FIG. 4.

Phenotype of a virB8 mutant. The effect of alteration of VirB8 serine 87 to leucine on DNA transfer was monitored by complementation assays (A). Agrobacterium sp. strain A348ΔB8 (ΔB8) harboring plasmid pAD1433 containing wild-type (wt) virB8 or its derivative pAD1433S87L containing virB8S87L (S87L) was used to infect Kalanchöe leaves. Tumor formation was monitored 3 weeks after infection. A348, Agrobacterium sp. strain A348 that harbors the octopine Ti-plasmid pTiA6. (B) Interaction of VirB8S87L with VirB8, VirB9, and VirB10 was studied by the yeast two-hybrid assays. A blue colony color phenotype indicates a positive interaction. Row 1, VirB8; row 2, VirB8S87L.