cover illustration Vegetative insecticidal protein,Vip2, is a Bacillus ADP-ribosyltransferase that modifies actin, preventing polymerization. Expression of Vip2 in eukaryotic systems (e.g. plants or yeast) is lethal. An enzymatic precursor, proVip2, which would silently reside in one biological system (e.g. plants or yeast) and be activated in another (insect larvae) was designed. The approach involved engineering a C-terminal random propeptide library and selecting for malfunctional enzyme variants of Vip2 in yeast. The image represents the Vip2-NAD complex and one hypothesized effect of the additional propeptide sequence extension. (A) NAD molecule bound in a cleft within the C-terminal enzymatic domain of Vip2 (B) C-terminal polypeptide chain present in proVip2 (in yellow) interfering with the NAD binding site. For further details please see Jucovic et al., pp. 631-638.
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