Phenotypes of Campylobacter jejuni luxS mutants are depending on strain background, kind of mutation and experimental conditions

Linda Adler; Thomas Alter; Soroush Sharbati; Greta Gölz

doi:10.1371/journal.pone.0104399

Phenotypes of Campylobacter jejuni luxS mutants are depending on strain background, kind of mutation and experimental conditions

PLoS One. 2014 Aug 5;9(8):e104399. doi: 10.1371/journal.pone.0104399. eCollection 2014.

Authors

Linda Adler¹, Thomas Alter¹, Soroush Sharbati², Greta Gölz¹

Affiliations

¹ Institute of Food Hygiene, Freie Universität Berlin, Berlin, Germany.
² Institute of Veterinary Biochemistry, Freie Universität Berlin, Berlin, Germany.

Abstract

Since the discovery that Campylobacter (C.) jejuni produces Autoinducer 2 (AI-2), various studies have been conducted to explore the function and role of AI-2 in C. jejuni. However, the interpretation of these analyses has been complicated by differences in strain backgrounds, kind of mutation and culture conditions used. Furthermore, all research on AI-2 dependent phenotypes has been conducted with AI-2 synthase (luxS) mutants. This mutation also leads to a disruption of the activated-methyl-cycle. Most studies lack sufficient complementation resulting in not knowing whether phenotypes of luxS mutants depend on disrupted metabolism or lack of AI-2. Additionally, no AI-2 receptor has been found yet. All this contributes to an intensive discussion about the exact role of AI-2 in C. jejuni. Therefore, we examined the impact of different experiment settings on three different C. jejuni luxS mutants on growth and motility (37°C and 42°C). Our study showed that differing phenotypes of C. jejuni luxS mutants depend on strain background, mutation strategy and culture conditions. Furthermore, we complemented experiments with synthetic AI-2 or homocysteine as well as the combination of both. Complementation with AI-2 and AI-2+homocysteine significantly increased the cell number of C. jejuni NCTC 11168ΔluxS in stationary phase compared to the non-complemented C. jejuni NCTC 11168ΔluxS mutant. Genetic complementation of both C. jejuni 81-176 luxS mutants resulted in wild type comparable growth curves. Also swarming ability could be partially complemented. While genetic complementation restored swarming abilities of C. jejuni 81-176ΔluxS, it did not fully restore the phenotype of C. jejuni 81-176::luxS, which indicates that compensatory mutations in other parts of the chromosome and/or potential polar effects may appear in this mutant strain. Also with neither synthetic complementation, the phenotype of the wild type-strains was achieved, suggesting yet another reason for differing phenotypes other than communication and methionine metabolism for C. jejuni luxS mutants.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Bacterial Proteins / genetics*
Bacterial Proteins / metabolism
Campylobacter jejuni / genetics*
Campylobacter jejuni / growth & development
Campylobacter jejuni / metabolism
Carbon-Sulfur Lyases / genetics*
Carbon-Sulfur Lyases / metabolism
Genetic Complementation Test
Mutation*
Phenotype*

Substances

Bacterial Proteins
Carbon-Sulfur Lyases
LuxS protein, Bacteria

Grants and funding

GG was funded by the German Federal Office for Agriculture and Food within the project InnoStep (http://www.ble.de/DE/07_DieBLE/dieble_node.html). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.