AUTHOR=Cheng Changyong , Liu Feng , Jin Haobo , Xu Xiangfei , Xu Jiali , Deng Simin , Xia Jing , Han Yue , Lei Lei , Zhang Xian , Song Houhui TITLE=The DegU Orphan Response Regulator Contributes to Heat Stress Resistance in Listeria monocytogenes JOURNAL=Frontiers in Cellular and Infection Microbiology VOLUME=11 YEAR=2021 URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2021.761335 DOI=10.3389/fcimb.2021.761335 ISSN=2235-2988 ABSTRACT=

Listeria monocytogenes is more heat-resistant than most other non-spore-forming foodborne pathogens, posing a severe threat to food safety and human health, particularly during chilled food processing. The DegU orphan response regulator is known to control heat resistance in L. monocytogenes; however, the underlying regulatory mechanism is poorly understood. Here, we show that DegU contributes to L. monocytogenes exponential growth under mild heat-shock stress. We further demonstrate that DegU directly senses heat stress through autoregulation and upregulates the hrcA-grpE-dnaK-dnaJ operon, leading to increased production of heat-shock proteins. We also show that DegU can directly regulate the expression of the hrcA-grpE-dnaK-dnaJ operon. In conclusion, our results shed light on the regulatory mechanisms underlying how DegU directly activates the hrcA-grpE-dnaK-dnaJ operon, thereby regulating heat resistance in L. monocytogenes.