Polysaccharide utilization loci from Bacteroidota encode CE15 enzymes with possible roles in cleaving pectin-lignin bonds
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Polysaccharide utilization loci from Bacteroidota encode CE15 enzymes with possible roles in cleaving pectin-lignin bonds. / Seveso, Andrea; Mazurkewich, Scott; Banerjee, Sanchari; Poulsen, Jens-christian Navarro; Lo Leggio, Leila; Larsbrink, Johan.
I: Applied and Environmental Microbiology, Bind 90, Nr. 1, 2024.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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T1 - Polysaccharide utilization loci from Bacteroidota encode CE15 enzymes with possible roles in cleaving pectin-lignin bonds
AU - Seveso, Andrea
AU - Mazurkewich, Scott
AU - Banerjee, Sanchari
AU - Poulsen, Jens-christian Navarro
AU - Lo Leggio, Leila
AU - Larsbrink, Johan
PY - 2024
Y1 - 2024
N2 - Lignocellulose is a renewable but complex material exhibiting high recalcitrance to enzymatic hydrolysis, which is attributed, in part, to the presence of covalent linkages between lignin and polysaccharides in the plant cell wall. Glucuronoyl esterases from carbohydrate esterase family 15 (CE15) have been proposed as an aid in reducing this recalcitrance by cleaving ester bonds found between lignin and glucuronoxylan. In the Bacteroidota phylum, some species organize genes related to carbohydrate metabolism in polysaccharide utilization loci (PULs) which encode all necessary proteins to bind, deconstruct, and respond to a target glycan. Bioinformatic analyses identified CE15 members in some PULs that appear to not target the expected glucuronoxylan. Here, five CE15 members from such PULs were investigated with the aim of gaining insights on their biological roles. The selected targets were characterized using glucuronoyl esterase model substrates and with a new synthetic molecule mimicking a putative ester linkage between pectin and lignin. The CE15 enzyme from Phocaeicola vulgatus was structurally determined by X-ray crystallography both with and without carbohydrate ligands with galacturonate binding in a distinct conformation than that of glucuronate. We further explored whether these CE15 enzymes could act akin to pectin methylesterases on pectin-rich biomass but did not find evidence to support the proposed activity. Based on the evidence gathered, the CE15 enzymes in the PULs expected to degrade pectin could be involved in cleavage of uronic acid esters in rhamnogalacturonans.
AB - Lignocellulose is a renewable but complex material exhibiting high recalcitrance to enzymatic hydrolysis, which is attributed, in part, to the presence of covalent linkages between lignin and polysaccharides in the plant cell wall. Glucuronoyl esterases from carbohydrate esterase family 15 (CE15) have been proposed as an aid in reducing this recalcitrance by cleaving ester bonds found between lignin and glucuronoxylan. In the Bacteroidota phylum, some species organize genes related to carbohydrate metabolism in polysaccharide utilization loci (PULs) which encode all necessary proteins to bind, deconstruct, and respond to a target glycan. Bioinformatic analyses identified CE15 members in some PULs that appear to not target the expected glucuronoxylan. Here, five CE15 members from such PULs were investigated with the aim of gaining insights on their biological roles. The selected targets were characterized using glucuronoyl esterase model substrates and with a new synthetic molecule mimicking a putative ester linkage between pectin and lignin. The CE15 enzyme from Phocaeicola vulgatus was structurally determined by X-ray crystallography both with and without carbohydrate ligands with galacturonate binding in a distinct conformation than that of glucuronate. We further explored whether these CE15 enzymes could act akin to pectin methylesterases on pectin-rich biomass but did not find evidence to support the proposed activity. Based on the evidence gathered, the CE15 enzymes in the PULs expected to degrade pectin could be involved in cleavage of uronic acid esters in rhamnogalacturonans.
U2 - 10.1128/aem.01768-23
DO - 10.1128/aem.01768-23
M3 - Journal article
C2 - 38179933
VL - 90
JO - Applied and Environmental Microbiology
JF - Applied and Environmental Microbiology
SN - 0099-2240
IS - 1
ER -
ID: 379585661