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Sunao Iyoda

Publications and source records attributed to Sunao Iyoda.

6 recordsLinked to original sources
PubMed2026

Trimeric autotransporter adhesins driving chain-like adhesion diversify surface colonization strategies in Shiga toxin-producing Escherichia coli.

Bacteria frequently colonize host and environmental surfaces under fluid flow. Chain-like adherence pattern (CLAP) is an EibG-mediated surface colonization phenotype of certain Shiga toxin-producing Escherichia coli (STEC) that lack the locus of enterocyte effacement (LEE). EibG, an immunoglobulin-binding trimeric autotransporter adhesin, drives CLAP, but the temporal dynamics and genetic diversity underlying chain formation remain unclear. Here, we use live-cell time-lapse imaging to show that chains arise from single cells that elongate and divide without separation. Under flow, chains resist detachment and undergo shear-dependent fragmentation at cell-cell junctions, releasing viable clonal units that disperse downstream. Comparative genomics reveals diversity among EibG-related adhesins and identifies distinct lineages, including chain-like adhesins (Cla) that mediate CLAP while lacking IgG binding. Screening of 1,354 genomes from England shows that claB is present in 95.6% of strains from major LEE-negative STEC serotypes, highlighting its epidemiological prevalence. Targeted mutagenesis demonstrates that chain formation and IgG binding are mediated by distinct structural domains, revealing the modular functional architecture of these adhesins. Furthermore, we show that EibG, ClaA, and ClaB confer robust resistance to complement-mediated killing. Collectively, these findings establish CLAP as a dynamic, surface-associated strategy of LEE-negative STEC and reveal diversification among adhesins that drive this behavior.

Bacterial Adhesion↗
PubMed2002

[PulseNet Japan: surveillance system for the early detection of diffuse outbreak based on the molecular epidemiological method].

As the foods are stocked below freezing and widely distributed, a kind of food-borne outbreak which occurs in separate regions or in different time, so called "diffuse outbreak", has been found at the present day. Unless the outbreak is early recognized, the number of victims would increase. Some methods have been developed to analyze the relatedness of bacteria isolated from the patients of enteric infections. PFGE, pulsed-field gel electrophoresis, is one of the methods and powerful to discriminate the difference in nucleotide sequences among bacterial genomes. Availability of PFGE analysis is appreciated to examine the linkage of each incident of food-borne infections in epidemiological investigation. A PFGE network, PulseNet Japan, is now under construction among National Institute of Infectious Diseases, local Health Institutes and Ministry of Health, Labour and Welfare.

DNA, Bacterial↗
PubMed2002

High genomic diversity of enterohemorrhagic Escherichia coli isolates in Japan and its applicability for the detection of diffuse outbreak.

Genotyping of 1,102 enterohemorrhagic Escherichia coli isolates by the use of pulsed-field gel electrophoresis (PFGE) carried out from January to November 2000 has revealed the high genomic diversity of these isolates in Japan. By combining the results of genotyping of the isolates with the information from other epidemiological investigations of the cases, we identified a diffuse outbreak in Japan in the year 2000 that seemed to be sporadic but was actually linked. Isolates with only the Shiga toxin 2 gene derived from patient specimens and the contaminated food involved in this diffuse outbreak showed an indistinguishable PFGE profile and the same phage type. Based on the diversity of genotypes among the isolates of enterohemorrhagic E. coli O157:H7/- in Japan, we suggest the presence of a few other possible diffuse outbreaks due to the organisms, showing indistinguishable genotypes.

Disease Outbreaks↗
PubMed2000

Genotypic variations of Shiga toxin-converting phages from enterohaemorrhagic Escherichia coli O157: H7 isolates.

Pulsed-field gel electrophoresis (PFGE) analysis revealed that enterohaemorrhagic Escherichia coli (EHEC) O157:H7 strains had considerable variations in their genomes. This study investigated whether or not the molecular profile of Shiga toxin (Stx) 1- and Stx2-converting phages isolated from EHEC O157:H7 strains, derived from various sources in the USA and Japan, corresponded to the variations of host strains' genotypes as determined by PFGE. A total of 51 Stx-converting phages including 12 Stx1-converting phages and 37 Stx2-converting phages was isolated from seven USA isolates and 20 Japanese isolates. The average Dice coefficient values showed 44% similarity between phage DNAs in Stx2-converting phages digested with SmaI and 55% in Stx1-converting phages digested with HindIII, indicating considerable variation among phage DNA. In particular, restriction fragment length polymorphism (RFLP) patterns of Stx2-converting phage DNA varied according to the PFGE type of their host strain, which suggests that the phage genomes have altered their genotypic characteristics with those of host genomes. However, there are several exceptions: the RFLP patterns of some Stx2-converting phages were quite similar irrespective of the different genotypes of the host strains, indicating that horizontal transfer of Stx2-converting phage may also occur under some circumstances.

Bacterial Toxins↗
PubMed1999

Structure and expression of the fliA operon of Salmonella typhimurium.

The fliA gene encodes the flagellum-specific sigma factor sigma28 In Salmonella typhimurium. The transcription in vivo and in vitro of this gene was analysed and it was found that there are two promoters for the expression of this gene. One is a class 2 promoter which is recognized by sigma70-RNA polymerase in the presence of the FlhD and FlhC activator proteins. The other is a class 3 promoter which is recognized by sigma28-RNA polymerase. Therefore, the fliA operon is under dual positive control from FlhD/FlhC and from FliA itself. The nucleotide sequence downstream of the fliA gene was determined. The sequence contains two ORFs following the fliA gene. On the basis of their sequence homology, it is concluded that these two correspond to the fliZ and fliY genes of Escherichia coil. Northern blot analysis revealed that the fliZ gene is transcribed from the fliA promoters, whereas the fliY gene is transcribed from both the fliA promoters and its own FlhD/FlhC-independent promoter. A fliZ-disruption mutant was constructed by inserting a kanamycin-resistance gene cassette into the fliZ gene on the chromosome. The mutant showed poor motility, and introduction of a fliZ+ plasmid into this mutant restored the wildtype level of motility. These results suggest that the fliZ gene may be required for expression of maximal motility.

Amino Acid Sequence↗