The Bacterial Second Messenger Cyclic di-GMP Regulates Brucella Pathogenesis and Leads to Altered Host Immune Response.
Brucella species are facultative intracellular bacteria that cause brucellosis, a chronic debilitating disease significantly impacting global health and prosperity. Much remains to be learned about how Brucella spp. succeed in sabotaging immune host cells and how Brucella spp. respond to environmental challenges. Multiple types of bacteria employ the prokaryotic second messenger cyclic di-GMP (c-di-GMP) to coordinate responses to shifting environments. To determine the role of c-di-GMP in Brucella physiology and in shaping host-Brucella interactions, we utilized c-di-GMP regulatory enzyme deletion mutants. Our results show that a ΔbpdA phosphodiesterase mutant producing excess c-di-GMP displays marked attenuation in vitro and in vivo during later infections. Although c-di-GMP is known to stimulate the innate sensor STING, surprisingly, the ΔbpdA mutant induced a weaker host immune response than did wild-type Brucella or the low-c-di-GMP guanylate cyclase ΔcgsB mutant. Proteomics analysis revealed that c-di-GMP regulates several processes critical for virulence, including cell wall and biofilm formation, nutrient acquisition, and the type IV secretion system. Finally, ΔbpdA mutants exhibited altered morphology and were hypersensitive to nutrient-limiting conditions. In summary, our results indicate a vital role for c-di-GMP in allowing Brucella to successfully navigate stressful and shifting environments to establish intracellular infection.
Cellular and Molecular Pathology Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA mkhan23@wisc.edu.
Mike
M
Khan
Department of Pathobiological Sciences, University of Wisconsin-Madison School of Veterinary Medicine, Madison, Wisconsin, USA.
Jerome S
JS
Harms
Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte-Minas Gerais, Brazil.
Fernanda M
FM
Marim
Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
Leah
L
Armon
Department of Pediatrics, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA.
Cherisse L
CL
Hall
Department of Pediatrics, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA.
Yi-Ping
YP
Liu
Department of Bacteriology, Kimron Veterinary Institute, Beit Dagan, Israel.
Menachem
M
Banai
Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte-Minas Gerais, Brazil.
Sergio C
SC
Oliveira
Department of Pathobiological Sciences, University of Wisconsin-Madison School of Veterinary Medicine, Madison, Wisconsin, USA.
Gary A
GA
Splitter
Department of Pediatrics, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA.
Judith A
JA
Smith
D000222:Adaptation, Physiological; D000818:Animals; D018441:Biofilms; D002002:Brucella / Q000378:metabolism / Q000472:pathogenicity* / Q000648:ultrastructure; D002006:Brucellosis / Q000382:microbiology* / Q000473:pathology; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D056084:Genetic Fitness; D008264:Macrophages / Q000378:metabolism / Q000382:microbiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009154:Mutation; D000069319:Type IV Secretion Systems; D014774:Virulence; D000099197:STING Protein
D006152:Cyclic GMP; D008565:Membrane Proteins; D000069319:Type IV Secretion Systems; C530855:Sting1 protein, mouse; D000099197:STING Protein; C062025:bis(3',5')-cyclic diguanylic acid
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