CONTRIBUTION OF THE 65-KILODALTON PROTEIN ENCODED BY THE CLONED GENE CRY19A TO THE MOSQUITOCIDAL ACTIVITY OF BACILLUS-THURINGIENSIS SUBSP JEGATHESAN

Two new crystal protein genes, cry19A and orf2, isolated from Bacillus thuringiensis subsp, jegathesan were cloned and characterized. The cr y19A gene encodes a 74.7-kDa protein, and the orf2 gene encodes a 60-k Da protein, Cry19A contains the five conserved blocks present in most B. thuringiensis delta-endotoxins. The ORF2 amino acid sequence is sim ilar to that of the carboxy terminus of Cry4 proteins, The cry19A gene was expressed independently or in combination with orf2 in a crystal- negative B. thuringiensis host, The proteins accumulated as inclusions . Purified inclusions containing either Cry19A alone or Cry19A and ORF 2 together were toxic to Anopheles stephensi and Culex pipiens mosquit o larvae, They were more toxic to C. pipiens than to A, stephensi, How ever, inclusions containing Cry19A and ORF2 together were more toxic t han inclusions of Cry19A alone but less toxic than the wild-type inclu sions of B. thuringiensis subsp. jegathesan.