Biomedical subjects

Jason M Andrus

Publications and source records attributed to Jason M Andrus.

3 recordsLinked to original sources

PubMed2006

Human epithelial-specific response to pathogenic Campylobacter jejuni.

The gastrointestinal epithelia of mammals are tolerant of their resident gut microbiota but are usually highly responsive to entero-pathogens; the host-specific responses have not been well characterized. To this end, the transcriptional responses of cultured human (Caco-2) and murine (CT-26) colonic epithelial cells were compared after exposure with the microfloral bacterium Lactobacillus reuteri or the human gastrointestinal pathogen Campylobacter jejuni. When in bacterial broth, both species elicit a stronger differential gene expression response in human colonic cells compared with mouse colonic cells. However, when these data are adjusted to remove bacterial broth effects, only human colonic epithelia exposed to C. jejuni show altered gene expression, suggesting that the human pathogen C. jejuni induces a host-specific response. The genes with altered expression are involved in growth, transcription, and steroid biosynthesis. Interestingly, human genes involved in cell polarity and water transport were significantly changed in response to C. jejuni exposure, linking infection with gastrointestinal disease. This study demonstrates that mouse and human colonic epithelia remain relatively unresponsive to commensal bacterial challenge, while the human pathogen C. jejuni elicits a host-specific response.

Animals↗

PubMed2004

Expression of a heterologous manganese superoxide dismutase gene in intestinal lactobacilli provides protection against hydrogen peroxide toxicity.

In living organisms, exposure to oxygen provokes oxidative stress. A widespread mechanism for protection against oxidative stress is provided by the antioxidant enzymes: superoxide dismutases (SODs) and hydroperoxidases. Generally, these enzymes are not present in Lactobacillus spp. In this study, we examined the potential advantages of providing a heterologous SOD to some of the intestinal lactobacilli. Thus, the gene encoding the manganese-containing SOD (sodA) was cloned from Streptococcus thermophilus AO54 and expressed in four intestinal lactobacilli. A 1.2-kb PCR product containing the sodA gene was cloned into the shuttle vector pTRK563, to yield pSodA, which was functionally expressed and complemented an Escherichia coli strain deficient in Mn and FeSODs. The plasmid, pSodA, was subsequently introduced and expressed in Lactobacillus gasseri NCK334, Lactobacillus johnsonii NCK89, Lactobacillus acidophilus NCK56, and Lactobacillus reuteri NCK932. Molecular and biochemical analyses confirmed the presence of the gene (sodA) and the expression of an active gene product (MnSOD) in these strains of lactobacilli. The specific activities of MnSOD were 6.7, 3.8, 5.8, and 60.7 U/mg of protein for L. gasseri, L. johnsonii, L. acidophilus, and L. reuteri, respectively. The expression of S. thermophilus MnSOD in L. gasseri and L. acidophilus provided protection against hydrogen peroxide stress. The data show that MnSOD protects cells against hydrogen peroxide by removing O(2)(.-) and preventing the redox cycling of iron. To our best knowledge, this is the first report of a sodA from S. thermophilus being expressed in other lactic acid bacteria.

Cloning, Molecular↗

PubMed2003

Molecular characterization and functional analysis of the manganese-containing superoxide dismutase gene (sodA) from Streptococcus thermophilus AO54.

This report describes the isolation, sequencing, and functional analysis of the sodA gene, encoding Mn-superoxide dismutase, from Streptococcus thermophilus AO54. The gene was found to encode a 201 amino acid polypeptide with 88 and 83% identity to SodA from Streptococcus mutans and Streptococcus agalacticae, respectively. Primer extension analysis revealed a transcriptional start site 27 nucleotides upstream of initiation codon. The gene was expressed in Escherichia coli and was able to rescue the growth of a sodAsodB mutant in a minimal-medium containing 10(-6)M paraquat. A sodA mutant of S. thermophilus was constructed and found to be more sensitive to aerobic growth than its parent strain. Supplementing the medium with MnCl(2) improved the growth of the mutant, only under microaerophilic conditions. The results suggest that sodA is essential for the aerobic growth of S. thermophilus. In the absence of functional SodA, manganese ions may provide partial protection against oxygen toxicity.

Amino Acid Sequence↗