REVISION OF THE NOMENCLATURE FOR THE BACILLUS-THURINGIENSIS PESTICIDAL CRYSTAL PROTEINS

The crystal proteins of Bacillus thuringiensis have been extensively s tudied because of their pesticidal properties and their high natural l evels of production. The increasingly rapid characterization of new cr ystal protein genes, triggered by an effort to discover proteins with new pesticidal properties, has resulted in a variety of sequences and activities that no longer,fit the original nomenclature system propose d tn 1989. Bacillus thuringiensis pesticidal crystal protein (Cly and Cyt) nomenclature was initially based on insecticidal activity for the primary ranking criterion. Many exceptions to this systematic arrange ment have become apparent, however; making the nomenclature system inc onsistent. Additionally, the original nomenclature, with foul activity -based primary ranks for 13 genes, did not anticipate the current 73 h olotype sequences that form many more than the original four subgroups . A new nomenclature, based on hierarchical clustering using amino aci d sequence identity, is proposed. Roman numeral have been exchanged fo r Arabic numerals in the primary rank (e.g., Cry1Aa) to better accommo date the large number of expected new sequences. In this proposal, 133 crystal proteins comprising 24 primary ranks are systematically arran ged.