Structural insights into the inhibition of cellobiohydrolase Cel7A by xylo‐oligosaccharides. (8th April 2015)

• Record Type: Journal Article
• Authors: Momeni, Majid Haddad; Ubhayasekera, Wimal; Sandgren, Mats; Ståhlberg, Jerry; Hansson, Henrik
• Is Part Of: FEBS journal. Volume 282:Number 11(2015)
• Page Start: 2167
• Page End: 2177
• Publication Date: 2015-04-08
• Subjects: Biochemistry -- Periodicals; Molecular biology -- Periodicals; Pathology, Molecular -- Periodicals; 572
• DOI: 10.1111/febs.13265
• Languages: English
• ISSNs: 1742-464X

Abstract

<abstract abstract-type="main" id="febs13265-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="febs13265-sec-0001" sec-type="section"> <p>The filamentous fungus <italic>Hypocrea jecorina</italic> (anamorph of <italic>Trichoderma reesei</italic>) is the predominant source of enzymes for industrial saccharification of lignocellulose biomass. The major enzyme, cellobiohydrolase Cel7A, constitutes nearly half of the total protein in the secretome. The performance of such enzymes is susceptible to inhibition by compounds liberated by physico‐chemical pre‐treatment if the biomass is kept unwashed. Xylan and xylo‐oligosaccharides (XOS) have been proposed to play a key role in inhibition of cellobiohydrolases of glycoside hydrolase family 7. To elucidate the mechanism behind this inhibition at a molecular level, we used X‐ray crystallography to determine structures of <italic>H. jecorina</italic> Cel7A in complex with XOS. Structures with xylotriose, xylotetraose and xylopentaose revealed a predominant binding mode at the entrance of the substrate‐binding tunnel of the enzyme, in which each xylose residue is shifted ~ 2.4 Å towards the catalytic center compared with binding of cello‐oligosaccharides. Furthermore, partial occupancy of two consecutive xylose residues at subsites ‐2 and ‐1 suggests an alternative binding mode for XOS in the vicinity of the catalytic center. Interestingly, the ‐1 xylosyl unit exhibits an open aldehyde conformation in one of the structures and a ring‐closed pyranoside in another complex. Complementary inhibition studies with <italic>p</italic>‐nitrophenyl lactoside as substrate indicate mixed inhibition rather than pure competitive inhibition.</p> </sec> <sec id="febs13265-sec-0002" sec-type="section"> <title>Database</title> <p>The atomic coordinates and structure factors are available in the Protein Data Bank under accession number <ext-link ext-link-type="uri" xlink:href="http://www.rcsb.org/pdb/search/structidSearch.do?structureId=4D5I" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink">4D5I</ext-link> (<italic>H. jecorina</italic> Cel7A E212Q variant, complex with xylotriose), <ext-link ext-link-type="uri" xlink:href="http://www.rcsb.org/pdb/search/structidSearch.do?structureId=4D5J" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink">4D5J</ext-link> (<italic>H. jecorina</italic> Cel7A E217Q variant, complex with xylotriose), <ext-link ext-link-type="uri" xlink:href="http://www.rcsb.org/pdb/search/structidSearch.do?structureId=4D5O" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink">4D5O</ext-link> (<italic>H. jecorina</italic> Cel7A E212Q variant, complex with xylopentaose), <ext-link ext-link-type="uri" xlink:href="http://www.rcsb.org/pdb/search/structidSearch.do?structureId=4D5P" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink">4D5P</ext-link> (<italic>H. jecorina</italic> Cel7A E217Q variant, complex with xylopentaose), <ext-link ext-link-type="uri" xlink:href="http://www.rcsb.org/pdb/search/structidSearch.do?structureId=4D5Q" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink">4D5Q</ext-link> (wild‐type <italic>H. jecorina</italic> Cel7A, complex with xylopentaose) and <ext-link ext-link-type="uri" xlink:href="http://www.rcsb.org/pdb/search/structidSearch.do?structureId=4D5V" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink">4D5V</ext-link> (<italic>H. jecorina</italic> Cel7A E217Q variant, complex with xylotetraose).</p> </sec> </abstract>