title: Mycobacterium tuberculosis Ser/Thr protein kinase B mediates an oxygen-dependent replication switch.
abstract: The majority of Mycobacterium tuberculosis (Mtb) infections are clinically latent, characterized by drug tolerance and little or no bacterial replication. Low oxygen tension is a major host factor inducing bacteriostasis, but the molecular mechanisms driving oxygen-dependent replication are poorly understood. Here, we tested the role of serine/threonine phosphorylation in the Mtb response to altered oxygen status, using an in vitro model of latency (hypoxia) and reactivation (reaeration). Broad kinase inhibition compromised survival of Mtb in reaeration. Activity-based protein profiling and genetic mutation identified PknB as the kinase critical for surviving hypoxia. Mtb replication was highly sensitive to changes in PknB levels in aerated culture, and even more so in hypoxia. A mutant overexpressing PknB specifically in hypoxia showed a 10-fold loss in viability and gross morphological defects in low oxygen conditions. In contrast, chemically reducing PknB activity during hypoxia specifically compromised resumption of growth during reaeration. These data support a model in which PknB activity is reduced to achieve bacteriostasis, and elevated when replication resumes. Together, these data show that phosphosignaling controls replicative transitions associated with latency and reactivation, that PknB is a major regulator of these transitions, and that PknB could provide a highly vulnerable therapeutic target at every step of the Mtb life cycle-active disease, latency, and reactivation.
authors.affiliation: Seattle Biomedical Research Institute, Seattle, Washington, United States of America ; Department of Global Health, University of Washington, Seattle, Washington, United States of America.
authors.forename: Corrie
authors.initials: C
authors.lastname: Ortega
authors.affiliation: Seattle Biomedical Research Institute, Seattle, Washington, United States of America.
authors.forename: Reiling
authors.initials: R
authors.lastname: Liao
authors.affiliation: Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America.
authors.forename: Lindsey N
authors.initials: LN
authors.lastname: Anderson
authors.affiliation: Seattle Biomedical Research Institute, Seattle, Washington, United States of America.
authors.forename: Tige
authors.initials: T
authors.lastname: Rustad
authors.affiliation: Seattle Biomedical Research Institute, Seattle, Washington, United States of America.
authors.forename: Anja R
authors.initials: AR
authors.lastname: Ollodart
authors.affiliation: Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America.
authors.forename: Aaron T
authors.initials: AT
authors.lastname: Wright
authors.affiliation: Seattle Biomedical Research Institute, Seattle, Washington, United States of America ; Department of Global Health, University of Washington, Seattle, Washington, United States of America.
authors.forename: David R
authors.initials: DR
authors.lastname: Sherman
authors.affiliation: Seattle Biomedical Research Institute, Seattle, Washington, United States of America ; Department of Global Health, University of Washington, Seattle, Washington, United States of America.
authors.forename: Christoph
authors.initials: C
authors.lastname: Grundner
mesh_terms: D000693:Anaerobiosis; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002227:Carbazoles / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial; D026121:Indole Alkaloids / Q000494:pharmacology; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D010100:Oxygen / Q000378:metabolism* / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction; D013912:Threonine / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002227:Carbazoles; D026121:Indole Alkaloids; D047428:Protein Kinase Inhibitors; D013912:Threonine; D012694:Serine; C049985:staurosporine aglycone; D051057:Proto-Oncogene Proteins c-akt; D010100:Oxygen