Genome Sequence of the Cellulolytic Gliding Bacterium Cytophaga hutchinsonii

Abstract

The complete DNA sequence of the aerobic cellulolytic soil bacterium Cytophaga hutchinsonii, which belongs to the phylum Bacteroidetes, is presented. The genome consists of a single, circular, 4.43-Mb chromosome containing 3,790 open reading frames, 1,986 of which have been assigned a tentative function. Two of the most striking characteristics of C. hutchinsonii are its rapid gliding motility over surfaces and its contact-dependent digestion of crystalline cellulose. The mechanism of C. hutchinsonii motility is not known, but its genome contains homologs for each of the gld genes that are required for gliding of the distantly related bacteroidete Flavobacterium johnsoniae. Cytophaga-Flavobacterium gliding appears to be novel and does not involve well-studied motility organelles such as flagella or type IV pili. Many genes thought to encode proteins involved in cellulose utilization were identified. These include candidate endo-␤-1,4-glucanases and ␤-glucosidases. Surprisingly, obvious homologs of known cellobiohydrolases were not detected. Since such enzymes are needed for efficient cellulose digestion by well-studied cellulolytic bacteria, C. hutchinsonii either has novel cellobiohydrolases or has an unusual method of cellulose utilization. Genes encoding proteins with cohesin domains, which are characteristic of cellulosomes, were absent, but many proteins predicted to be involved in polysaccharide utilization had putative D5 domains, which are thought to be involved in anchoring proteins to the cell surface.

Genome, transcriptome, and secretome analysis of wood decay fungus Postia placenta supports unique mechanisms of lignocellulose conversion

“…Among aerobes, only the cellulolytic gliding bacterium Cytophaga hutchinsonii lacks exocellobiohydrolases and endoglucanases fused to cellulose-binding domains (22). The precise mechanism used by C. hutchinsonii is somewhat mysterious, but it has been suggested that cellulose chains are peeled away from the polymer and transported into the periplasm (23).…”

Cel9D, an Atypical 1,4-β- d -Glucan Glucohydrolase from Fibrobacter succinogenes : Characteristics, Catalytic Residues, and Synergistic Interactions with Other Cellulases

“…A putative protein that has 37% sequence identity to Cel9D was identified from the genome of a phylogenetically related bacterium, Cytophaga hutchinsonii (35). Cellulase systems of F. succinogenes and C. hutchinsonii are quite similar and distinct from other cellulolytic bacteria in that both bacteria lack genes encoding proteins with similarity to members from GH6 or GH48; most cellulases in both bacteria are cell associated but lack a carbohydrate binding module, and no cellulosome structures were identified (21,35).…”

A protein secretion system linked to bacteroidete gliding motility and pathogenesis

“…PorT is required for P. gingivalis gingipain secretion, and may interact with other proteins to form the translocation machinery. porT homologs are found in some other members of the phylum Bacteroidetes, such as C. hutchinsonii ATCC 33406, but not in others, such as B. thetaiotaomicron VPI-5482 (13)(14)(15). To identify possible additional components of the gingipain secretion system, we identified 55 genes in addition to porT that were present in P. gingivalis and C. hutchinsonii but absent in B. thetaiotaomicron ( Fig.…”