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Rodent and human genomes were screened to identify pseudogenes of the type 1 voltage-dependent anion channel (VDAC1) in mitochondria. In addition to the 16 pseudogenes of rat VDAC1 identified in our recent study, 15 and 13 sequences were identified as pseudogenes of VDAC1 in mouse and human genome, respectively; and 4, 2, and 1 sequences, showing lower similarities with the VDAC1 sequence, were identified as “possible pseudogene candidates” in rat, mouse, and human, respectively. No syntenic combination was observed between rodent and human pseudogenes, but 2 and 1 possible pseudogene candidates of VDAC1 of rat and mouse, respectively, were found to have syntenic counterparts in mouse and rat genome, respectively; and these syntenic counterparts were genuine VDAC1 pseudogenes. Therefore, syntenic combinations of pseudogenes of VDAC1 were useful not only for a better understanding of the phylogenetic divergence history of rodents but also for ascertaining possible pseudogene candidates as genuine pseudogenes.

Streptococcus anginosus is a member of the anginosus group streptococci, which form part of the normal human oral flora. In contrast to the pyogenic group streptococci, our knowledge of the virulence factors of the anginosus group streptococci, including S. anginosus, is not sufficient to allow a clear understanding of the basis of their pathogenicity. Generally, hemolysins are thought to be important virulence factors in streptococcal infections. In the present study, a sag operon homologue was shown to be responsible for beta-hemolysis in S. anginosus strains by random gene knockout. Interestingly, contrary to pyogenic group streptococci, beta-hemolytic S. anginosus was shown to have two tandem sagA homologues, encoding streptolysin S (SLS)-like peptides, in the sag operon homologue. Gene deletion and complementation experiments revealed that both genes were functional, and these SLS-like peptides were essential for beta-hemolysis in beta-hemolytic S. anginosus. Furthermore, the amino acid sequence of these SLS-like peptides differed from that of the typical SLS of S. pyogenes, especially in their propeptide domain, and an amino acid residue indicated to be important for the cytolytic activity of SLS in S. pyogenes was deleted in both S. anginosus homologues. These data suggest that SLS-like peptides encoded by two sagA homologues in beta-hemolytic S. anginosus may be potential virulence factors with a different structure essential for hemolytic activity and/or the maturation process compared to the typical SLS present in pyogenic group streptococci.

Background/Aim: The aim of this study was to develop an improved drug delivery system (DDS) tool with enhanced versatility in the cell-targeting step using as Z-domain, a modified IgG binding domain of protein A from Staphylococcus aureus, as an IgG adapter domain. Materials and Methods: The chimera protein expression system composed of the Z-domain and chimeric cholesterol-dependent cytolysin mutant named His-Z-CDC(ss)IS was constructed in Escherichia coli. His-Z-CDC(ss)IS was purified by Ni-affinity chromatography, and its abilities for controlled pore formation, membrane binding, IgG binding, and target cell-specific delivery of liposomes carrying medicine were investigated. Results and Discussion: His-Z-CDC(ss)IS purified by Ni-affinity chromatography indicated pore-forming activity only under disulfide bond reducing conditions. His-Z-CDC(ss)IS also demonstrated an ability to bind both IgG and cholesterol-embedded liposomes via its Z-domain and domain 4, respectively. Furthermore, anticarcinoembryonic antigen (CEA) IgG-bound His-Z-CDC(ss)IS indicated effective delivery of liposomes carrying drugs to CEA-expressing cells. Conclusion: His-Z-CDC(ss)IS was revealed to be an improved DDS tool with enhanced versatility in cell targeting.

Background/Aim: Cholesterol-dependent cytolysins (CDCs) are pore-forming toxins from Gram-positive bacteria. The aim of this study was to investigate the potential of a CDC, intermedilysin, as a drug-delivery system (DDS) for clinical application. Materials and Methods: Intermedilysin was modified by the addition of a disulfide bridge to regulate pore formation, by swapping domain 4 to provide cholesterol-binding capacity, and by the introduction of a targeting domain. The resultant chimera protein, His-LTBP-CDC(ss)IP, was investigated for its use as a DDS tool in vitro. Results: His-LTBP-CDC(ss)IP exhibited a regulated pore-forming capacity under reducing conditions. This chimera protein was able to deliver a drug-carrier liposome specifically to the target cell, to be endocytosed into the cell with subsequent release of the components into the cytoplasm. Conclusion: A chimera protein derived from the bacterial pore-forming toxin intermedilysin (His-LTBP-CDC(ss)IP) forms the basis for a novel DDS tool.