Cellular location of enzymes involved in chondroitin sulfate breakdown by Bacteroides thetaiotaomicron

Salyers, Abigail A.; O'Brien, M.

doi:10.1128/jb.143.2.772-780.1980

Cited by 126 publications

(69 citation statements)

References 26 publications

(20 reference statements)

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“…A recent study of enzymes involved in the breakdown of the mucopolysaccharide chondroitin sulfate by Bacteroides thetaiotaomicron has shown that the first degradative enzyme is in the periplasmic space (A. Salyers and O'Brien 1980). Solubility or hydration state of the xylan appears to be an important factor in enzymic hydrolysis.…”

Section: Discussionmentioning

confidence: 99%

Breakdown of Xylan by Enzymes From Human Colonic Bacteria

Salyers

Balascio

Palmer

1982

J Food Biochemistry

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Xylan from Larchwood was utilized as a carbon source by three species of Bacteroides from the human colon: Bacteroides ovatus, Bacteroides eggerthii and Bacteroides fragilis subsp. a. Xylan‐degrading enzymes of all three species were cell‐associated rather than extracellular, i.e. xylanase activity was detected in sonically disrupted bacteria but not in the extracellular fluid. The state of hydration of the xylan was an important factor in determining the extent to which the xylan was hydrolyzed by the bacterial enzymes. When xylan which had been partially hydrated by autoclaving was subjected to centrifugation at 17,000 xg for 20 min at 40C, a portion of the xylan was pelleted. This portion, which was presumably less well hydrated than the xylan which remained in solution, was not digested at all by the bacterial enzymes. By contrast, xylan which remained soluble after centrifugation (soluble xylan) was degraded by bacterial xylanases. Xylose was the main product of digestion, although traces of arabinose, glucose and higher oligomers of xylose were also detected. Even after exhaustive hydrolysis, less than 60% of the soluble xylan was hydrolyzed. Removal of most of the arabinose branches did not increase the extent of hydrolysis. Moreover, the carbohydrate composition of the portion of the soluble xylan which resisted hydrolysis was the same as the composition of the xylan which was hydrolyzed. Thus it is likely that hydrolysis was limited by aggregate formation rather than by structural features such as arabinose branches.

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Section: Discussionmentioning

confidence: 99%

Breakdown of Xylan by Enzymes From Human Colonic Bacteria

Salyers

Balascio

Palmer

1982

J Food Biochemistry

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“…Two arguments speak against this hypothesis. First, the B. thetaiotaomicron chondroitin sulfatases have been shown to be intracellular [181], and all the Ser-type sulfatases identi¢ed to date carry a signal sequence for export to the periplasm. Secondly, the changes in protein expression observed by 2D-PAGE in the chuR mutant are inconsistent with a role of ChuR solely as a modifying protein, though such an e¡ect could be caused by decreased stability of the target proteins if they remain unmodi¢ed (as has been observed for the C51A mutant of P. aeruginosa arylsulfatase [13]).…”

Section: Carbohydrate Sulfatasesmentioning

confidence: 99%

Riding the sulfur cycle – metabolism of sulfonates and sulfate esters in Gram-negative bacteria

2000

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Sulfonates and sulfate esters are widespread in nature, and make up over 95% of the sulfur content of most aerobic soils. Many microorganisms can use sulfonates and sulfate esters as a source of sulfur for growth, even when they are unable to metabolize the carbon skeleton of the compounds. In these organisms, expression of sulfatases and sulfonatases is repressed in the presence of sulfate, in a process mediated by the LysR-type regulator protein CysB, and the corresponding genes therefore constitute an extension of the cys regulon. Additional regulator proteins required for sulfonate desulfonation have been identified in Escherichia coli (the Cbl protein) and Pseudomonas putida (the AsfR protein). Desulfonation of aromatic and aliphatic sulfonates as sulfur sources by aerobic bacteria is oxygendependent, carried out by the K-ketoglutarate-dependent taurine dioxygenase, or by one of several FMNH 2 -dependent monooxygenases. Desulfurization of condensed thiophenes is also FMNH 2 -dependent, both in the rhodococci and in two Gram-negative species. Bacterial utilization of aromatic sulfate esters is catalyzed by arylsulfatases, most of which are related to human lysosomal sulfatases and contain an active-site formylglycine group that is generated post-translationally. Sulfate-regulated alkylsulfatases, by contrast, are less well characterized. Our increasing knowledge of the sulfur-regulated metabolism of organosulfur compounds suggests applications in practical fields such as biodesulfurization, bioremediation, and optimization of crop sulfur nutrition. ß

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“…The fate of sulphate groups was not investigated in any of the studies cited above. Because desulphation of other sulphated substrates (mucin, chondroitin sulphate) has been shown to occur after depolymerization, through the activities of bacterial cytoplasmic enzymes (Salyers and O'Brien 1980;Wilkinson and Robertson 1988), fucans are likely to retain their sulphate groups during transit of the colon, thereby manifesting high cationic exchange capacities throughout the digestive tract. This would be of nutritional and physiological significance due to the occurrence of ionic exchange reactions, an example being the binding of bile salts.…”

Section: Fucansmentioning

confidence: 99%