[Construction and analysis of transgenic plants of Nicotiana tabacum L. expressing a bacterial gene for beta-1,3-glucanase. I. Construction of vector plasmids for transfer into plants and expression of a modified gene for beta-1,3-glucanase from Clostridium thermocellum in tobacco protoplasts].

We constructed two vectors, pC27-glc and pC29-glc, that allow expression of the beta-1,3-glucanase gene (glc) in plant cells. The glc gene was previously cloned from anaerobic thermophilous bacterium Clostridium thermocellum. To increase the efficiency of expression, the N-terminal fragment of the glc gene encoding bacterial transient peptide was deleted, and hybrid variants of lacZ-glc were obtained. Analysis of expression of the hybrid genes in Escherichia coli showed that deletion of the fragment corresponding to 31 amino acids (a.a.) of beta-glucanase affected neither activity nor thermostability of the enzyme. The modified gene was subcloned into two vectors, pC27 and pC29, in which its expression was controlled by the TR2' promoter of the 2' gene of T-DNA and the rbcS promoter from Arabidopsis, respectively. Each of the resulting plasmids, pC27-glc and pC29-glc, was transfected into protoplasts of Nicotiana plumbaginifolia. Both the plasmids were shown to allow a high level of activity of the thermostable beta-1,3-glucanase. We plan to use the vectors obtained for transformation of agrobacteria and construction of transgenic plants.