Galactofuranosyl residues are present in various microorganisms but not in mammals. In this study, we identified a human lectin binding to galactofuranosyl residues and named this protein human intelectin (hIntL). The mature hIntL was a secretory glycoprotein consisting of 295 amino acids and N-linked oligosaccharides, and its basic structural unit was a 120-kDa homotrimer in which 40-kDa polypeptides were bridged by disulfide bonds. The hIntL gene was split into 8 exons on chromosome 1q21.3, and hIntL mRNA was expressed in the heart, small intestine, colon, and thymus. hIntL showed high levels of homology with mouse intelectin, Xenopus laevis cortical granule lectin/oocyte lectin, lamprey serum lectin, and ascidian galactose-specific lectin. These homologues commonly contained no carbohydrate recognition domain, which is a characteristic of C-type lectins, although some of them have been reported as Ca 2؉ -dependent lectins. Recombinant hIntL revealed affinities to D-pentoses and a D-galactofuranosyl residue in the presence of Ca 2؉ , and recognized the bacterial arabinogalactan of Nocardia containing D-galactofuranosyl residues. These results suggested that hIntL is a new type lectin recognizing galactofuranose, and that hIntL plays a role in the recognition of bacteria-specific components in the host.In host defense, the recognition of bacterial components is important for induction of immune responses. The cell wall components of pathogens have various biological activities and contain the bacteria-specific carbohydrate chains that do not exist in mammals. The recognition of these carbohydrate chains is useful to induce the cellular responses and fluidphase immune reactions for elimination of pathogens.In the innate immune response, the bacterial carbohydrate chains are recognized by the animal lectins that are present on cells as phagocytosis receptors or in plasma as opsonins or agglutinins. As a phagocytosis receptor, the mannose receptor binds materials containing terminal mannosyl residues such as zymosan and enhances their clearance by phagocytes (1, 2).The collectins and the ficolins are soluble lectins, and these lectins function as opsonins or agglutinins for bacteria (3)(4)(5)(6). In addition, the mannose-binding lectin (MBL), 1 a typical collectin, and ficolin/P32 form complexes with MBL-associated serine proteases in plasma. Binding of these complexes to targets activates the complement system, and complement activation induces opsonization of the targets by phagocytes and the target killing by formation of the membrane attack complex (7-9). This lectin-dependent complement activation pathway is named the lectin pathway and plays important roles in innate immunity (10, 11). These biological defense lectins commonly have affinity to mannose or N-acetylglucosamine, and binding is sustained by Ca 2ϩ (1-6), although the opposite results have been reported with regard to the Ca 2ϩ dependence of ficolins (5, 6, 12). On the other hand, animal lectins also include a group of lectins that have affinity to...

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The suhB gene is located at 55 min on the Escherichia coli chromosome and encodes a protein of 268 amino acids. Mutant alleles of suhB have been isolated as extragenic suppressors for the protein secretion mutation (secY24), the heat shock response mutation (rpoH15), and the DNA synthesis mutation (dnaB121) (K. Shiba, K. Ito, and T. Yura, J. Bacteriol. 160:696-701, 1984; R. Yano, H. Nagai, K. Shiba, and T. Yura, J. Bacteriol. 172:2124-2130, 1990; S. Chang, D. Ng, L. Baird, and C. Georgopoulos, J. Biol. Chem. 266:3654-3660, 1991). These mutant alleles of suhB cause cold-sensitive cell growth, indicating that the suhB gene is essential at low temperatures. Little work has been done, however, to elucidate the role of the product of suhB in a normal cell and the suppression mechanisms of the suhB mutations in the aforementioned mutants. The sequence similarity shared between the suhB gene product and mammalian inositol monophosphatase has prompted us to test the inositol monophosphatase activity of the suhB gene product. We report here that the purified SuhB protein showed inositol monophosphatase activity. The kinetic parameters of SuhB inositol monophosphatase (K m ‫؍‬ 0.071 mM; V max ‫؍‬ 12.3 mol/min per mg) are similar to those of mammalian inositol monophosphatase. The ssyA3 and suhB2 mutations, which were isolated as extragenic suppressors for secY24 and rpoH15, respectively, had a DNA insertion at the 5 proximal region of the suhB gene, and the amount of SuhB protein within mutant cells decreased. The possible role of suhB in E. coli is discussed.The suhB gene was first identified as the locus for the ssyA3(Cs) mutation that was isolated as an extragenic suppressor for the secY24(Ts) mutant (31). The ssyA3 mutation restored the defect in protein secretion caused by the secY24 mutation (33) and rescued the temperature-sensitive cell growth of secY24 mutant cells. The ssyA3 mutation caused cold-sensitive cell growth by itself and impaired protein synthesis was observed in the ssyA3 mutant at low temperatures (31). The cold-sensitive growth of the ssyA3 mutant was rescued by introduction of the wild-type copy of suhB, indicating that ssyA3 is a mutant allele of suhB (40). The suhB2(Cs) mutation is another allele of suhB and was isolated as an extragenic suppressor of the rpoH15(Ts) mutation. The rpoH15 mutant gene produces an altered 32 protein and causes a defect in the induction of heat shock proteins at higher temperatures (42). The suhB2(Cs) mutation rescued the temperature-sensitive cell growth of the rpoH15 mutant and partially restored heat shock induction in the mutant cell (40). A coldsensitive mutation was also mapped in the suhB locus as an extragenic suppressor for the dnaB121(Ts) mutation that inhibits replication of phage (2). Thus, mutant alleles of suhB have effects on diverse cell activities, including protein export, stress response, and DNA replication.The suhB gene encodes a protein of 268 amino acids (40), and the primary structure of its translated product shows a high level of similarity t...

A cytolethal distending toxin (cdt) gene-based species-specific multiplex PCR assay for the detection of cdtA, cdtB or cdtC gene of Campylobacter jejuni, Campylobacter coli or Campylobacter fetus, respectively, was developed and evaluated with 76 Campylobacter strains belonging to seven different species and 131 other bacterial strains of eight different genera. The cdtA, cdtB or cdtC gene of C. jejuni, C. coli or C. fetus, respectively, could be successfully amplified using the corresponding set of primers in a highly species-specific manner. Furthermore, the specific primer set for the cdtA, cdtB or cdtC gene of a particular species could amplify the desired gene from a mixture of DNA templates of any of two or all three species. The detection limit of C. jejuni, C. coli or C. fetus was 10-100 CFU tube(-1) by the multiplex PCR assay on the basis of the presence of the cdtA, cdtB or cdtC gene. These data indicate that the cdt gene-based multiplex PCR assay may be useful for rapid and accurate detection as well as identification of Campylobacter strains in a species-specific manner.