Takahiko Ishikawa

Learn More
Membranes allow the compartmentalization of biochemical processes and are therefore fundamental to life. The conservation of the cellular membrane, combined with its accessibility to secreted proteins, has made it a common target of factors mediating antagonistic interactions between diverse organisms. Here we report the discovery of a diverse superfamily(More)
BACKGROUND The type VI secretion system (T6SS) has emerged as a protein secretion system important to several gram-negative bacterial species. One of the common components of the system is Hcp, initially described as a hemolysin co-regulated protein in a serotype O17 strain of Vibrio cholerae. Homologs to V. cholerae hcp genes have been found in all(More)
The most recently discovered secretion pathway in gram-negative bacteria, the type VI secretion system (T6SS), is present in many species and is considered important for the survival of non-O1 non-O139 Vibrio cholerae in aquatic environments. Until now, it was not known whether there is a functionally active T6SS in wild-type V. cholerae O1 strains, the(More)
We identified and characterized the iron-binding protein Dps from Campylobacter jejuni. Electron microscopic analysis of this protein revealed a spherical structure of 8.5 nm in diameter, with an electron-dense core similar to those of other proteins of the Dps (DNA-binding protein from starved cells) family. Cloning and sequencing of the Dps-encoding gene(More)
We identified the mutated gene locus in a pigment-overproducing Vibrio cholerae mutant of strain A1552. The deduced gene product is suggested to be an oxidoreductase based on partial homology to putative homogentisate 1,2-dioxygenase in Pseudomonas aeruginosa and Mesorhizobium loti, and we propose that the gene VC1345 in the V. cholerae genome be denoted(More)
Many Gram-negative bacteria rely on a type VI secretion system (T6SS) to infect eukaryotic cells or to compete against other microbes. Common to these systems is the presence of two conserved proteins, in Vibrio cholerae denoted VipA and VipB, which have been shown to interact in many clinically relevant pathogens. In this study, mutagenesis of a defined(More)
To assess the humoral response to the influenza vaccine in patients undergoing R-CHOP therapy (rituximab combined with cyclophosphamide, doxorubicin, vincristine, and predonisolone) for non-Hodgkin lymphoma (NHL), the anti-hemagglutinin (HA) titer in 7 NHL patients undergoing therapy was compared with those in 10 control group subjects in the 2005/2006(More)
Bacillus cereus is known as a serious bacterial pathogen in neutropenic patients. B. cereus is often resistant to beta-lactams, including penicillins and cephalosporins. We report a case of fatal pneumonia caused by B. cereus in a patient with newly diagnosed acute myeloid leukemia (AML) during remission induction therapy. Cefepime was started for febrile(More)
In Vibrio cholerae, 41 chitin-inducible genes, including the genes involved in natural competence for DNA uptake, are governed by the orphan two-component system (TCS) sensor kinase ChiS. However, the mechanism by which ChiS controls the expression of these genes is currently unknown. Here, we report the involvement of a novel transcription factor termed(More)
In large classes, teachers find it difficult to care about the personality and ability of individual students. One of the ways to grasp the learning state of students is to conduct a number of short tests during every class. If a system can automatically give the appropriate instructions and teaching materials to individual students based on the test(More)