FIG 6.
The Ser-Lys catalytic dyad of LepB2 is necessary for pilus assembly. (A) Multiple-sequence alignment of type 1 SPases from A. oris (LepB1 and LepB2), Mycobacterium leprae (LepB), Streptomyces coelicolor (Sip1), Bacillus anthracis (SipS), Bacillus subtilis (SipS), and Streptococcus pneumoniae (Spi) performed with CLUSTAL W (33). Conserved box B and box D, which contain the catalytic Ser and Lys residues (highlighted in black), respectively, are shown. Numbers indicate Ser and Lys positions in A. oris LepB2. (B) Supernatant (S) and cell wall (W) fractions were collected from MG1 and its isogenic derivatives. Equivalent protein samples were subjected to immunoblotting with anti-FimP antibody. (C) The same samples as in panel B were immunoblotted with anti-FimA antibody. The positions of fimbrial monomer (FimPM), HMW polymers (FimPP), and molecular mass markers are indicated.