Global Profiling of PknG Interactions Using a Human Proteome Microarray Reveals Novel Connections with CypA

Area of Science:

• Microbiology
• Immunology
• Molecular Biology

Background:

• Mycobacterium tuberculosis (Mtb) serine/threonine kinase PknG is crucial for Mtb survival within host macrophages.
• The specific host proteins interacting with PknG and the molecular mechanisms remain largely uncharacterized.

Purpose of the Study:

• To globally identify host proteins interacting with Mtb PknG.
• To elucidate the functional consequences of PknG-host protein interactions on host inflammatory responses and Mtb pathogenesis.

Main Methods:

• Utilized a HuProt array to screen for PknG-interacting host proteins.
• Validated PknG-CypA interaction using in vitro and in vivo methods.
• Assessed the impact of PknG on CypA protein levels, inflammatory pathways (NF-κB, ERK1/2), and Mtb survival in macrophages.

Main Results:

• Identified 125 host protein interactors of PknG, including cyclophilin A (CypA).
• Demonstrated that PknG phosphorylates and reduces CypA protein levels, leading to suppressed NF-κB and ERK1/2 activation.
• Showed that PknG overexpression reduces cytokine levels and enhances Mycobacterium smegmatis (Msm) survival in macrophages.

Conclusions:

• PknG interacts with numerous host proteins, notably CypA, modulating host inflammatory responses.
• PknG-mediated downregulation of CypA and associated inflammatory pathways is a key mechanism for Mtb survival in macrophages.
• The identified PknG interactors provide a resource for further investigation into Mtb-host interactions.