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...
Antibiotic resistance is now a major threat to human health, and one approach to combating this threat is to develop resistance-resistant antibiotics. Synthetic antimicrobial polymers are generally resistance resistant, having good activity with low resistance rates but usually with low therapeutic indices. Here, we report our solution to this problem by introducing dual-selective mechanisms of action to a short amidine-rich polymer, which can simultaneously disrupt bacterial membranes and bind to bacterial DNA. The oligoamidine shows unobservable resistance generation but high therapeutic indices against many bacterial types, such as ESKAPE strains and clinical isolates resistant to multiple drugs, including colistin. The oligomer exhibited excellent effectiveness in various model systems, killing extracellular or intracellular bacteria in the presence of mammalian cells, removing all bacteria from Caenorhabditis elegans, and rescuing mice with severe infections. This “dual mechanisms of action” approach may be a general strategy for future development of antimicrobial polymers.
In this paper, a new integrable two-component system, m t = [m(u x v x − uv + uv x − u x v)] x , n t = [n(u x v x − uv + uv x − u x v)] x , where m = u − u xx and n = v − v xx , is proposed. Our system is a generalized version of the integrable system m t = [m(u 2 x − u 2)] x , which was shown having cusped solution (cuspon) and W/M-shape soliton solutions by Qiao [J. Math. Phys. 47, 112701 (2006). The new system is proven integrable not only in the sense of Lax-pair but also in the sense of geometry, namely, it describes pseudospherical surfaces. Accordingly, infinitely many conservation laws are derived through recursion relations. Furthermore, exact solutions such as cuspons and W/M-shape solitons are also obtained.
Controlled proteolytic activation of membrane-anchored transcription factors provides an adaptation strategy that guarantees rapid transcriptional responses to abrupt environmental stresses in both animals and plants. NTL6 is a plant-specific NAC [NAM/ATAF1/2/CUC2] transcription factor that is expressed as a dormant plasma membrane-associated form in Arabidopsis. Proteolytic processing of NTL6 is triggered by abiotic stresses and ABA (abscisic acid). In the present study, we show that NTL6 is linked directly with SnRK (Snf1-related protein kinase) 2.8-mediated signalling in inducing a drought-resistance response. SnRK2.8 phosphorylates NTL6 primarily at Thr142. NTL6 phosphorylation by SnRK2.8 is required for its nuclear import. Accordingly, a mutant NTL6 protein, in which Thr142 was mutated to an alanine, was poorly phosphorylated and failed to enter the nucleus. In accordance with the role of SnRK2.8 in drought-stress signalling, transgenic plants overproducing either NTL6 or its active form 6ΔC (35S:NTL6 and 35S:6ΔC) exhibited enhanced resistance to water-deficit conditions such as those overproducing SnRK2.8 (35S:SnRK2.8). In contrast, NTL6 RNAi (RNA interference) plants were susceptible to dehydration as observed in the SnRK2.8-deficient snrk2.8-1 mutant. Furthermore, the dehydration-resistant phenotype of 35S:NTL6 transgenic plants was compromised in 35S:NTL6 X snrk2.8-1 plants. These observations indicate that SnRK2.8-mediated protein phosphorylation, in addition to a proteolytic processing event, is important for NTL6 function in inducing a drought-resistance response.
Proteome analysis by 2-DE and PMF by MALDI-TOF MS was performed on human amnion and amniotic fluid at term. Ninety-two soluble and nineteen membrane proteins were identified from amnion. Thirty-five proteins were identified from amniotic fluid. Calgranulin A and B were found in all patients infected with Ureaplasma urealyticum, but not in any of the patients without infection, indicating that they are potential markers of intrauterine infection. Identity of calgranulin A and B was confirmed by MALDI-TOF/TOF MS. This study represents the first extensive analysis of the human amnion and amniotic fluid proteome at term and demonstrates that 2-DE and MALDI-TOF MS is a useful tool for identifying clinically significant biomarkers of problematic pregnancies.
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