FIG. 6.

Protease susceptibility of the ³⁵S-labelled fdo gene products. (A) Proteins were labelled with l-[³⁵S]methionine-cysteine in K38 harboring pGP1-2 after induction at 42°C and addition of rifampin by the method of Tabor and Richardson (41). Cells were converted to spheroplasts and incubated with or without proteinase K or trypsin. Lane 1, untreated cell extracts; lane 2, untreated spheroplasts; lane 3, spheroplasts with 2.5 mg of trypsin/ml; lane 4, trypsin-solubilized fraction; lane 5, spheroplasts with 300 μg of proteinase K/ml; lane 6, proteinase K-solubilized fraction; lane 7, lysed spheroplasts with 300 μg of proteinase K/ml; lane 8, proteinase K-solubilized fraction (lysed spheroplasts); lane 9, lysed spheroplasts. (B) The same samples were subjected to Western blotting using anti-HYD2 antibodies. The three subunits, α, β, and γ, of FDH-O, as well as the large subunit (61 kDa), the small subunit (30 kDa), and the trypsin-released small-subunit derivative (25 kDa) of HYD2 are indicated on the right.