A unique PE_PGRS protein inhibiting host cell cytosolic defenses and sustaining full virulence of Mycobacterium marinum in multiple hosts.
Despite intense research, PE_PGRS proteins still represent an intriguing aspect of mycobacterial pathogenesis. These cell surface proteins influence virulence in several pathogenic species, but their diverse and exact functions remain unclear. Herein, we focussed on a PE_PGRS member from Mycobacterium marinum, MMAR_0242, characterized by an extended and unique C-terminal domain. We demonstrate that an M. marinum mutant carrying a transposon insertion in MMAR_0242 is highly impaired in its ability to replicate in macrophages and amoebae, because of its inability to inhibit lysosomal fusion. As a consequence, this mutant failed to survive intracellularly as evidenced by a reduced number of cytosolic actin tail-forming bacteria and by quantitative electron microscopy, which mainly localized MMAR_0242::Tn within membrane-defined vacuoles. Functional complementation studies indicated that the C-terminus, but not the N-terminal PE_PGRS domain, is required for intracellular growth/survival. In line with these findings, disruption of MMAR_0242 resulted in a highly attenuated virulence phenotype in zebrafish embryos, characterized by restricted bacterial loads and a failure to produce granulomas. Furthermore, expression of MMAR_0242 in Mycobacterium smegmatis, a non-pathogenic species naturally deficient in PE_PGRS production, resulted in increased survival in amoebae with enhanced cytotoxic cell death and increased survival in infected mice with splenomegaly. Overall, these results indicate that MMAR_0242 is required for full virulence of M. marinum and sufficient to confer pathogenic properties to M. smegmatis.
Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS UMR 5235, case 107, Place Eugène Bataillon, 34095, Montpellier Cedex 05, France.
Vipul K
VK
Singh
Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS UMR 5235, case 107, Place Eugène Bataillon, 34095, Montpellier Cedex 05, France.
Laurence
L
Berry
Centre d'étude des Pathogènes et Biotechnologies pour la Santé (CPBS), CNRS FRE 3689, 1919 route de Mende, 34293, Montpellier, France.
Audrey
A
Bernut
Biochemistry Division, CSIR-Central Drug Research Institute, 226031, Lucknow, Uttar Pradesh, India.|IFTM University, Lodhipur Rajput, Delhi Road (NH-24) Moradabad, Uttar Pradesh, 244102, India.
Shubhra
S
Singh
INSERM U1058, Université de Montpellier and Department of Bacteriology-Virology, CHU de Montpellier, 34095, Montpellier, France.
Séverine
S
Carrère-Kremer
Centre d'étude des Pathogènes et Biotechnologies pour la Santé (CPBS), CNRS FRE 3689, 1919 route de Mende, 34293, Montpellier, France.
Albertus
A
Viljoen
Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS UMR 5235, case 107, Place Eugène Bataillon, 34095, Montpellier Cedex 05, France.
Laeticia
L
Alibaud
Institut Pasteur, Unité de Pathogénomique Mycobactérienne Intégrée, 25 rue du Dr. Roux, 75724, Paris, France.
Laleh
L
Majlessi
Institut Pasteur, Unité de Pathogénomique Mycobactérienne Intégrée, 25 rue du Dr. Roux, 75724, Paris, France.
Roland
R
Brosch
Biochemistry Division, CSIR-Central Drug Research Institute, 226031, Lucknow, Uttar Pradesh, India.
Vinita
V
Chaturvedi
Department of Medical Microbiology and Infection Control, VU University Medical Center, 1081 BT, Amsterdam, The Netherlands.
Jeroen
J
Geurtsen
Université Aix-Marseille, URMITE, UMR63, CNRS 7278, IRD 198, INSERM 1095, Marseille, France.
Michel
M
Drancourt
Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS UMR 5235, case 107, Place Eugène Bataillon, 34095, Montpellier Cedex 05, France. laurent.kremer@cpbs.cnrs.fr.|Centre d'étude des Pathogènes et Biotechnologies pour la Santé (CPBS), CNRS FRE 3689, 1919 route de Mende, 34293, Montpellier, France. laurent.kremer@cpbs.cnrs.fr.|INSERM, CPBS, 1919 route de Mende, Montpellier, France. laurent.kremer@cpbs.cnrs.fr.
Laurent
L
Kremer
D000656:Amoeba / Q000382:microbiology; D000818:Animals; D001426:Bacterial Proteins / Q000502:physiology*; D002460:Cell Line; D054884:Host-Pathogen Interactions; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D050296:Microbial Viability; D019910:Mycobacterium marinum / Q000472:pathogenicity / Q000502:physiology*; D020102:Mycobacterium smegmatis / Q000472:pathogenicity / Q000502:physiology; D014774:Virulence; D037521:Virulence Factors / Q000502:physiology
D001426:Bacterial Proteins; D037521:Virulence Factors