@article{mbs:/content/journal/micro/10.1099/mic.0.2007/012021-0, author = "White-Ziegler, Christine A. and Um, Suzin and Pérez, Natalie M. and Berns, Abby L. and Malhowski, Amy J. and Young, Sarah", title = "Low temperature (23 °C) increases expression of biofilm-, cold-shock- and RpoS-dependent genes in Escherichia coli K-12", journal= "Microbiology", year = "2008", volume = "154", number = "1", pages = "148-166", doi = "https://doi.org/10.1099/mic.0.2007/012021-0", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.2007/012021-0", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", keywords = "COGs, clusters of orthologous groups of proteins", keywords = "qRT-PCR, quantitative real-time RT-PCR", abstract = "Temperature serves as a cue to regulate gene expression in Escherichia coli and other bacteria. Using DNA microarrays, we identified 297 genes whose expression is increased at 23 °C compared to 37 °C in E. coli K-12. Of these genes, 122 are RpoS-controlled, confirming genome-wide the model that low temperature serves as a primary cue to trigger the general stress response. Several genes expressed at 23 °C overlap with the cold-shock response, suggesting that strategies used to adapt to sudden shifts in temperature also mediate long-term growth at 23 °C. Another category of genes more highly expressed at 23 °C are associated with biofilm development, implicating temperature as an important cue influencing this developmental pathway. In a candidate set of genes tested, the biofilm genes (adrA, bolA, mlrA, nhaR, csgA, yceP/bssS) and cold-shock genes (otsA, yceP/bssS) were found to be RpoS- and DsrA-dependent for their transcription at 23 °C. In contrast, transcription of three genes (ycgZ, dps and ymgB) was either partially or fully independent of these regulators, signifying there is an alternative thermoregulatory mechanism(s) that increases gene expression at 23 °C. Increased expression at 23 °C compared to 37 °C is retained in various media tested for most of the genes, supporting the relative importance of this cue in adaptation to changing environments. Both the RpoS-dependent gene otsA and the RpoS-independent gene ymgB demonstrated increased expression levels within 1 h after a shift from 37 to 23 °C, indicating a rapid response to this environmental cue. Despite changes in gene expression for many RpoS-dependent genes, experiments assessing growth rate at 23 °C and viability at 4 °C did not demonstrate significant impairment in rpoS : : Tn10 or dsrA : : cat mutant strains in comparison to the wild-type strain. Biofilm formation was favoured at low temperature and is moderately impaired in both the rpoS : : Tn10 and dsrA : : cat mutants at 23 °C, suggesting genes controlled by these regulators play a role necessary for optimal biofilm formation at 23 °C. Taken together, our data demonstrate that a large number of genes are increased in expression at 23 °C to globally respond to this environmental change and that at least two thermoregulatory pathways are involved in co-ordinating this response – the RpoS/DsrA pathway and an alternative thermoregulatory pathway, independent of these regulators.", }