Sequence of egV and properties of EgV, a Ruminococcus albus endoglucanase containing a dockerin domain

The Ruminococcus albus F-40 egV gene, encoding endoglucanase V (EGV), consi sts of an open reading frame of 1,833 nucleotides and encodes 611 amino aci ds with a deduced molecular weight of 67,103. The deduced EGV isa modular e nzyme composed of a catalytic domain of family 5 of glycosyl hydrolases, a domain of unknown function, and a dockerin domain responsible for celluloso me assembly, suggesting that R. albus F-40 produces a cellulosome, and EGV is a component of the cellulosome. A truncated form of EGV with an apparent molecular weight of 42,000 was purified from a recombinant Escherichia coi l and characterized since EGV suffered from partial proteolysis by E. coli protease(s). The truncated EGV was active toward carboxylmethyl cellulose, xylan, lichenan, and acid-swollen cellulose. The pH and temperature optima of the enzyme were 7.0 and 40 degrees C, respectively. By Western blot anal ysis using the antiserum raised against the truncated enzyme, EGV was detec ted in the whole cells but not in the culture supernatant of R, alubus F-40 , suggesting that EGV was located on the cell surface.