands. Active as Mannan endo-1,4-beta-mannosidase, with EC number 3.2.1.78 Full crystallographic information is available from OCA.
Reference
High-resolution crystal structures of Caldicellulosiruptor strain Rt8B.4 carbohydrate-binding module CBM27-1 and its complex with mannohexaose., Roske Y, Sunna A, Pfeil W, Heinemann U, J Mol Biol. 2004 Jul 9;340(3):543-54. PMID:15210353
Page seeded by OCA on Sun Nov 25 02:42:28 2007
