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

<jats:p> The intracellular pathogen <jats:italic>Mycobacterium tuberculosis</jats:italic> ( <jats:italic>Mtb</jats:italic> ) causes tuberculosis. Enhanced intracellular survival (Eis) protein, secreted by <jats:italic>Mtb</jats:italic> , enhances survival of <jats:italic>Mycobacterium smegmatis</jats:italic> ( <jats:italic>Msm</jats:italic> ) in macrophages. <jats:italic>Mtb</jats:italic> 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. <jats:italic>Mtb</jats:italic> Eis was recently demonstrated to contribute to drug resistance by acetylating multiple amines of aminoglycosides. However, the mechanism of enhanced intracellular survival by <jats:italic>Mtb</jats:italic> Eis remains unanswered. Therefore, we have characterized both <jats:italic>Mtb</jats:italic> and <jats:italic>Msm</jats:italic> Eis proteins biochemically and structurally. We have discovered that <jats:italic>Mtb</jats:italic> Eis is an efficient <jats:italic>N</jats:italic> <jats:sup>ɛ</jats:sup> -acetyltransferase, rapidly acetylating Lys55 of dual-specificity protein phosphatase 16 (DUSP16)/mitogen-activated protein kinase phosphatase-7 (MKP-7), a JNK-specific phosphatase. In contrast, <jats:italic>Msm</jats:italic> Eis is more efficient as an <jats:italic>N</jats:italic> <jats:sup>α</jats:sup> -acetyltransferase. We also show that <jats:italic>Msm</jats:italic> Eis acetylates aminoglycosides as readily as <jats:italic>Mtb</jats:italic> Eis. Furthermore, <jats:italic>Mtb</jats:italic> Eis, but not <jats:italic>Msm</jats:italic> Eis, inhibits LPS-induced JNK phosphorylation. This functional difference against DUSP16/MKP-7 can be understood by comparing the structures of two Eis proteins. The active site of <jats:italic>Mtb</jats:italic> Eis with a narrow channel seems more suitable for sequence-specific recognition of the protein substrate than the pocket-shaped active site of <jats:italic>Msm</jats:italic> Eis. We propose that <jats:italic>Mtb</jats:italic> 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 <jats:italic>Mtb</jats:italic> Eis. </jats:p>