The genes for three xylan-degrading activities from Bacteroides ovatus are clustered in a 3.8-kilobase region

Abstract

Genes coding for three xylan-degrading activities, xylanase, xylosidase, and arabinosidase, were simultaneously cloned from the colonic anaerobic organism Bacteriodes ovatus. The genes for the three enzymes were located on a 3.8-kilobase EcoRI genomic insert and were cloned by using plasmid pUC18. All three activities were expressed in Escherichia coli JM83, and all were cell associated. Expression of the xylanase gene was independent from expression of the xylosidase and arabinosidase genes, whereas expression of the latter two genes appeared to be coordinated. Restriction endonuclease analysis of the arabinosidase and xylosidase genes and partial purification of these enzyme activities from E. coli suggested that these activities were catalyzed by a bifunctional protein or two proteins of very similar molecular weight. All three enzyme activities were regulated in B. ovatus in response to the carbon source used for growth. This is the first report of the cloning and expression of B. ovatus genes.

A unique eukaryotic β-xylosidase gene from the phytopathogenic fungus Cochliobolus carbonum

“…Xypl is related in both size and primary sequence to two bacterial P-xylosidases, those of Bacteroides ouatus (35 70 overall identity) and Preuotella (formerly Bacteroides) ruminicola (30 YO identity) (Whitehead & Hespell, 1990;Whitehead, 1995 ;Gasparic et al, 1995) (Fig. 2).…”

Cloning and Sequencing of thexynCGene Encoding Acid Xylanase ofAspergillus kawachii

“…Xylanolytic microorganisms often produce multiple xylanases, which can be derived either from the processing of a single gene productl) or from the direct product of multiple xylanase genes. 2 ) Aspergillus kawachii is a common fungus used in the fermentation of shochu (Japanese traditional spirit), and this strain makes a large quantity of citric acid and simultaneously produces many interesting acid stable enzymes including several xylanases and cellulases, among which we have purified three xylanases and characterized their properties. 3) We are now cloning the gcnes encoding these xylanases and studying the structures of the genes and proteins, from which we have reported the cloning of the xynA gene encoding xylanase A of A. kawachii.…”

Novel xylan-controlled delivery of therapeutic proteins to inflamed colon by the human anaerobic commensal bacterium

“…The Bacteroides are dominant among commensal anaerobes and have been identified in the mucin layer coating the colonic mucosa, 14 making them ideal for therapeutic protein delivery directly to the injured epithelium. The ability of B ovatus to use xylan as its sole energy source 15,16 and the inability of the human gut to digest xylan 17 probably contributes to their predominance in the colonic microbiota. It is likely that BO-KGF and BO-TGF delivers growth factors directly to the epithelium via diffusion or by receptors expressed on the basolateral surface of epithelial cells 18,19 made accessible as a result of compromised barrier function in the inflamed colon.…”