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E. coli K-12 and EHEC genes regulated by SdiA.

Dyszel JL, Soares JA, Swearingen MC, Lindsay A, Smith JN, Ahmer BM - PLoS ONE (2010)

Bottom Line: We found that genes encoding the glutamate-dependent acid resistance system are up-regulated, and fliE is down-regulated, by sdiA.The genes of E. coli that respond to plasmid-based expression of sdiA are largely different than those that respond to chromosomal sdiA and/or AHL.This has significant implications for determining the true function of AHL detection by E. coli.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, The Ohio State University, Columbus, Ohio, United States of America.

ABSTRACT

Background: Escherichia and Salmonella encode SdiA, a transcription factor of the LuxR family that regulates genes in response to N-acyl homoserine lactones (AHLs) produced by other species of bacteria. E. coli genes that change expression in the presence of plasmid-encoded sdiA have been identified by several labs. However, many of these genes were identified by overexpressing sdiA on a plasmid and have not been tested for a response to sdiA produced from its natural position in the chromosome or for a response to AHL.

Methodology/principal findings: We determined that two important loci reported to respond to plasmid-based sdiA, ftsQAZ and acrAB, do not respond to sdiA expressed from its natural position in the chromosome or to AHLs. To identify genes that are regulated by chromosomal sdiA and/or AHLs, we screened 10,000 random transposon-based luciferase fusions in E. coli K-12 and a further 10,000 in E. coli O157:H7 for a response to AHL and then tested these genes for sdiA-dependence. We found that genes encoding the glutamate-dependent acid resistance system are up-regulated, and fliE is down-regulated, by sdiA. Gene regulation by sdiA of E. coli is only partially dependent upon AHL.

Conclusions/significance: The genes of E. coli that respond to plasmid-based expression of sdiA are largely different than those that respond to chromosomal sdiA and/or AHL. This has significant implications for determining the true function of AHL detection by E. coli.

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Related in: MedlinePlus

Cross streak assays of the E. coli K-12 and EHEC lux fusions.The chromosomal lux fusions and their respective sdiA mutants were grown in broth overnight. The strains were dripped down the plate perpendicular to 20 µl of EA then 20 µl of 10 µM oxoC6 (diagrammed in Panel A for all panels). Plates were incubated at 37°C for 7 hours then light emission was imaged using a C2400-32 intensified charge-coupled device camera with an Argus 20 image processor. A) AL4001/JLD800 (gadW), B) JLD604/JLD803 (fliE), C) JLD605/JLD804 (gadE), D) JLD607/JLD806 (yhiD), E) JLD610 /JLD809 (hdeA).
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pone-0008946-g010: Cross streak assays of the E. coli K-12 and EHEC lux fusions.The chromosomal lux fusions and their respective sdiA mutants were grown in broth overnight. The strains were dripped down the plate perpendicular to 20 µl of EA then 20 µl of 10 µM oxoC6 (diagrammed in Panel A for all panels). Plates were incubated at 37°C for 7 hours then light emission was imaged using a C2400-32 intensified charge-coupled device camera with an Argus 20 image processor. A) AL4001/JLD800 (gadW), B) JLD604/JLD803 (fliE), C) JLD605/JLD804 (gadE), D) JLD607/JLD806 (yhiD), E) JLD610 /JLD809 (hdeA).

Mentions: We also tested the fusions on solid LB agar using cross-streak assays (Figure 10). The fusions were clearly regulated by oxoC6 but not the solvent control EA. Four of the fusions were up-regulated in the presence of chromosomal sdiA (gadW, gadE, yhiD and hdeA), whereas the fliE promoter was down-regulated. This regulation was entirely dependent upon sdiA.


E. coli K-12 and EHEC genes regulated by SdiA.

Dyszel JL, Soares JA, Swearingen MC, Lindsay A, Smith JN, Ahmer BM - PLoS ONE (2010)

Cross streak assays of the E. coli K-12 and EHEC lux fusions.The chromosomal lux fusions and their respective sdiA mutants were grown in broth overnight. The strains were dripped down the plate perpendicular to 20 µl of EA then 20 µl of 10 µM oxoC6 (diagrammed in Panel A for all panels). Plates were incubated at 37°C for 7 hours then light emission was imaged using a C2400-32 intensified charge-coupled device camera with an Argus 20 image processor. A) AL4001/JLD800 (gadW), B) JLD604/JLD803 (fliE), C) JLD605/JLD804 (gadE), D) JLD607/JLD806 (yhiD), E) JLD610 /JLD809 (hdeA).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2812512&req=5

pone-0008946-g010: Cross streak assays of the E. coli K-12 and EHEC lux fusions.The chromosomal lux fusions and their respective sdiA mutants were grown in broth overnight. The strains were dripped down the plate perpendicular to 20 µl of EA then 20 µl of 10 µM oxoC6 (diagrammed in Panel A for all panels). Plates were incubated at 37°C for 7 hours then light emission was imaged using a C2400-32 intensified charge-coupled device camera with an Argus 20 image processor. A) AL4001/JLD800 (gadW), B) JLD604/JLD803 (fliE), C) JLD605/JLD804 (gadE), D) JLD607/JLD806 (yhiD), E) JLD610 /JLD809 (hdeA).
Mentions: We also tested the fusions on solid LB agar using cross-streak assays (Figure 10). The fusions were clearly regulated by oxoC6 but not the solvent control EA. Four of the fusions were up-regulated in the presence of chromosomal sdiA (gadW, gadE, yhiD and hdeA), whereas the fliE promoter was down-regulated. This regulation was entirely dependent upon sdiA.

Bottom Line: We found that genes encoding the glutamate-dependent acid resistance system are up-regulated, and fliE is down-regulated, by sdiA.The genes of E. coli that respond to plasmid-based expression of sdiA are largely different than those that respond to chromosomal sdiA and/or AHL.This has significant implications for determining the true function of AHL detection by E. coli.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, The Ohio State University, Columbus, Ohio, United States of America.

ABSTRACT

Background: Escherichia and Salmonella encode SdiA, a transcription factor of the LuxR family that regulates genes in response to N-acyl homoserine lactones (AHLs) produced by other species of bacteria. E. coli genes that change expression in the presence of plasmid-encoded sdiA have been identified by several labs. However, many of these genes were identified by overexpressing sdiA on a plasmid and have not been tested for a response to sdiA produced from its natural position in the chromosome or for a response to AHL.

Methodology/principal findings: We determined that two important loci reported to respond to plasmid-based sdiA, ftsQAZ and acrAB, do not respond to sdiA expressed from its natural position in the chromosome or to AHLs. To identify genes that are regulated by chromosomal sdiA and/or AHLs, we screened 10,000 random transposon-based luciferase fusions in E. coli K-12 and a further 10,000 in E. coli O157:H7 for a response to AHL and then tested these genes for sdiA-dependence. We found that genes encoding the glutamate-dependent acid resistance system are up-regulated, and fliE is down-regulated, by sdiA. Gene regulation by sdiA of E. coli is only partially dependent upon AHL.

Conclusions/significance: The genes of E. coli that respond to plasmid-based expression of sdiA are largely different than those that respond to chromosomal sdiA and/or AHL. This has significant implications for determining the true function of AHL detection by E. coli.

Show MeSH
Related in: MedlinePlus