Regulation of Rab5 function during phagocytosis of live Pseudomonas aeruginosa in macrophages

Infect Immun. 2013 Jul;81(7):2426-36. doi: 10.1128/IAI.00387-13. Epub 2013 Apr 29.


Pseudomonas aeruginosa, a Gram-negative opportunistic human pathogen, is a frequent cause of severe hospital-acquired infections. Effectors produced by the type III secretion system disrupt mammalian cell membrane trafficking and signaling and are integral to the establishment of P. aeruginosa infection. One of these effectors, ExoS, ADP-ribosylates several host cell proteins, including Ras and Rab GTPases. In this study, we demonstrated that Rab5 plays a critical role during early stages of P. aeruginosa invasion of J774-Eclone macrophages. We showed that live, but not heat-inactivated, P. aeruginosa inhibited phagocytosis and that this occurred in conjunction with downregulation of Rab5 activity. Inactivation of Rab5 was dependent on ExoS ADP-ribosyltransferase activity, and in J744-Eclone cells, ExoS ADP-ribosyltransferase activity caused a more severe inhibition of phagocytosis than ExoS Rho GTPase activity. Furthermore, we found that expression of Rin1, a Rab5 guanine exchange factor, but not Rabex5 and Rap6, partially reversed the inactivation of Rab5 during invasion of live P. aeruginosa. These studies provide evidence that live P. aeruginosa cells are able to influence their rate of phagocytosis in macrophages by directly regulating activation of Rab5.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP Ribose Transferases / genetics
  • ADP Ribose Transferases / metabolism*
  • Animals
  • Bacterial Toxins / genetics
  • Bacterial Toxins / metabolism*
  • Cell Line
  • Enzyme Activation
  • Exotoxins / genetics
  • Exotoxins / metabolism
  • Gene Expression Regulation, Enzymologic
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Guanine Nucleotide Exchange Factors / genetics
  • Guanine Nucleotide Exchange Factors / metabolism
  • Intracellular Signaling Peptides and Proteins
  • Macrophages / enzymology
  • Macrophages / microbiology*
  • Mice
  • Phagocytosis*
  • Proteolysis
  • Pseudomonas Infections / microbiology
  • Pseudomonas aeruginosa / genetics
  • Pseudomonas aeruginosa / metabolism
  • Pseudomonas aeruginosa / pathogenicity*
  • RNA Interference
  • rab GTP-Binding Proteins / genetics
  • rab GTP-Binding Proteins / metabolism
  • rab5 GTP-Binding Proteins / genetics
  • rab5 GTP-Binding Proteins / metabolism*


  • Bacterial Toxins
  • Exotoxins
  • Guanine Nucleotide Exchange Factors
  • Intracellular Signaling Peptides and Proteins
  • RabGEF1 protein, mouse
  • Rin1 protein, mouse
  • Green Fluorescent Proteins
  • ADP Ribose Transferases
  • exoenzyme S
  • rab GTP-Binding Proteins
  • rab5 GTP-Binding Proteins