Insertional inactivation of genes responsible for the D-alanylation of lipoteichoic acid in Streptococcus gordonii DL1 (Challis) affects intrageneric coaggregations
| Autor: | Daniel L. Clemans, Michael P. Heaton, Dmitri V. Debabov, Holly Sakone, R. Dwayne Lunsford, Paul E. Kolenbrander, Catherine J. Whittaker, Francis C. Neuhaus, Qunying Zhang |
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| Rok vydání: | 1999 |
| Předmět: |
Transposable element
DNA Bacterial Immunology Mutant Molecular Sequence Data Mutagenesis (molecular biology technique) medicine.disease_cause Microbiology Bacterial Adhesion medicine Humans Amino Acid Sequence Cloning Molecular Adhesins Bacterial Escherichia coli Peptide sequence DNA Primers Genetics Mouth biology Base Sequence Sequence Homology Amino Acid Streptococcus gordonii Streptococcus biology.organism_classification Teichoic Acids Microscopy Electron Mutagenesis Insertional Infectious Diseases Viridans streptococci Genes Bacterial DNA Transposable Elements Microscopy Electron Scanning Molecular and Cellular Pathogenesis Parasitology Lipoteichoic acid |
| Zdroj: | Infection and immunity. 67(5) |
| ISSN: | 0019-9567 |
| Popis: | Most human oral viridans streptococci participate in intrageneric coaggregations, the cell-to-cell adherence among genetically distinct streptococci. Two genes relevant to these intrageneric coaggregations were identified by transposon Tn 916 mutagenesis of Streptococcus gordonii DL1 (Challis). A 626-bp sequence flanking the left end of the transposon was homologous to dltA and dltB of Lactobacillus rhamnosus ATCC 7469 (formerly called Lactobacillus casei ). A 60-kb probe based on this flanking sequence was used to identify the homologous DNA in a fosmid library of S. gordonii DL1. This DNA encoded d -alanine- d -alanyl carrier protein ligase that was expressed in Escherichia coli from the fosmid clone. The cloned streptococcal dltA was disrupted by inserting an ermAM cassette, and then it was linearized and transformed into S. gordonii DL1 for allelic replacement. Erythromycin-resistant transformants containing a single insertion in dltA exhibited a loss of d -alanyl esters in lipoteichoic acid (LTA) and a loss of intrageneric coaggregation. This phenotype was correlated with the loss of a 100-kDa surface protein reported previously to be involved in mediating intrageneric coaggregation (C. J. Whittaker, D. L. Clemans, and P. E. Kolenbrander, Infect. Immun. 64:4137–4142, 1996). The mutants retained the parental ability to participate in intergeneric coaggregation with human oral actinomyces, indicating the specificity of the mutation in altering intrageneric coaggregations. The mutants were altered morphologically and exhibited aberrant cell septa in a variety of pleomorphs. The natural DNA transformation frequency was reduced 10-fold in these mutants. Southern analysis of chromosomal DNAs from various streptococcal species with the dltA probe revealed the presence of this gene in most viridans streptococci. Thus, it is hypothesized that d -alanyl LTA may provide binding sites for the putative 100-kDa adhesin and scaffolding for the proper presentation of this adhesin to mediate intrageneric coaggregation. |
| Databáze: | OpenAIRE |
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