Activation of Rho and Rab GTPases dissociates Brucella abortus internalization from intracellular trafficking.
Brucella abortus is an intracellular pathogen that relies on unconventional virulence factors to infect hosts. In non-professional phagocytes, Rho GTPases-activation by the Escherichia coli cytotoxic necrotizing factor (CNF) promoted massive Brucella entrance by membrane ruffling, a mechanism that differs from the common mode of entrance used by this bacterium in non-treated cells. Cytotoxic necrotizing factor treatment, however, did not alter the intracellular route followed by the wild type or non-virulent defined mutants. In contrast, expression of a constitutively active Rab5Q79L GTPase did not alter cell-invasion by Brucella but hampered its ability to reach the endoplasmic reticulum. The CNF-induced Brucella super-infection did not reduce the ability of host cells to synthesize DNA and progress through the cell cycle. Furthermore, CNF-treatment increased the isolation of Brucella-containing compartments by a factor of 15. These results demonstrate that in non-professional phagocytic cells, Brucella manipulates two different sets of GTPases during its biogenesis, being internalization and intracellular trafficking two consecutive but independent processes. Besides, CNF-induced super-infection demonstrates that Brucella does not interfere with crucial cellular processes and has shown its potential as tool to characterize the intracellular compartments occupied by this bacterium.
D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism; D002003:Brucella abortus / Q000502:physiology*; D002006:Brucellosis / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003603:Cytotoxins / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D029968:Escherichia coli Proteins; D006801:Humans; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D010587:Phagocytosis; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
D001427:Bacterial Toxins; D003603:Cytotoxins; D029968:Escherichia coli Proteins; C060296:cytotoxic necrotizing factor type 1; D004247:DNA; D020691:rab GTP-Binding Proteins; D020741:rho GTP-Binding Proteins