Project description:The chemically mutagenized Escherichia coli strain AS19 was isolated on the basis of its enhanced sensitivity to different antibiotics, in particular to actinomycin. The strain was later modified to study rRNA modifications that confer antibiotic resistance. Here, we present the genome sequence of the variant E. coli AS19-RrmA.
Project description:Defining the cellular factors that drive growth rate and proteome composition is essential for understanding and manipulating cellular systems. In bacteria, ribosome concentration is known to be a constraining factor of cell growth rate, while gene concentration is usually assumed not to be limiting. Here, using single-molecule tracking, quantitative single-cell microscopy, and modeling, we show that genome dilution in Escherichia coli cells arrested for DNA replication results in a decrease in the concentration of active RNA polymerases and ribosomes. The resulting sub-linear scaling of total active RNA polymerases and ribosomes with cell size leads to sub-exponential growth, even within physiological cell sizes. Cell growth rate scales proportionally with the total number of active ribosomes in a DNA concentration-dependent manner. Tandem-mass-tag mass spectrometry experiments further revealed that a decrease in DNA-to-cell-volume ratio also incrementally remodels proteome composition with cell size. Altogether, our findings indicate that genome concentration is an important driver of exponential cell growth and a global modulator of proteome composition in E. coli. Comparison with studies on eukaryotic cells suggests DNA concentration-dependent scaling principles of gene expression across domains of life.
