Mechanisms involved in xyloglucan catabolism by the cellulosome-producing bacterium Ruminiclostridium cellulolyticum

Abstract

Xyloglucan, a ubiquitous highly branched plant polysaccharide, was found to be rapidly degraded and metabolized by the cellulosome-producing bacterium Ruminiclostridium cellulolyticum. Our study shows that at least four cellulosomal enzymes displaying either endo- or exoxyloglucanase activities, achieve the extracellular degradation of xyloglucan into 4-glucosyl backbone xyloglucan oligosaccharides. The released oligosaccharides (composed of up to 9 monosaccharides) are subsequently imported by a highly specific ATP-binding cassette transporter (ABC-transporter), the expression of the corresponding genes being strongly induced by xyloglucan. This polysaccharide also triggers the synthesis of cytoplasmic β-galactosidase, α-xylosidase, and β-glucosidase that act sequentially to convert the imported oligosaccharides into galactose, xylose, glucose and unexpectedly cellobiose. Thus R. cellulolyticum has developed an energy-saving strategy to metabolize this hemicellulosic polysaccharide that relies on the action of the extracellular cellulosomes, a highly specialized ABC-transporter, and cytoplasmic enzymes acting in a specific order. This strategy appears to be widespread among cellulosome-producing mesophilic bacteria which display highly similar gene clusters encoding the cytosolic enzymes and the ABC-transporter.

Phellinus linteus polysaccharide extract improves insulin resistance by regulating gut microbiota composition

“…12,42 Abundance of butyrate-producing Blautia was correlated with high-carbohydrate content. In the present study, the PLPE group showed reduced levels of LPS-producing Escherichia-Shigella, 11 necrotic enteritis-related Clostridium_sensu_stricto_1, 47 conditionally pathogenic Bacteroidales_S24-7_group, 43 and intestinal mucin-degraded Akkermansia. 46 Low levels of SCFA-producing bacteria in diabetic rats are enhanced by PLPE treatment.…”

“…41 Dietary polysaccharides increased the abundance in intestinal tract of Prevotella, a type of succinate-producing bacteria. 34 Other bacteria potentially able to break down polysaccharides to produce SCFAs include Ruminiclostridium-9, 43 Eubacterium_xylanophilum, 44 Anaerotruncus, 45 and Oscillibacter. 12,42 Abundance of butyrate-producing Blautia was correlated with high-carbohydrate content.…”

Whole Proteome Analyses on Ruminiclostridium cellulolyticum Show a Modulation of the Cellulolysis Machinery in Response to Cellulosic Materials with Subtle Differences in Chemical and Structural Properties

“…Indeed, cellulosomal proteins encoded by the “ xyl-doc” cluster (14 genes more specifically oriented towards hemicellulolysis [16]) did not show any significant differences, although 8 of them were quantified in the whole dataset (S1 Dataset). The cellulosomal endoglucanase Ccel_0429, presenting higher levels in Tissue incubations, could have participated to hemicellulose deconstruction since it exerts xyloglucan depolymerization as a secondary activity [39]; however its regulation mechanisms are unknown. Finally, the other cellulosomal subunits with a known xylanase activity and statistically significant differences had lower levels in Tissue incubations (Ccel_0755 in Table 2, Ccel_0931 in Table 3).…”

Gut microbiota determines the prevention effects of Luffa cylindrica (L.) Roem supplementation against obesity and associated metabolic disorders induced by high‐fat diet

“…1F and Supplemental Fig. S1G), which may be associated with cellulose degradation (50); specific mechanisms still need to be investigated in the future. Additionally, we still found that LC also selectively increased the sulfatereducing bacteria Desulfovibrio ( Fig.…”