FIG. 2.

(A) Effects of various pil mutations on the expression and processing of the pilS product. Whole extracts of E. coli cells harboring pKK641A′ with the indicated pil mutations were separated by SDS-PAGE and subjected to Western blot analysis with antipilin antiserum. (B) Effects of pil mutations on the formation of thin pili. A thin pilus fraction was prepared from the culture media of E. coli cells harboring pKK641A′ with the indicated pil mutations. Proteins were separated by SDS-PAGE and subjected to Western blot analysis with antipilin antiserum. The positions of prepilin (22 kDa) and pilin (19 kDa) are indicated on the right.