PMID:16385049

Citation	Herzberg, M, Kaye, IK, Peti, W and Wood, TK (2006) YdgG (TqsA) controls biofilm formation in Escherichia coli K-12 through autoinducer 2 transport.J. Bacteriol. 188:587-98
Abstract	YdgG is an uncharacterized protein that is induced in Escherichia coli biofilms. Here it is shown that deletion of ydgG decreased extracellular and increased intracellular concentrations of autoinducer 2 (AI-2); hence, YdgG enhances transport of AI-2. Consistent with this hypothesis, deletion of ydgG resulted in a 7,000-fold increase in biofilm thickness and 574-fold increase in biomass in flow cells. Also consistent with the hypothesis, deletion of ydgG increased cell motility by increasing transcription of flagellar genes (genes induced by AI-2). By expressing ydgG in trans, the wild-type phenotypes for extracellular AI-2 activity, motility, and biofilm formation were restored. YdgG is also predicted to be a membrane-spanning protein that is conserved in many bacteria, and it influences resistance to several antimicrobials, including crystal violet and streptomycin (this phenotype could also be complemented). Deletion of ydgG also caused 31% of the bacterial chromosome to be differentially expressed in biofilms, as expected, since AI-2 controls hundreds of genes. YdgG was found to negatively modulate expression of flagellum- and motility-related genes, as well as other known products essential for biofilm formation, including operons for type 1 fimbriae, autotransporter protein Ag43, curli production, colanic acid production, and production of polysaccharide adhesin. Eighty genes not previously related to biofilm formation were also identified, including those that encode transport proteins (yihN and yihP), polysialic acid production (gutM and gutQ), CP4-57 prophage functions (yfjR and alpA), methionine biosynthesis (metR), biotin and thiamine biosynthesis (bioF and thiDFH), anaerobic metabolism (focB, hyfACDR, ttdA, and fumB), and proteins with unknown function (ybfG, yceO, yjhQ, and yjbE); 10 of these genes were verified through mutation to decrease biofilm formation by 40% or more (yfjR, bioF, yccW, yjbE, yceO, ttdA, fumB, yjiP, gutQ, and yihR). Hence, it appears YdgG controls the transport of the quorum-sensing signal AI-2, and so we suggest the gene name tqsA.
Links	PubMed Online version:10.1128/JB.188.2.587-598.2006
Keywords	Biofilms; Biological Transport; Escherichia coli K12; Escherichia coli Proteins; Gene Deletion; Genes, Bacterial; Homoserine; Lactones; Transcription, Genetic
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Main Points of the Paper

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Materials and Methods Used

• Biofilm, 96-well Assay (Herzberg et al. 2006)
  • Crystal violet
• Biofilm, Flow Cell Assay (Herzberg et al. 2006)
• Motility Assay (Herzberg et al. 2006)
• COMSTAT

Phenotype Annotations

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Species	Taxon ID	Strain	Gene (if known)	OMP	Phenotype	Details	Evidence	Notes
Escherichia coli			delydgG	increased biofilm formation	Other	assayed in 96-well plates when glucose was added to the medium	Staining	crystal violet assay
Escherichia coli			delydgG	increased biofilm formation	Other	assayed in continuous flow system	Microscopy	Figure 1
Escherichia coli			del ydgG	flat biofilm formation	Morphology	assayed in continuous flow system	Microscopy	Figure 1
Escherichia coli			del ydgG	biofilm morphology- large, irregularly shaped, smooth masses containing random protrusions	Morphology	assayed in continuous flow system	Microscopy	Figure 1
Escherichia coli			del ydgG	biofilm architecture- increased biomass	Morphology	increased biomass 574-fold after 24 hours	Microscopy	using COMSTAT computer program
Escherichia coli			del ydgG	increased substratum coverage	Morphology	increased substratum coverage 10-fold after 24 hours	Microscopy	using COMSTAT computer program
Escherichia coli			del ydgG	biofilm architecture-increased mean thickness	Morphology	increased mean thickness 7,000-fold after 24 hours	Microscopy	using COMSTAT computer program
Escherichia coli			del ydgG	biofilm architecture-decreased roughness coefficient	Morphology	decreased roughness coefficient 12-fold after 24 hours	Microscopy	using COMSTAT computer program
Escherichia coli			del ydgG	increase in swimming motility	Motility	6-fold increase compared to wt	Plating Assay
Escherichia coli			del ydgG	increased transcription of other genes	Expression	increased the transcription of the quorum-sensing response regulator of flagellum genes (qseB), flagellar synthesis genes (flhD, fliA, and fliC), and a motility gene (motA)	Other	Figure 2- beta-galactosidase activity
Escherichia coli			del ydgG	decreased extracellular AI-2 activity	Other		Other
Escherichia coli			del ydgG	increased intracellular AI-2 activity	Other		Other	Figure 3- lsrACDBFG transcription
Escherichia coli			del ydgG	decreased resistance to antimicrobials decreased drug susceptibility increased sensitivity to antimicrobials	Sensitivity to	crystal violet, spectinomycin, streptomycin sulfate, 2,6, dichloroquinone-4-chlorimide, chloramphenicol, amoxicillin	Plating Assay	MIC comparisons
Escherichia coli			del ydgG	change in differential gene expression in biofilms-	Expression	31% of genes differentially induced 8% of genes differentially repressed		Tables 2 and 3
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References

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