LOCALIZATION OF THE PROTEIN VIRB1 INVOLVED IN CONTACT FORMATION DURING CONJUGATION AMONG AGROBACTERIUM CELLS

Supramembrane structures of Agrobacterium, which link cells during mat ing, were for the first time visualized using transmission electron mi croscopy. The initial cell contact was found to be mediated by long pi ll. Using colloidal gold-labeled, VirB1-specific antibodies, it was es tablished that VirB1 proteins enter into the composition of short pilu s-like structures, which emerge at the poles of acetosyringone (AS)-in duced agrobacterial cells. Labeling of non-centrifuged agrobacterial c ells on a nitrocellulose membrane using colloidal gold-conjugated anti bodies to VirB1 showed that the labeled complex could bind to AS-induc ed cells, but failed to form red stains during incubation with cells o f the Ti plasmidless A. tumefaciens strains LBA288 and UBAPF-2. (C) 19 98 Published by Elsevier Science B.V. All rights reserved.