For immunoblot analysis, HRP-conjugated goat anti-rabbit immunoglobulin G (IgG) (Bio-Rad) was used as the secondary antibody. pKS9 was digested with NcoI (in the sov) and KpnI (in a vector), blunted with T4 DNA polymerase, and ligated to create pKS20. A 0.6-kbp 3′-terminal region of sov was amplified from pKS9 by PCR with 5′-ATGGTACCTATCTCGAGATGTCGTAGTCCGCACTG-3′ (italics: KpnI and XhoI sites) and 5′-CAGGAAACAGCTATGACC-3′. The PCR product was digested with EcoRI and KpnI and cloned into a 5.6-kbp EcoRI–KpnI-digested
fragment from pKS9 to create pKS21. Similarly, a 0.65-kbp 3′-terminal region of the sov fragment was amplified with 5′-ATGGTACCTAGCTAGCTGAGCTGACAAGCGGATGG-3′ (italics: KpnI and NheI sites) and 5′-CAGGAAACAGCTATGACC-3′; then, the PCR product was digested with learn more EcoRI and KpnI and cloned into a 5.6-kbp EcoRI–KpnI-digested fragment from pKS9 to create pKS22. pKS24 was constructed by ligation of a 6.2-kbp NheI–KpnI-digested fragment from pKS22 and
an annealed-oligonucleotide linker, 5′-CTAGCTTCCCTATCACGAATTCGAATTTCGGCGTCAGCTAGGTAC-3′/5′-CTAGCTGACGCCGAAATTCGAATTCGTGATAGGGAAG-3′ (italics: BstBI site). pKS24 was digested with BstBI, blunted with T4 DNA polymerase, and ligated to construct pKS23. pKS24 was digested with BstBI and KpnI and ligated with an annealed-oligonucleotide linker [5′-CGAATTTCGGCGTGAGCTCGAGGTAC-3′/5′-CTCGAGCTCACGCCGAAATT-3′ (italics: SacI site)] to create pKS25, which contains a SacI site. pKS26–pKS31 were constructed by ligation find protocol of a 6.2-kbp SacI–KpnI-digested fragment from pKS25 with the following annealed-oligonucleotide linkers: 5′-TCTAGATATCAGATCTGGTAC-3′/5′-CAGATCTGATATCTAGAAGCT-3′ Fossariinae (for pKS26), 5′-TCCGTTGATATCAGATCTGGTAC-3′/5′-CAGATCTGATATCAACGGAAGCT-3′ (for pKS27), 5′-TCCGTTTCTGATATCAGATCTGGTAC-3′/5′-CAGATCTGATATCAGAAACGGAAGCT-3′
(for pKS28), 5′-TCCGTTTCAATTGATATCAGATCTGGTAC-3′/5′-CAGATCTGATATCAATTGAAACGGAAGCT-3′ (for pKS29), 5′-TCCGTTTCAATCTGTGATATCAGATCTGGTAC-3′/5′-CAGATCTGATATCACAGATTGAAACGGAAGCT-3′ (for pKS30), and 5′-TCCGTTTCAATCTGACGTGATATCAGATCTGGTAC-3′/5′-CAGATCTGATATCACGTCAGATTGAAACGGAAGCT-3′ (for pKS31). pKS20, pKS21, pKS22, pKS23, pKS24, pKS26, pKS27, pKS28, pKS29, pKS30, and pKS31 were linearized and used to construct P. gingivalis mutants 83K14, 83K15, 83K16, 83K17, 83K18, 83K19, 83K20, 83K21, 83K22, 83K23, and 83K24, respectively, by electroporation. Deletion mutations of 83K14–24 were confirmed similarly as described above. A P. gingivalis cell culture was centrifuged. The cell pellets were washed, suspended in PBS, and sonicated (with tip #3) to generate the cell extract fraction. The culture supernatant was collected as the extracellular fraction. To determine the expression of gingipains, 3 mL of supernatant was concentrated on an ultrafiltration membrane (10 000 MWCO), diluted with 8 M urea, and concentrated to 0.1 mL. Rgp activity was determined in Tris-HCl (100 mM, pH 8.