CLONING AND NUCLEOTIDE-SEQUENCE OF THE BUTYRIVIBRIO-FIBRISOLVENS GENEENCODING A TYPE-III GLUTAMINE-SYNTHETASE

A Butyrivihrio fibrisolvens glnA gene encoding glutamine synthetase (G S) was cloned on a recombinant plasmid pGS4 which enabled Escherichia coli glnA deletion mutants to utilize (NH4)2SO4 as a sole source of ni trogen. The nucleotide sequence of a 2423 bp DNA segment containing th e GS-coding region of B.fibrisolvens was determined and the complete a mino acid sequence (701 residues) was deduced. Comparisons of the deri ved B.fibrisolvens GS protein sequence with the amino acid sequences o f GS from other bacteria indicate that it is the second reported examp le of a type III GS, originally identified in the obligate anaerobe Ba cteroides fragilis. The presence of GS in B. fibrisolvens cells and th e regulation of the cloned GS in E. coli cells was demonstrated by Wes tern blot analysis.