Biology subjects

Jaramillo-Riveri, S.

Publications and source records attributed to Jaramillo-Riveri, S..

2 recordsLinked to original sources

bioRxiv2021

Growth-dependent heterogeneity in the DNA damage response in Escherichia coli

In natural environments bacteria are frequently exposed to sub-lethal levels of DNA damage which leads to the induction of a stress response (the SOS response in Escherichia coli). Natural environments also vary in nutrient availability, resulting in distinct physiological changes in bacteria which may have direct implications on their capacity to repair their chromosomes. Here, we evaluated the impact of varying the nutrient availability on the expression of the SOS response induced by chronic sub-lethal DNA damage in E. coli. The expression of the SOS regulon was found to be highly heterogeneous at the single-cell level in all growth conditions. Surprisingly, we observed a larger fraction of high SOS-induced cells in slow growth as compared with fast growth, despite a higher rate of SOS induction in fast growth. This counter-intuitive result can be explained by the dynamic balance between the rate of SOS induction and the division rates of cells exposed to DNA damage. Taken together, our data illustrates how cell division and physiology come together to produce growth-dependent heterogeneity in the DNA damage response.

cell biology↗

bioRxiv2017

Quantification of very low-abundant proteins in bacteria using the HaloTag and epi-fluorescence microscopy

Cell biology is increasingly dependent on quantitative methods resulting in the need for microscopic labelling technologies that are highly sensitive and specific. Whilst the use of fluorescent proteins has led to major advances, they also suffer from their relatively low brightness and photo-stability, making the detection of very low abundance proteins using fluorescent protein-based methods challenging. Here, we characterize the use of the self-labelling protein tag called HaloTag, in conjunction with an organic fluorescent dye, to label and accurately count endogenous proteins present in very low numbers (<7) in individual Escherichia coli cells. This procedure can be used to detect single molecules in fixed cells with conventional epifluorescence illumination and a standard microscope. We show that the detection efficiency of proteins labelled with the HaloTag is [≥]80%, which is on par or better than previous techniques. Therefore, this method offers a simple and attractive alternative to current procedures to detect low abundance molecules.

systems biology↗