An atypical riboflavin pathway is essential for Brucella abortus virulence.
Brucellosis is a worldwide zoonosis that affects livestock and humans and is caused by closely related Brucella spp., which are adapted to intracellular life within cells of a large variety of mammals. Brucella can be considered a furtive pathogen that infects professional and non-professional phagocytes. In these cells Brucella survives in a replicative niche, which is characterized for having a very low oxygen tension and being deprived from nutrients such as amino acids and vitamins. Among these vitamins, we have focused on riboflavin (vitamin B2). Flavin metabolism has been barely implicated in bacterial virulence. We have recently described that Brucella and other Rhizobiales bear an atypical riboflavin metabolic pathway. In the present work we analyze the role of the flavin metabolism on Brucella virulence. Mutants on the two lumazine synthases (LS) isoenzymes RibH1 and RibH2 and a double RibH mutant were generated. These mutants and different complemented strains were tested for viability and virulence in cells and in mice. In this fashion we have established that at least one LS must be present for B. abortus survival and that RibH2 and not RibH1 is essential for intracellular survival due to its LS activity in vivo. In summary, we show that riboflavin biosynthesis is essential for Brucella survival inside cells or in mice. These results highlight the potential use of flavin biosynthetic pathway enzymes as targets for the chemotherapy of brucellosis.
Bonomi
Hernán Ruy
HR
Fundación Instituto Leloir-CONICET, Buenos Aires, Argentina.
Marchesini
María Inés
MI
Klinke
Sebastián
S
Ugalde
Juan E
JE
Zylberman
Vanesa
V
Ugalde
Rodolfo A
RA
Comerci
Diego J
DJ
Goldbaum
Fernando Alberto
FA
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D053898:Biosynthetic Pathways; D015153:Blotting, Western; D002003:Brucella abortus / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D002006:Brucellosis / Q000382:microbiology; D002460:Cell Line; D005260:Female; D005816:Genetic Complementation Test; D006367:HeLa Cells; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D051907:Lysosomal Membrane Proteins / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D050296:Microbial Viability; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D012256:Riboflavin / Q000096:biosynthesis*; D014774:Virulence; D052118:Lysosomal-Associated Membrane Protein 1
D001426:Bacterial Proteins; D007527:Isoenzymes; D051907:Lysosomal Membrane Proteins; D009097:Multienzyme Complexes; D012256:Riboflavin; C052255:Lamp1 protein, mouse; D052118:Lysosomal-Associated Membrane Protein 1; C044822:6,7-dimethyl-8-ribityllumazine synthase