FIG. 1.

Detection of PspA-associated proteins by in vivo cross-linking. Cells of strain CE1224 (lanes 1, 2, 5, and 6) or its pspA::kan derivative CE1343 (lanes 3, 4, 7, and 8), both carrying plasmid pMR05H2, were grown under phosphate limitation to induce the expression of mutant PhoE protein and, consequently, of the psp operon. After incubation of the cells with DSP (lanes 5 to 8), proteins were boiled in sample buffer, with (+) or without (−) DTT as indicated, and separated by SDS-11% PAGE, and this was followed by Western blotting using antibodies directed against PspA. The position of monomeric PspA is indicated. Asterisks depict proteins that nonspecifically react with anti-PspA antiserum. Relevant cross-linked adducts are indicated by carets. Blots were developed with 4-chloro-1-naphthol-H₂O₂ as the substrate. The positions of molecular mass marker proteins are indicated at the right (in kilodaltons).