title: Laribacter hongkongensis anaerobic adaptation mediated by arginine metabolism is controlled by the cooperation of FNR and ArgR.
abstract: Laribacter hongkongensis is a fish-borne pathogen associated with invasive infections and gastroenteritis. Its adaptive mechanisms to oxygen-limiting conditions in various environmental niches remain unclear. In this study, we compared the transcriptional profiles of L. hongkongensis under aerobic and anaerobic conditions using RNA-sequencing. Expression of genes involved in arginine metabolism significantly increased under anoxic conditions. Arginine was exploited as the sole energy source in L. hongkongensis for anaerobic respiration via the arginine catabolism pathway: specifically via the arginine deiminase (ADI) pathway. A transcriptional regulator FNR was identified to coordinate anaerobic metabolism by tightly regulating the expression of arginine metabolism genes. FNR executed its regulatory function by binding to FNR boxes in arc operons promoters. Survival of isogenic fnr mutant in macrophages decreased significantly when compared with wild-type; and expression level of fnr increased 8 h post-infection. Remarkably, FNR directly interacted with ArgR, another regulator that influences the biological fitness and intracellular survival of L. hongkongensis by regulating arginine metabolism genes. Our results demonstrated that FNR and ArgR work in coordination to respond to oxygen changes in both extracellular and intracellular environments, by finely regulating the ADI pathway and arginine anabolism pathways, thereby optimizing bacterial fitness in various environmental niches.
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.|Department of Microbiology, The University of Hong Kong, Hong Kong.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Xiong
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong.
authors.forename: Ying
authors.initials: Y
authors.lastname: Yang
authors.affiliation: School of Biology and Engineering, Guizhou Medical University, Guizhou, China.
authors.forename: Yuan-Nong
authors.initials: YN
authors.lastname: Ye
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong.|Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong.|State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong.|Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong.
authors.forename: Jade L L
authors.initials: JL
authors.lastname: Teng
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong.
authors.forename: Elaine
authors.initials: E
authors.lastname: Chan
authors.affiliation: Applied Oral Sciences, Faculty of Dentistry, The University of Hong Kong, Hong Kong.
authors.forename: Rory M
authors.initials: RM
authors.lastname: Watt
authors.affiliation: Center of Bioinformatics, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, China.
authors.forename: Feng-Biao
authors.initials: FB
authors.lastname: Guo
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong.|Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong.|State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong.|Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong.|Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The University of Hong Kong, Hong Kong.
authors.forename: Susanna K P
authors.initials: SK
authors.lastname: Lau
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.|Department of Microbiology, The University of Hong Kong, Hong Kong.|Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong.|State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong.|Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong.|Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The University of Hong Kong, Hong Kong.
authors.forename: Patrick C Y
authors.initials: PC
authors.lastname: Woo
mesh_terms: D000064:Acclimatization; D000222:Adaptation, Physiological; D000693:Anaerobiosis; D001120:Arginine / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D020562:Betaproteobacteria / Q000235:genetics / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D006867:Hydrolases / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D009876:Operon; D011401:Promoter Regions, Genetic
chemical_list: D001426:Bacterial Proteins; D007506:Iron-Sulfur Proteins; D001120:Arginine; D006867:Hydrolases; C019723:arginine deiminase