TABLE 2.

Effects of i4 insertions on substrate transfer and pilus production

StrainaVirulencebTransfer of:Exocellular VirB2f
T-DNAcVirE2dpML122ΔKme
A348+++ (++)NANA1.5 × 10−4+++ (+)
PC1006 (ΔB6)<1 × 10−8
Plac-virB6+++ (++)NANA6.8 × 10−5+++ (+)
PvirB-virB6+++ (−)NANA1.7 × 10−4+++ (+)
E29<1 × 10−8
D60<1 × 10−8
Q85<1 × 10−8
T114<1 × 10−8
Q140++1.2 × 10−5
L165<1 × 10−8
L191++9.8 × 10−6
F225<1 × 10−8
I250<1 × 10−8
A280+++ (−)NANA5.8 × 10−5+++ (+)
  • a PC1006 strains expressed native virB6 from the Plac or PvirB promoter or virB6.i4 alleles from PvirB.

  • b Monitored by tumor formation at inoculated wound sites of Kalanchoe leaves. Pluses denote virulence of strains maintained on plants at 20°C, and pluses in parentheses denote virulence of strains maintained on plants at 28°C. See the text for experimental details.

  • c Mixed infections with the T-DNA deletion strain LBA4404 (35). NA, not applicable (strains exhibiting wild-type virulence cannot be tested for export of individual substrates by mixed infection assays).

  • d Mixed infections with the virE2 mutant mx358.

  • e Conjugation assays with i4 mutant strains as donors and A348 Spcr as recipient. Values are transconjugants per donor cell.

  • f T-pilus production as monitored by abundance of exocellular VirB2 pilin. Pluses denote relative abundance of exocellular pilin isolated from strains induced for vir gene expression at 20°C, and pluses in parentheses denote the relative abundance of exocellular pilin from strains induced at 28°C.