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Gene regulation by H-NS as a function of growth conditions depends on chromosomal position in Escherichia coli.

Brambilla E, Sclavi B - G3 (Bethesda) (2015)

Bottom Line: Cellular adaptation to changing environmental conditions requires the coordinated regulation of expression of large sets of genes by global regulatory factors such as nucleoid associated proteins.Our results show that the activity of the Phns promoter depends on whether it is placed within the AT-rich regions of the genome that are known to be bound preferentially by H-NS.Genomic position can thus play a significant role in the adaptation of the cells to environmental changes, providing a fitness advantage that can explain the selection of a gene's position during evolution.

View Article: PubMed Central - PubMed

Affiliation: LBPA, UMR 8113 du CNRS, Ecole Normale Supérieure de Cachan, Cachan, France School of Engineering and Science, Jacobs University Bremen, Bremen, Germany.

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The difference in YFP concentration in exponential phase at two different growth rates can be explained for most positions by the change in gene copy number. YFP concentration was measured in mid exponential phase for the six chromosomal insertions at two different doubling times as a function of chromosomal position (0 for the origin of replication, 1 for the terminus). Data are the average of three independent plate reader experiments; the error bar corresponds to the SEM. The dotted line is the theoretical dependence of protein concentration as expected by the difference in gene copy number (Cooper-Helmstetter relation) for each growth rate (Cooper and Helmstetter 1968) (see the section Materials and Methods). The protein concentration for the LT strain is lower than what would be expected as a consequence of gene dosage, both at fast and at slow growth rates (glu04CAA05 and CAA02, respectively, at 30°). At slow growth, the concentration in the RO strain also deviates from the theoretical expectation. LM, left medium; LO, left origin; LT, left terminus; RM, right medium; RO, right origin; RT, right terminus; YFP, yellow fluorescent protein.
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fig3: The difference in YFP concentration in exponential phase at two different growth rates can be explained for most positions by the change in gene copy number. YFP concentration was measured in mid exponential phase for the six chromosomal insertions at two different doubling times as a function of chromosomal position (0 for the origin of replication, 1 for the terminus). Data are the average of three independent plate reader experiments; the error bar corresponds to the SEM. The dotted line is the theoretical dependence of protein concentration as expected by the difference in gene copy number (Cooper-Helmstetter relation) for each growth rate (Cooper and Helmstetter 1968) (see the section Materials and Methods). The protein concentration for the LT strain is lower than what would be expected as a consequence of gene dosage, both at fast and at slow growth rates (glu04CAA05 and CAA02, respectively, at 30°). At slow growth, the concentration in the RO strain also deviates from the theoretical expectation. LM, left medium; LO, left origin; LT, left terminus; RM, right medium; RO, right origin; RT, right terminus; YFP, yellow fluorescent protein.

Mentions: For most of the sites, comparison of YFP concentration as a function of genomic position in exponential phase shows a difference between the sites that can be explained by the differences in gene copy number expected from the DNA replication process (Figure 3). Interestingly, there is also a difference in gene expression between the sites that are equidistant from the origin, notably between left terminus (LT) and right terminus (RT) and right origin (RO) and left origin (LO). The latter difference becomes evident especially at slow growth and upon entry into stationary phase (Figure 3 and Figure 4).


Gene regulation by H-NS as a function of growth conditions depends on chromosomal position in Escherichia coli.

Brambilla E, Sclavi B - G3 (Bethesda) (2015)

The difference in YFP concentration in exponential phase at two different growth rates can be explained for most positions by the change in gene copy number. YFP concentration was measured in mid exponential phase for the six chromosomal insertions at two different doubling times as a function of chromosomal position (0 for the origin of replication, 1 for the terminus). Data are the average of three independent plate reader experiments; the error bar corresponds to the SEM. The dotted line is the theoretical dependence of protein concentration as expected by the difference in gene copy number (Cooper-Helmstetter relation) for each growth rate (Cooper and Helmstetter 1968) (see the section Materials and Methods). The protein concentration for the LT strain is lower than what would be expected as a consequence of gene dosage, both at fast and at slow growth rates (glu04CAA05 and CAA02, respectively, at 30°). At slow growth, the concentration in the RO strain also deviates from the theoretical expectation. LM, left medium; LO, left origin; LT, left terminus; RM, right medium; RO, right origin; RT, right terminus; YFP, yellow fluorescent protein.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390576&req=5

fig3: The difference in YFP concentration in exponential phase at two different growth rates can be explained for most positions by the change in gene copy number. YFP concentration was measured in mid exponential phase for the six chromosomal insertions at two different doubling times as a function of chromosomal position (0 for the origin of replication, 1 for the terminus). Data are the average of three independent plate reader experiments; the error bar corresponds to the SEM. The dotted line is the theoretical dependence of protein concentration as expected by the difference in gene copy number (Cooper-Helmstetter relation) for each growth rate (Cooper and Helmstetter 1968) (see the section Materials and Methods). The protein concentration for the LT strain is lower than what would be expected as a consequence of gene dosage, both at fast and at slow growth rates (glu04CAA05 and CAA02, respectively, at 30°). At slow growth, the concentration in the RO strain also deviates from the theoretical expectation. LM, left medium; LO, left origin; LT, left terminus; RM, right medium; RO, right origin; RT, right terminus; YFP, yellow fluorescent protein.
Mentions: For most of the sites, comparison of YFP concentration as a function of genomic position in exponential phase shows a difference between the sites that can be explained by the differences in gene copy number expected from the DNA replication process (Figure 3). Interestingly, there is also a difference in gene expression between the sites that are equidistant from the origin, notably between left terminus (LT) and right terminus (RT) and right origin (RO) and left origin (LO). The latter difference becomes evident especially at slow growth and upon entry into stationary phase (Figure 3 and Figure 4).

Bottom Line: Cellular adaptation to changing environmental conditions requires the coordinated regulation of expression of large sets of genes by global regulatory factors such as nucleoid associated proteins.Our results show that the activity of the Phns promoter depends on whether it is placed within the AT-rich regions of the genome that are known to be bound preferentially by H-NS.Genomic position can thus play a significant role in the adaptation of the cells to environmental changes, providing a fitness advantage that can explain the selection of a gene's position during evolution.

View Article: PubMed Central - PubMed

Affiliation: LBPA, UMR 8113 du CNRS, Ecole Normale Supérieure de Cachan, Cachan, France School of Engineering and Science, Jacobs University Bremen, Bremen, Germany.

Show MeSH
Related in: MedlinePlus