Diversion of phagosome trafficking by pathogenic Rhodococcus equi depends on mycolic acid chain length.
Rhodococcus equi is a close relative of Mycobacterium spp. and a facultative intracellular pathogen which arrests phagosome maturation in macrophages before the late endocytic stage. We have screened a transposon mutant library of R. equi for mutants with decreased capability to prevent phagolysosome formation. This screen yielded a mutant in the gene for β-ketoacyl-(acyl carrier protein)-synthase A (KasA), a key enzyme of the long-chain mycolic acid synthesizing FAS-II system. The longest kasA mutant mycolic acid chains were 10 carbon units shorter than those of wild-type bacteria. Coating of non-pathogenic E. coli with purified wild-type trehalose dimycolate reduced phagolysosome formation substantially which was not the case with shorter kasA mutant-derived trehalose dimycolate. The mutant was moderately attenuated in macrophages and in a mouse infection model, but was fully cytotoxic.Whereas loss of KasA is lethal in mycobacteria, R. equi kasA mutant multiplication in broth was normal proving that long-chain mycolic acid compounds are not necessarily required for cellular integrity and viability of the bacteria that typically produce them. This study demonstrates a central role of mycolic acid chain length in diversion of trafficking by R. equi.
Institute for Cell Biology, University of Bonn, Bonn, Germany.
Tobias
T
Sydor
Kristine
K
von Bargen
Fong-Fu
FF
Hsu
Gitta
G
Huth
Otto
O
Holst
Jens
J
Wohlmann
Ulrike
U
Becken
Tobias
T
Dykstra
Kristina
K
Söhl
Buko
B
Lindner
John F
JF
Prescott
Ulrich E
UE
Schaible
Olaf
O
Utermöhlen
Albert
A
Haas
D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase / Q000235:genetics; D000193:Actinomycetales Infections / Q000276:immunology / Q000382:microbiology; D000818:Animals; D002460:Cell Line; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004195:Disease Models, Animal; D055786:Gene Knockout Techniques; D054884:Host-Pathogen Interactions; D008264:Macrophages / Q000382:microbiology*; D051379:Mice; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009171:Mycolic Acids / Q000378:metabolism*; D010588:Phagosomes / Q000382:microbiology*; D016929:Rhodococcus equi / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D017422:Sequence Analysis, DNA; D014774:Virulence
D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D009171:Mycolic Acids; D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase