<p>Listeria monocytogenes is the cause of human listeriosis, a food borne disease with high mortality. Serotypes 1/2a, 1/2b, and 4b account for most cause of illness. Serotype 4b is of special interest, for its high implication in foodborne outbreaks. Two loci were previously found to be involved in serotype-specific surface antigen expression of L. monocytogenes serotype 4b. One mutant, 27B6, derived from L.monocytogenes serotype 4b strain 2381L (Jalisco cheese outbreak), was found to be negative in immunoblot reactions with all three serotype 4b-specific MAbs C74.22, C74.33, and C74.180. Chromatographic analysis showed markedly reduced levels of two sugar substituents on the teichoic acid backbone, compared with the wild type strain. The mutant was furthermore resistant to Listeria species-specific phage A511, while still sensitive to serotype 4b-specific phage 2671. In this study, the transposon localized in a new genomic region (locus III). The genes in this region had homologues in the database involved in galactose metabolism, including galM, galE, and pgm. The transposon in 27B6 was found to be in the putative pgm. Interestingly, although inactivation of the putative pgm affected the presentation of both serotype-specific sugar substituents on the teichoic acid, the gene was not found to be unique to serotype 4b. The gene pgm was present in L.monocytogenes serotypes other than 4b, while it was absent or highly divergent in other species. An in-frame deletion of pgm was constructed, showing similar phenotypes as those of the initial transposon mutant 27B6. The wild type pgm sequence could successfully complement mutant 27B6 in-trans, restoring wild-type reactivity with MAbs, as well as phage A511 sensitivity. In conclusion, this newly characterized genomic region of L.monocytogenes may function in sugar metabolism and is possibly associated with cell wall teichoic acid glycosylation in serotype 4b, being required for expression of serotype 4b-specific antigenic determinants as well as receptors for phage A511. <P>
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-20010711-100349 |
| Date | 11 July 2001 |
| Creators | Li, Jianying |
| Contributors | Dr. Sophia Kathariou, Dr. Todd Klaenhammer, Dr. Fred Breidt |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-20010711-100349 |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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