Subcellular distribution of glycanases and related components in Ruminococcus albus SY3 and their role in cell adhesion to cellulose

Authors


Miron Metabolic Unit, Agricultural Research Organization, The Volcani Center, P.O.Box 6 Bet Dagan, 50250 Israel (e-mail: jmiron@actcom.co.il).

Abstract

Aims: To compare the subcellular distribution of glycanase-related components between wild-type Ruminococcus albus SY3 and an adhesion-defective mutant, to identify their possible contribution to the adhesion process, and to determine their association with cellulosome-like complexes.

Methods and Results: Cell fractionation revealed that most of the cellulases and xylanases were associated with capsular and cell-wall fractions. SDS-PAGE and gel filtration indicated that most of the bacterial enzyme activity was not integrated into cellulosome-like complexes. The adhesion-defective mutant produced significantly less (5- to 10-fold) overall glycanase activity, and the ‘true cellulase activity’ appeared to be entirely confined to the cell membrane fractions. Antibodies specific for the cellulosomal scaffoldin of Clostridium thermocellum recognized a single 240 kDa band in R. albus SY3.

Conclusions: The adhesion-defective mutant appeared to be blocked in exocellular transport of enzymes involved in true cellulase activity. A potential cellulosomal scaffoldin candidate was identified in R. albus SY3.

Significance and Impact of the Study: Several glycanase-related proteins and more than one mechanism appear to be involved in the adhesion of R. albus SY3 to cellulose.

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