Mycobacterial protein tyrosine kinase, PtkA phosphorylates PtpA at tyrosine residues and the mechanism is stalled by the novel series of inhibitors

Exploring the role of the protein tyrosine kinase a (PtkA) in mycobacterial intracellular survival

Mycobacterium tuberculosis (Mtb) continues to define new paradigms of host-pathogen interaction. There are several host proteins known which are regulated by Mtb infection. The proteins which regulate host biological processes like apoptosis, cell processes, stress proteins, metabolic enzymes, etc. are targeted by the pathogens. Mtb proteins interact directly or indirectly with host proteins and play an important role in their persistence and intracellular growth. Mtb is an intracellular pathogen. It remains dormant for years within the host without activating its immune system. Mtb Protein tyrosine kinase (PtkA) regulates host anti-apoptotic protein, metabolic enzymes, and several other proteins that are involved in stress regulation, cell proliferation, protein folding, DNA repair, etc. PtkA regulates other mycobacterial proteins and plays an important role in its growth and survival. Here we summarized the current knowledge of PtkA and reviewed its role in mycobacterial intracellular survival as it regulates several other mycobacterial proteins and host proteins. PtkA regulates PtpA secretion which is essential for mycobacterial virulence and could be used as an attractive drug target.

Protein Tyrosine and Serine/Threonine Phosphorylation in Oral Bacterial Dysbiosis and Bacteria-Host Interaction

The human oral cavity harbors approximately 1,000 microbial species, and dysbiosis of the microflora and imbalanced microbiota-host interactions drive many oral diseases, such as dental caries and periodontal disease. Oral microbiota homeostasis is critical for systemic health. Over the last two decades, bacterial protein phosphorylation systems have been extensively studied, providing mounting evidence of the pivotal role of tyrosine and serine/threonine phosphorylation in oral bacterial dysbiosis and bacteria-host interactions. Ongoing investigations aim to discover novel kinases and phosphatases and to understand the mechanism by which these phosphorylation events regulate the pathogenicity of oral bacteria. Here, we summarize the structures of bacterial tyrosine and serine/threonine kinases and phosphatases and discuss the roles of tyrosine and serine/threonine phosphorylation systems in Porphyromonas gingivalis and Streptococcus mutans, emphasizing their involvement in bacterial metabolism and virulence, community development, and bacteria-host interactions.

Phosphoproteomics of Mycobacterium-host interaction and inspirations for novel measures against tuberculosis

Tuberculosis caused by Mycobacterium tuberculosis (Mtb) remains a tremendous global public health concern. Deciphering the biology of the pathogen and its interaction with host can inspire new measures against tuberculosis. Phosphorylation plays versatile and important role in the pathogen and host physiology, such as virulence, signaling and immune response. Proteome-wide phosphorylation of Mtb and its infected host cells, namely phosphoproteome, can inform the post-translational modification of the interaction network between the pathogen and the host, key targets for novel antibiotics. We summarized the phosphoproteome of Mtb, as well as the host, focusing on potential application for new measures against tuberculosis.

Host Cell Targets of Released Lipid and Secreted Protein Effectors of Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) is a very successful pathogen, strictly adapted to humans and the cause of tuberculosis. Its success is associated with its ability to inhibit host cell intrinsic immune responses by using an arsenal of virulence factors of different nature. It has evolved to synthesize a series of complex lipids which form an outer membrane and may also be released to enter host cell membranes. In addition, secreted protein effectors of Mtb are entering the host cell cytosol to interact with host cell proteins. We briefly discuss the current model, involving the ESX-1 type seven secretion system and the Mtb lipid phthiocerol dimycoserosate (PDIM), of how Mtb creates pores in the phagosomal membrane to allow Mtb proteins to access to the host cell cytosol. We provide an exhaustive list of Mtb secreted proteins that have effector functions. They modify (mostly inhibit but sometimes activate) host cell pathways such as: phagosome maturation, cell death, cytokine response, xenophagy, reactive oxygen species (ROS) response via NADPH oxidase 2 (NOX2), nitric oxide (NO) response via NO Synthase 2 (NOS2) and antigen presentation via MHC class I and class II molecules. We discuss the host cell targets for each lipid and protein effector and the importance of the Mtb effector for virulence of the bacterium.

ATP synthase, an essential enzyme in growth and multiplication is modulated by protein tyrosine phosphatase in Mycobacterium tuberculosis H37Ra

Mycobacterium tuberculosis (Mtb) protein tyrosine phosphatase (PtpA) has so far been known to control intracellular survival of mycobacteria; whereas the ATP synthase which is essential for mycobacterial growth has recently been contemplated in developing a breakthrough anti-TB drug, diarylquinoline. Since both of these enzymes have been established as validated drug targets; we report a robust and functional relationship between these two enzymes through a series of experiments using Mtb H37Ra. In the present study we report that the mycobacterial ATP synthase alpha subunit is regulated by PtpA. We generated gene knock-out for the enzyme PtpA and subjected to determine the mycobacterial replication and the proteome profile of wild type, mutant (ΔptpA) and complemented (ΔptpA:ptpA) strains of Mtb H37Ra. A substantial amount of decrease in the protein level of ATP synthase alpha subunit (AtpA) in case of mutant H37Ra was observed, while the levels of the enzyme were either increased or remained unchanged, in wild type and in the complemented strains.

3-Heterosubstituted Benzofurans from Hydroxyphenyl Propargyl Alcohols via ortho-Quinone Methide through a Metal-/Catalyst-Free Conjugate Addition/Oxy-Cyclization

A facile route to 3-sulfonylated and 3-(1-benzotriazolyl)-benzofurans is achieved from readily available o-hydroxyphenyl propargyl alcohols (o-HPPAs) and bench-top sodium sulfonylates and benzotriazoles with no assistance of any reagent or catalyst. Bifunctional o-quinone methides (o-QMs) were the putative reaction intermediates ensued from dehydration of o-HPPA. Our study revealed that the o-QM was so choosy in selection of the nucleophiles for the key Michael addition reaction.