ABSTRACT
A hybridisation analysis of a genomic clone library of Rhizobium galegae HAMBI 1174 located four EcoRI fragments homologous to the nod-box promoter sequence of Sinorhizobium meliloti in two separate gene regions. Two of the five nod-boxes detected in the R. galegae genome were carried on a single cosmid clone, pRg30, upstream from the nodABCIJ and nodF genes, whereas the other three nod-boxes were carried on a different cosmid clone, pRg10. Hybridisations with various nod gene probes from S. meliloti and Rhizobium leguminosarum species detected a nodD homolog in pRg10. The sequence data obtained from regions adjacent to each nod-box in pRg10 confirmed the presence of a second nodD in the R. galegae genome and, in addition, revealed the presence of nodN, nodU, dctA nifH and nifQ-like genes in pRg10. Thus, by using a promoter-specific nod-box probe we could identify a new region carrying genes involved in nitrogen fixation and host specificity functions.
Subject(s)
Genes, Bacterial , Plant Roots/microbiology , Promoter Regions, Genetic , Rhizobium/genetics , Symbiosis/genetics , Base Sequence , Cosmids , Molecular Sequence Data , Nitrogen Fixation , Restriction Mapping , Sequence Analysis, DNA , Sequence Homology, Nucleic AcidABSTRACT
The adhesion of the S fimbriae of meningitis-associated Escherichia coli O18ac:K1:H7 to the cellular and the plasma forms of human fibronectin was studied. E. coli HB101(pAZZ50) expressing the complete S-fimbria II gene cluster of E. coli O18 adhered to cellular fibronectin (cFn) on glass but not to plasma fibronectin (pFn). Adhesion to cFn was specifically inhibited by neuraminidase treatment of cFn as well as by incubation of the bacteria with sialyl-alpha2-3-lactose, a receptor analog of the S fimbriae. No significant adhesion to cFn or pFn was detected with E. coli HB101(pAZZ50-67) expressing S fimbriae lacking the SfaS lectin subunit. Strain HB101(pAZZ50) also adhered to a human fibroblast cell culture known to be rich in cFn, and the adhesion was specifically inhibited in the presence of polyclonal antibodies to cFn. The results show that the SfaS lectin of the S fimbriae mediates the adherence of meningitis-associated E. coli to sialyl oligosaccharide chains of cFn.
Subject(s)
Bacterial Adhesion/physiology , Escherichia coli Infections/etiology , Escherichia coli/physiology , Escherichia coli/pathogenicity , Fibronectins/metabolism , Fimbriae, Bacterial/physiology , Meningitis, Bacterial/etiology , Carbohydrate Metabolism , Carbohydrates/chemistry , Cell Line , Escherichia coli/genetics , Escherichia coli Infections/microbiology , Fibronectins/chemistry , Fimbriae, Bacterial/genetics , Genes, Bacterial , Humans , In Vitro Techniques , Meningitis, Bacterial/microbiology , Multigene Family , Protein BindingABSTRACT
The effect of the plasminogen activator Pla of Yersinia pestis on the adhesiveness of bacteria to the mammalian extracellular matrix was determined. Y. pestis KIM D27 harbors the 9.5-kb plasmid pPCP1, encoding Pla and pesticin; the strain efficiently adhered to the reconstituted basement membrane preparation Matrigel, to the extracellular matrix prepared from human lung NCI-H292 epithelial cells, as well as to immobilized laminin. The isogenic strain Y. pestis KIM D34 lacking pPCP1 exhibited lower adhesiveness to both matrix preparations and to laminin. Both strains showed weak adherence to type I, IV, and V collagens as well as to human plasma and cellular fibronectin. The Pla-expressing recombinant Escherichia coli LE392(pC4006) exhibited specific adhesiveness to both extracellular matrix preparations as well as to laminin. The Pla-expressing strains showed a low-affinity adherence to another basement membrane component, heparan sulfate proteoglycan, but not to chondroitin sulfate proteoglycan. The degradation of radiolabeled laminin, heparan sulfate proteoglycan, or human lung extracellular matrix by the Pla-expressing recombinant E. coli required the presence of plasminogen, and degradation was inhibited by the plasmin inhibitors aprotinin and alpha2-antiplasmin. Our results indicate a function of Pla in enhancing bacterial adhesion to extracellular matrices. Y. pestis also exhibits a low level of Pla-independent adhesiveness to extracellular matrices.
Subject(s)
Bacterial Adhesion , Bacterial Proteins , Basement Membrane/microbiology , Extracellular Matrix/microbiology , Plasminogen Activators/biosynthesis , Yersinia pestis/pathogenicity , Collagen , Drug Combinations , Epithelial Cells , Escherichia coli/genetics , Escherichia coli/pathogenicity , Humans , In Vitro Techniques , Laminin , Lung/cytology , Plasminogen Activators/genetics , Proteoglycans , Recombinant Proteins/biosynthesisABSTRACT
A 36,688 bp fragment from the left arm of chromosome IV of saccharomyces cerevisiae was sequenced. Sequence analysis identified 20 complete non-overlapping open reading frames (ORFs) of at least 100 amino acids. Nine of these correspond to previously identified and sequenced genes: SIT4/PH1, FAD1, NAM1/MTF2, RNA11, SIR2/MAR1, NAT1/AAA1, PRP9, ACT2 and MPS1/RPK1. Three ORFs show homology to previously sequenced genes. One ORF exhibits a hypothetical yabO/yceC/YfiI family signature and one has the ATP-dependent helicase signature of the DEAD and DEAH box families. Six ORFs show no appreciable homology to any proteins in the database. One of these is identical to yeast expressed sequence tags and therefore corresponds to and expressed gene. In addition, two partial ORFs and 11 ORFs that are totally internal and are not likely to be functional were detected.
