Cloning and characterization of the bgxA gene from Erwinia chrysanthemi D1 which encodes a beta-glucosidase/xylosidase enzyme
1995
Vroemen, S. | Heldens, J. | Boyd, C. | Henrissat, B. | Keen, N.T. (California Univ., Riverside (USA). Dept. of Plant Pathology and Genetics Graduate Group)
A beta-glucosidase/xylosidase gene from Erwinia chrysanthemi strain D1 was cloned and sequenced. This gene, named bgxA, encodes a ca. 71 kDa protein product which, following removal of the leader peptide, resulted in a ca. 69 kDa mature protein that accumulated in the periplasmic space of E. chrysanthemi strain D1 and Escherichia coli cells expressing the cloned gene. The protein exhibited both beta-glucosidase and beta-xylosidase activities but gave no detectable activity on xylan or carboxymethyl cellulose. The enzyme was classified as a type 3 glycosyl hydrolase, but was unusual in having a truncated B region at the carboxyl-terminus. Several E. chrysanthemi strains isolated from corn produced the glucosidase/xylosidase activity but not those isolated from dicot plants. However, bgxA marker exchange mutants of strain D1 were not detectably altered in virulence on corn leaves.
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