Deletion of luxI increases luminescence of Vibrio fischeri .
Autor: | Bellissimo KA; Department of Microbiology, University of Georgia, Athens, Georgia, USA.; Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, USA., Septer AN; Department of Earth, Marine & Environmental Sciences, University of North Carolina, Chapel Hill, North Carolina, USA., Whistler CA; Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, USA., Rodríguez C; Department of Microbiology, University of Georgia, Athens, Georgia, USA., Stabb EV; Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, USA. |
---|---|
Jazyk: | angličtina |
Zdroj: | MBio [mBio] 2024 Oct 16; Vol. 15 (10), pp. e0244624. Date of Electronic Publication: 2024 Sep 24. |
DOI: | 10.1128/mbio.02446-24 |
Abstrakt: | Bioluminescence in Vibrio fischeri is regulated by a quorum-dependent signaling system composed of LuxI and LuxR. LuxI generates N- 3-oxohexanoyl homoserine lactone (3OC6-HSL), which triggers LuxR to activate transcription of the luxICDABEG operon responsible for bioluminescence. Surprisingly, a ∆ luxI mutant produced more bioluminescence than the wild type in culture. In contrast, a 4 bp duplication within luxI , resulting in a frameshift mutation and null allele, decreased luminescence tenfold. A second signaling system encoded by ainSR affects bioluminescence by increasing levels of LuxR, via the transcriptional activator LitR, and the N- octanoyl homoserine lactone (C8-HSL) signal produced by AinS is considered only a weak activator of LuxR. However, ainS is required for the bright phenotype of the ∆ luxI mutant in culture. When 3OC6-HSL was provided either in the medium or by expression of luxI in trans , all cultures were brighter, but the ∆ luxI mutant remained significantly brighter than the luxI frameshift mutant. Taken together, these data suggest that the enhanced bioluminescence due to the LuxI product 3OC6-HSL counteracts a negative cis -acting regulatory element within the luxI gene and that when luxI is absent the C8-HSL signal is sufficient to induce luminescence. Importance: The regulation of bioluminescence by Vibrio fischeri is a textbook example of bacterial quorum-dependent pheromone signaling. The canonical regulatory model is that an autoinducer pheromone produced by LuxI accumulates as cells achieve a high density, and this LuxI-generated signal stimulates LuxR to activate transcription of the lux operon that underlies bioluminescence. The surprising observation that LuxI is dispensable for inducing bioluminescence forces a re-evaluation of the role of luxI . More broadly, the results underscore the potential deceptiveness of complex regulatory circuits, particularly those in which bacteria produce multiple related signaling molecules. Competing Interests: The authors declare no conflict of interest. |
Databáze: | MEDLINE |
Externí odkaz: |