Mycobacterium tuberculosis Eis protein initiates suppression of host immune responses by acetylation of DUSP16/MKP-7

Abstract

The intracellular pathogen Mycobacterium tuberculosis (Mtb) causes tuberculosis. Enhanced intracellular survival (Eis) protein, secreted by Mtb, enhances survival of Mycobacterium smegmatis (Msm) in macrophages. Mtb Eis was shown to suppress host immune defenses by negatively modulating autophagy, inflammation, and cell death through JNK-dependent inhibition of reactive oxygen species (ROS) generation. Mtb Eis was recently demonstrated to contribute to drug resistance by acetylating multiple amines of aminoglycosides. However, the mechanism of enhanced intracellular survival by Mtb Eis remains unanswered. Therefore, we have characterized both Mtb and Msm Eis proteins biochemically and structurally. We have discovered that Mtb Eis is an efficient N ɛ -acetyltransferase, rapidly acetylating Lys55 of dualspecificity protein phosphatase 16 (DUSP16)/mitogen-activated protein kinase phosphatase-7 (MKP-7), a JNK-specific phosphatase. In contrast, Msm Eis is more efficient as an N α -acetyltransferase. We also show that Msm Eis acetylates aminoglycosides as readily as Mtb Eis. Furthermore, Mtb Eis, but not Msm Eis, inhibits LPSinduced JNK phosphorylation. This functional difference against DUSP16/MKP-7 can be understood by comparing the structures of two Eis proteins. The active site of Mtb Eis with a narrow channel seems more suitable for sequence-specific recognition of the protein substrate than the pocket-shaped active site of Msm Eis. We propose that Mtb Eis initiates the inhibition of JNK-dependent autophagy, phagosome maturation, and ROS generation by acetylating DUSP16/MKP-7. Our work thus provides insight into the mechanism of suppressing host immune responses and enhancing mycobacterial survival within macrophages by Mtb Eis.Rv2416c | lysine acetylation | antituberculosis drug N early one-third of the world's population is infected with Mycobacterium tuberculosis (Mtb). This pathogenic bacterium causes tuberculosis, which claims the lives of millions of people every year (1). Tuberculosis has also become a global health issue owing to the increased incidences of multidrug-resistant and extensively drug-resistant strains of Mtb (2). This makes a search for targets of new antituberculosis drugs urgent. Mtb is a highly successful human pathogen, surviving and multiplying within the human macrophage cells of the infected people (3). Therefore, treatment of tuberculosis is difficult, requiring many months of taking a combination of antibiotics. Mtb has the ability to persist in the form of a long-term asymptomatic infection, referred to as latent tuberculosis (4). Latent tuberculosis becomes activated when the body's immune system is weakened. As a result, tuberculosis is the major cause of death among immuno-compromised AIDS patients (5).In mycobacterial infection, host innate immune responses may play a crucial role in early protection against Mtb infection, leading to establishment of effective adaptive immunity to tuberculosis (6). Additionally, MAPK pathways are activated by Mtb or its components and play an e...

A Combined “Omics” Approach Identifies N-Myc Interactor as a Novel Cytokine-induced Regulator of IRE1α Protein and c-Jun N-terminal Kinase in Pancreatic Beta Cells

“…This maybe due to the cytokine-dependent induction, in parallel with NMI, of other JNK regulators. Our RNA sequencing data of cytokine-treated human islet cells (30) support this hypothesis, showing a significant up-regulation of several phosphatases such DUSP1 (65) and DUSP16 (66,67) in IL-1␤ ϩ IFN-␥-treated islets.…”

Autophagy in the Fight Against Tuberculosis

“…While M. tuberculosis-Eis significantly downregulates lipopolysaccharideinduced JNK phosphorylation, M. smegmatis-Eis does not reveal this function. Therefore, acetylation of DUSP16 by M. tuberculosis-Eis seems to be the key initial event in the JNK-dependent inhibition of autophagy, phagosome maturation, and ROS generation, which ultimately contribute to enhanced survival of M. tuberculosis within the macrophage cells (Kim et al, 2012b). This also suggests that M. tuberculosis developed adaptive evolutionary strategies to potentiate the suppression of the host innate immune system.…”

“…Interestingly, the Eis protein secreted by M. tuberculosis appears to enhance survival of other mycobacteria, namely Mycobacterium smegmatis, in macrophages. M. tuberculosis-Eis is an efficient N e -acetyltransferase rapidly acetylating Lys55 of the dual-specificity protein phosphatase 16 (DUSP16; also known as MKP-7), a JNK-specific phosphatase, whereas M. smegmatis-Eis is more efficient as an N a -acetyltransferase and preferentially acetylates the terminal amino group of peptides (Kim et al, 2012b). This difference between both proteins is likely to be explained by a structural dissimilarity in the peptide recognition pocket of the enzymes; M. tuberculosis-Eis is characterized by the presence of a narrow channel, while M. smegmatis-Eis has a deep, roundshaped substrate-binding pocket, which seems more suitable for accommodating the terminal amino group of peptides than specific sequences within proteins (Kim et al, 2012b).…”

Interaction of Mycobacterium tuberculosis with Host Cell Death Pathways

“…Another Mtb protein that targets host cell ROS is the enhanced intracellular survival (eis) protein. Nevertheless, it can inhibit not only NOX2-generated phagosomal ROS but also mitochondrial ROS via inhibition of the intracellular kinase JNK (Kim et al 2012). eis is a secreted protein that reaches the host cell cytosol and, via its acetyltransferase activity, acetylates the phosphatase DUSP16/MKP-7 that increases its activity to dephosphorylate and hence inactivate JNK (Kim et al 2012).…”

“…Nevertheless, it can inhibit not only NOX2-generated phagosomal ROS but also mitochondrial ROS via inhibition of the intracellular kinase JNK (Kim et al 2012). eis is a secreted protein that reaches the host cell cytosol and, via its acetyltransferase activity, acetylates the phosphatase DUSP16/MKP-7 that increases its activity to dephosphorylate and hence inactivate JNK (Kim et al 2012). The eis Mtb mutant induces caspase-independent apoptosis and autophagy that is different from the nuoG mutant that induces caspase-dependent apoptosis and no autophagy (Miller et al 2010;L Srinivasan, unpubl.).…”