Skip to main content
ARS Home » Research » Publications at this Location » Publication #105318
Title: GENE STRUCTURE OF A BIFUNCTIONAL CELLULASE GENE (CELA) ISOLATED FROM TEREDINOBACTER TURNERAE

Author
item Freer, Shelby
item Greene, Richard
item Bothast, Rodney

Submitted to: American Chemical Society Symposium Series
Publication Type: Book / Chapter
Publication Acceptance Date: 10/26/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Cellulose is the most abundant plant polymer on earth and, as such, has the potential to serve as a renewable carbon/energy source for the fermentative production of chemicals, such as fuel alcohol. However, before yeast can ferment cellulose, the polymer must first be broken down into its component sugars, glucose, and/or cellobiose. Biologically, this is achieved by the action of two different enzymes, endocellulase and exocellulase. In the vast majority of cellulases studied, these proteins contain a single active domain. Thus, if the utilizable carbon source of an organism is to be expanded, two separate genes must be cloned and expressed in the foreign host. We have cloned a unique gene from a marine shipworm bacterium. The cellulase gene that we have isolated and characterized contains both an exocellulase and an endocellulase. If high expression levels of this gene can be achieved in a foreign host, the recombinant organism should be able to grow/ferment cellulose after the introduction of only a single gene.

Technical Abstract: Bacterial cultures (Teredinobacter turnerae) isolated from the gland of Deshayes of the marine shipworm (Psiloteredo healdi) produce extracellular cellulase activity when cultured with cellulose. Screening a pUC 19 genomic DNA library for clearing of Ostrazin Brilliant Red-hydroxyethyl cellulose allowed for isolation of the T. turnerae celA gene. Sequence analysis revealed that the celA gene encodes a putative protein of 1010 amino acids (106.068 kDa). The protein appears to be multidomained, consisting of a N-terminal endocellulase, two cellulose-binding domains, and a C-terminal exocellulase. Three linker regions, rich in serine, separate the four distinct activity domains. The endocellulase domain is most closely related to celE of P. fluorescens, while the exocellulase domain is most closely related to the cbhA gene of Cellulomonas fimi.