Dataset Information

The membrane lipoprotein LppX of Paenibacillus sp. strain W-61 serves as a molecular chaperone for xylanase of glycoside hydrolase family 11 during secretion across the cytoplasmic membrane.

ABSTRACT: Paenibacillus sp. strain W-61, which can utilize xylan as the sole source of carbon and energy, produces extracellular xylanases 1 and 3 (Xyn1 and Xyn3) and cell surface xylanase 5. In this study we found that lppX, immediately downstream of xyn1, encodes a lipoprotein located on the outer layer of the cytoplasmic membrane and that the LppX lipoprotein is essential for the secretion of active Xyn1 across the cytoplasmic membranes. In Escherichia coli, wild-type LppX was destined for the inner layer of the outer membrane. Mutant LppX(C19A), in which Cys-19, a possible lipomodification residue, is replaced with Ala, was located in the periplasm without being anchored to the membranes. Another mutant, LppX(S20D S21D), with substitutions of Asp for Ser-20 and Ser-21 (conversion to an Asp-Asp signal for sorting to the inner membrane), resided on the outer layer of the inner membrane, demonstrating that LppX has the sorting property of a lipoprotein. E. coli harboring both xyn1 and lppX secreted active Xyn1 into the periplasm. In contrast, E. coli carrying xyn1 alone failed to do so, accumulating inactive Xyn1 in the cytoplasmic membranes. Exogenous LppX(C19A) liberated the inactive Xyn1, which had been stagnating in the inner membrane, into the medium as an active enzyme. Thus, we propose that LppX is a novel type of lipoprotein that assists Xyn1 in making the proper fold necessary for traveling across the cytoplasmic membranes to be secreted as an active enzyme.

SUBMITTER: Fukuda M

PROVIDER: S-EPMC2648208 | biostudies-literature | 2009 Mar

REPOSITORIES: biostudies-literature

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The membrane lipoprotein LppX of Paenibacillus sp. strain W-61 serves as a molecular chaperone for xylanase of glycoside hydrolase family 11 during secretion across the cytoplasmic membrane.

Fukuda Mutsumi M Watanabe Seiji S Kaneko Jun J Itoh Yoshifumi Y Kamio Yoshiyuki Y

Journal of bacteriology 20081219 5

Paenibacillus sp. strain W-61, which can utilize xylan as the sole source of carbon and energy, produces extracellular xylanases 1 and 3 (Xyn1 and Xyn3) and cell surface xylanase 5. In this study we found that lppX, immediately downstream of xyn1, encodes a lipoprotein located on the outer layer of the cytoplasmic membrane and that the LppX lipoprotein is essential for the secretion of active Xyn1 across the cytoplasmic membranes. In Escherichia coli, wild-type LppX was destined for the inner la ...[more]

PMID: 19103919

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Project description:UnlabelledA GH8 family enzyme involved in xylan depolymerization has been characterized. The enzyme, Rex8A, is a reducing-end xylose-releasing exo-oligoxylanase (Rex) that efficiently hydrolyzes xylooligosaccharides and shows minor activity on polymeric xylan. Rex8A hydrolyzes xylooligomers of 3 to 6 xylose units to xylose and xylobiose in long-term incubations. Kinetic constants of Rex8A were determined on xylotriose, showing a Km of 1.64 ± 0.03 mM and a kcat value of 118.8 s(-1) Besides linear xylooligosaccharides, the enzyme hydrolyzed decorated xylooligomers. The catalytic activity on branched xylooligosaccharides, i.e., the release of xylose from the reducing end, is a newly described trait of xylose-releasing exo-oligoxylanases, as the exo-activity on these substrates has not been reported for the few of these enzymes characterized to date. Modeling of the three-dimensional (3D) structure of Rex8A shows an (α/α)6 barrel fold where the loops connecting the α-helices contour the active site. These loops, which show high sequence diversity among GH8 enzymes, shape a catalytic cleft with a -2 subsite that can accommodate methyl-glucuronic acid decorations. The hydrolytic ability of Rex8A on branched oligomers can be crucial for the complete depolymerization of highly substituted xylans, which is indispensable to accomplish biomass deconstruction and to generate efficient catalysts.ImportanceA GH8 family enzyme involved in xylan depolymerization has been characterized. The Rex8A enzyme from Paenibacillus barcinonensis is involved in depolymerization of glucuronoxylan, a major component of the lignocellulosic substrates. The study shows that Rex8A is a reducing-end xylose-releasing exo-oligoxylanase that efficiently hydrolyzes xylose from neutral and acidic xylooligosaccharides generated by the action of other xylanases also secreted by the strain. The activity of a Rex enzyme on branched xylooligosaccharides has not been described to date. This report provides original and useful information on the properties of a new example of the rarely studied Rex enzymes. Depolymerization of highly substituted xylans is crucial for biomass valorization as a platform for generation of biofuels, chemicals, and solvents.

Dataset Information

The membrane lipoprotein LppX of Paenibacillus sp. strain W-61 serves as a molecular chaperone for xylanase of glycoside hydrolase family 11 during secretion across the cytoplasmic membrane.

Publications

The membrane lipoprotein LppX of Paenibacillus sp. strain W-61 serves as a molecular chaperone for xylanase of glycoside hydrolase family 11 during secretion across the cytoplasmic membrane.

Similar Datasets

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