PMID:12100554

Citation	Fidopiastis, PM, Miyamoto, CM, Jobling, MG, Meighen, EA and Ruby, EG (2002) LitR, a new transcriptional activator in Vibrio fischeri, regulates luminescence and symbiotic light organ colonization. Mol. Microbiol. 45:131-43
Abstract	Vibrio fischeri is the bacterial symbiont within the light-emitting organ of the sepiolid squid Euprymna scolopes. Upon colonizing juvenile squids, bacterial symbionts grow on host-supplied nutrients, while providing a bioluminescence that the host uses during its nocturnal activities. Mutant bacterial strains that are unable to emit light have been shown to be defective in normal colonization. A 606 bp open reading frame was cloned from V. fischeri that encoded a protein, which we named LitR, that had about 60% identity to four related regulator proteins: Vibrio cholerae HapR, Vibrio harveyi LuxR, Vibrio parahaemolyticus OpaR and Vibrio vulnificus SmcR. When grown in culture, cells of V. fischeri strain PMF8, in which litR was insertionally inactivated, were delayed in the onset of luminescence induction and emitted only about 20% as much light per cell as its parent. Protein-binding studies suggested that LitR enhances quorum sensing by regulating the transcription of the luxR gene. Interestingly, when competed against its parent in mixed inocula, PMF8 became the predominant symbiont present in 83% of light organs. Thus, the litR mutation appears to represent a novel class of mutations in which the loss of a regulatory gene function enhances the bacterium's competence in initiating a benign infection.
Links	PubMed
Keywords	Amino Acid Sequence; Animals; Bacterial Proteins/chemistry; Bacterial Proteins/metabolism; Decapodiformes/anatomy & histology; Decapodiformes/microbiology; Gene Expression Regulation, Bacterial; Light; Luminescent Measurements; Molecular Sequence Data; Repressor Proteins/genetics; Repressor Proteins/metabolism; Sequence Analysis, DNA; Symbiosis; Trans-Activators/chemistry; Trans-Activators/genetics; Trans-Activators/metabolism; Vibrio/genetics; Vibrio/growth & development; Vibrio/metabolism; Vibrio/physiology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
VIBF1:Q5E2S4	involved_in	GO:0008218: bioluminescence	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
VIBF1:Q5E2S4	involved_in	GO:0010628: positive regulation of gene expression	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete
VIBF1:Q5E2S4		GO:0010628: positive regulation of gene expression	ECO:0000314:		P		Table 2: shows the effect of LitR on the expression of beta-galactosidase.	complete CACAO 8831
VIBF1:Q5E2S4		GO:0008218: bioluminescence	ECO:0000315:		P		In Figure 5, V. fischeri strain PMF8, in which litR was insertionally inactivated, showed delayed onset of luminescence induction and emitted only about 20% as much light per cell as its parent.	complete CACAO 9002
VIBFI:H1R1D7		GO:0006355: regulation of transcription, DNA-dependent	IMP: Inferred from Mutant Phenotype:	P	Table 1 shows the luminescence of various litR genotypes.	complete CACAO 8728
VIBFI:H1R1D7		GO:0006351: transcription, DNA-dependent	IDA: Inferred from Direct Assay:	P	Table 2: shows the effect of LitR on the luminescence response using a beta-galactosidase assay.	complete CACAO 8729

References

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