Rab14 is critical for maintenance of Mycobacterium tuberculosis phagosome maturation arrest.
Mycobacterium tuberculosis arrests phagosomal maturation in infected macrophage, and, apart from health significance, provides a superb model system to dissect the phagolysosomal biogenesis pathway. Here, we demonstrate a critical role for the small GTPase Rab14 in maintaining mycobacterial phagosome maturation block. Four-dimensional microscopy showed that phagosomes containing live mycobacteria accumulated Rab14 following phagocytosis. The recruitment of Rab14 had strong functional consequence, as a knockdown of endogenous Rab14 by siRNA or overexpression of Rab14 dominant-negative mutants (Rab14S25N and Rab14N125I) released the maturation block and allowed phagosomes harboring live mycobacteria to progress into phagolysosomes. Conversely, overexpression of the wild-type Rab14 and the constitutively active mutant Rab14Q70L prevented phagosomes with dead mycobacteria from undergoing default maturation into phagolysosomal organelles. Mechanistic studies demonstrated a role for Rab14 in stimulating organellar fusion between phagosomes and early endosomes but not with late endosomes. Rab14 enables mycobacterial phagosomes to maintain early endosomal characteristics and avoid late endosomal/lysosomal degradative components.
Kyei
George B
GB
Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, Albuquerque, NM, USA.
Vergne
Isabelle
I
Chua
Jennifer
J
Roberts
Esteban
E
Harris
James
J
Junutula
Jagath R
JR
Deretic
Vojo
V
D000818:Animals; D002460:Cell Line; D011992:Endosomes / Q000502:physiology; D006801:Humans; D007425:Intracellular Membranes / Q000502:physiology; D008264:Macrophages / Q000382:microbiology* / Q000502:physiology; D008561:Membrane Fusion; D051379:Mice; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000378:metabolism / Q000502:physiology*; D010588:Phagosomes / Q000382:microbiology / Q000502:physiology*; D034741:RNA, Small Interfering / Q000235:genetics; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*
D034741:RNA, Small Interfering; D020691:rab GTP-Binding Proteins