MOLECULAR-CLONING, STRUCTURAL-ANALYSIS, AND EXPRESSION IN ESCHERICHIA-COLI OF A CHITINASE GENE FROM ENTEROBACTER-AGGLOMERANS

The gene chiA, which codes for endochitinase, was cloned from a soilbo rne Enterobacter agglomerans, Its complete sequence was determined, an d the deduced amino acid sequence of the enzyme designated Chia_Entag yielded an open reading frame coding for 562 amino acids of a 61-kDa p recursor protein with a putative leader peptide at its N terminus. The nucleotide and polypeptide sequences of Chia_Entag showed 86.8 and 87 .7% identity with the corresponding gene and enzyme, Chia_Serma, of Se rratia marcescens, respectively, Homology modeling of Chia_Entag's thr ee-dimensional structure demonstrated that most amino acid substitutio ns are at solvent-accessible sites, Escherichia coli JM109 carrying th e E. agglomerans chili gene produced and secreted Chia_Entag, The anti fungal activity of the secreted endochitinase was demonstrated in vitr o by inhibition of Fusarium oxysporum spore germination. The transform ed strain inhibited Rhizoctonia solani growth on plates and the root r ot disease caused by this fungus in cotton seedlings under greenhouse conditions.