Update of thermotolerant genes essential for survival at a critical high temperature in Escherichia coli

Previous screening of a single-gene knockout library consisting of 3,908 disrupted-mutant strains allowed us to identify 51 thermotolerant genes that are essential for survival at a critical high temperature (CHT) in Escherichia coli [Murata M, Fujimoto H, Nishimura K, Charoensuk K, Nagamitsu H, Raina S, Kosaka T, Oshima T, Ogasawara N, Yamada M (2011) PLoS ONE 6: e20063]. In this study, we identified another 21 thermotolerant genes. E. coli thus has 72 thermotolerant genes in total. The genes are classified into 8 groups: genes for energy metabolism, outer membrane organization, DNA double-strand break repair, tRNA modification, protein quality control, translation control, cell division and transporters. This classification and physiological analysis indicate the existence of fundamental strategies for survival at a CHT, which seems to exclude most of the heat shock responses.