Fig. 4.

Effects of the G272R mutation on T pilus production, as monitored by assaying for the presence of VirB2 pilin and pilus-associated VirB5 on the cell surface by Western blotting and immunostaining of colonies and shear fractions with anti-VirB2 and anti-VirB5 antibodies, respectively. Corresponding analyses of the nonpolar ΔvirB2 and ΔvirB5 mutants show absence of antibody cross-reactivity and codependence of VirB2 and VirB5 for surface display. Bottom, steady-state cellular levels of VirB2 and VirB5.