2a, lanes 6 and 7), whereas 83K25 produced appreciable amounts of 46–80-kDa Arg-gingipain bands (lane 8). Because 83K3, 83K10, and 83K25 (Fig. 1c) exhibited poor Arg-gingipain activity, these protein bands (detected in Fig. 2a, lanes 6–8, 10–12) were afunctional and likely

degradation products of Arg-gingipains. These results suggest that 83K25 secretes considerable amounts of abnormal Arg-gingipains. Figure 2b shows the expression of Lys-gingipain. In W83, Kgp was detected as a 50-kDa catalytic domain form (Sztukowska et al., 2004; Vanterpool et al., 2005a) in the cell extract fraction (Fig. 2b, lane 1) and the HSP fraction (lane 5). In contrast, 83K3, 83K10, and 83K25 produced a 190-kDa unprocessed form of Kgp (Sato et al., 2005) and 60- and 62-kDa Kgp 5 FU bands in cell

extract fractions (Fig. 2b, lanes 2–4). Sixty- and 62-kDa protein bands might be degradation products of Kgp. In the HSP fractions, faint 190- and 95-kDa bands were detected in 83K3 and 83K10 (Fig. 2b, lanes 6 and 7), whereas faint 190-, 105-, 95-, 62-, 60-, and 50-kDa Akt cancer bands were detected in 83K25 (Fig. 2a, lane 8). We think that a 50-kDa Kgp band (Fig. 2a, lane is a catalytic domain form exhibiting a weak Lys-gingipain activity (22% in the extracellular fraction from 83K25; Fig. 1c). The other Kgp bands are likely degradation products of Lys-gingipains; however, we did not know whether 190-kDa Lys-gingipain bands in the HSP fractions (Fig. 2b, lanes 6–8) are unprocessed forms of Kgp (Sato et al., 2005) or not. In the HSS fraction, both Lys-gingipain protein bands (Fig. 2b, lanes 9–12) and Lys-gingipain activity (data not shown) were poorly fractionated in W83 (Sztukowska et al., 2004) and the other mutants. These results suggest that 83K25 secretes small amounts of Lys-gingipains. Intact forms of lipopolysaccharide may anchor gingipains to the cell surface, contributing to the biogenesis of mature gingipains (Shoji et al., 2002; Sato et al., see more 2009). Lipopolysaccharide fractions were isolated from W83, 83K3, 83K10, and 83K25, subjected to SDS-PAGE, and were then visualized by silver staining. As shown in Fig. 3, lipopolysaccharide fractions from

83K3 (lane 2), 83K10 (lane 3), and 83K25 (lane 4) showed typical ladder band patterns, which are similar to that from W83 (lane 1), suggesting that lipopolysaccharide is not defected in 83K25 or the secretion-defective mutants of gingipains (83K3 and 83K10). PG534 contains a putative signal sequence in its N-terminal end (1st-MKEAIPRKNKYIKLNGIYRLSFILLCCLLCSQAAMA-36th) (Bendtsen et al., 2004), suggesting that PG534 is a secreted protein. Then, cytoplasmic/periplasmic, inner membrane, outer membrane, and extracellular fractions were prepared from W83 and 83K25. Inner membrane fractions and outer membrane fractions were verified by checking an inner membrane marker (the NADH–ferricyanide oxidoreductase activity; shown as FR activity in Fig. 4) and an outer membrane marker (an OmpA homologue PG694; Fig. 4).