Tuberculosis

Question: Explaining the function of the target enzyme HSaD within tuberculosis (TB). Answer: Tuberculosis (TB) is a widespread bacterial disease which is caused by different strains of mycobacterium, mainly Mycobacterium tuberculosis. It is highly infectious fatal disease transmitted through various means like air, or when people having active TB infection cough, sneezes. After infecting the body, the bacterium passes through the lymph nodes and blood vessels to all parts of the body but mostly it is found in lungs. Most infections do not show symptoms, known as latent tuberculosis, here they lives in a recessive form in the body. But as the immune system get weaker, TB bacteria become dominant. In their active state they even cause death of tissue to the organs they infect. It causes death if left untreated. As the bacteria that cause tuberculosis are transmitted through air, the disease is contagious. Generally it is evident that it causes to a person who are more exposed to person having TB on a regular basis. TB can infect to any organ of the body, but mostly it occurs in the lung which is known as pulmonary tuberculosis. Extrapulmonary TB occurs outside the lungs, even though extrapulmonary TB may occur simultaneously with pulmonary TB. There are many preliminary systems of TB such as chronic cough with blood-tinged sputum, fever, night sweats, loss of appetite, chills, weight loss and fatigue, nail clubbing etc. Characteristics of the pathogen: Mycobacterium tuberculosis is a small aerobic, non-motile bacillus. This pathogen has various special characteristics for its high lipid content. It divides in extremely slow rate as compared to other bacteria which usually divide in less than an hour, whereas M. tuberculosis usually divides every 16 to 20 hours. Its outer membrane is a lipid bilayer. When a Gram stain test is performed on this pathogen, it either stains Gram positive very weakly or does not retain stain because of its high lipid and mycolic acid content of its cell wall. MTB can survive in dry conditions and withstand weak disinfectants. It can develop naturally only within the host organism but can also be artificially cultured in laboratory. This complex pathogen includes other different TB causing mycobacteria: M. bovis, M. africanum, M. canetti, and M. microti. Among these types M. africanum is not widespread, but it is found in some parts of Africa. The bacterium of tuberculosis affects our body specifically when immune system gets weaker for some reasons or our body is previously overwhelmed by other infections, it is when that the disease occurs. It mostly affects the individuals with weak immune system such as infants, old people, pregnant women, HIV positive people, people living in unsanitary conditions, cancer patients and uncontrolled diabetes patients. When living in close contact with the person already suffering from TB. People consuming excessive alcohols, drug addicted people and individuals who weigh 10% less than recommended body weight. The treatment of TB is a long process and involves strict following doctors instruction. Even if the patients feel better the full course of medicine should be completed. The WHO had given various ways to control TB that is DOTS Directly Observed Treatment, Short Course. Some newer drugs like Bedaquiline, Delaminid and PA-824 are being treated in various clinics all over India. Prevention All of us are exposed to the pathogen of TB but only individuals with less immunity in the body seem to be affected by the disease. Therefore, keeping a healthy body is the primary way to avoid it. Some of the preventions are below: All new born infant should be given the Bacillus Calmette-Guerin (BCG) vaccine to protect against TB. Keep immunity high Maintain good hygiene Early diagnosis is the preliminary way to lessen the number of deaths due to TB. Function Of Target Enzyme HSAD The main cause of death through this disease is the pathogen Mycobacterium tuberculosis which is spread all over the world. It was virtually vanished with the help of antibiotics developed in 1950s, but the disease has reappeared eventually with new forms. Increasing prevalence of multidrug resistant organisms means prioritizing identification of targets for antituberculars. For survival of the microphage 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate hydrolase (HsaD), part of the cholesterol metabolism operon, is essential. The C-C bond hydrolase, HsaD, has a serine protease-like catalytic triad. The role of cholesterol is important in the infection of M.tuberculosis which is becoming increasingly prominent. Cholesterol is essential for phagocytosis of M.tuberculosis by macrophage (Peyron et al., 2000) and also play a main role as an energy source for the bacterial survival in the macrophage (Van der Geize et al., 2007). Gene deletion mutants of HsaC and HsaD show that for the survival of the macrophage these enzymes are necessary (Rangarajan et al., 2005). A subfamily of / hydrolases HsaD is part of the meta-clevage product (MCP) hydrolase class of enzymes (Lack et al., 2008). HsaD catalyses the cleavage of 4,9-DHSA within the cholesterol metabolism reaction (Van der Geize et al., 2007). There are three types of inhibitors verified for activity against HsaD. The largest group is the serine protease inhibitors. Many covalent inhibitors, for e.g., phenylmethylsulphonyl fluoride (PMSF), were tested alongwith non-covalent inhibitors, e.g., benzamidine. Acetylcholinesterases are members of the / hydrolase family and catalyse its reactions via a serine protease-like catalytic triad (Shafferman et al., 1992). A range of acetylcholinesterase-specific inhibitors were also verified, e.g., neostigmine. Humans having a structural homologue of HsaD called monoglyceride lipase (MGL). It shares the whole fold as HsaD and also acts via a serine protease-like catalytic triad, like acetylcholinesterases. A number of MGL-specific inhibitors were verified, e.g., cholesterol-like pristimerin (King et al., 2009). It is said that similar inhibitors were favoured by both of the enzymes because of the hydrophobic nature of the physiological substrates of MGL and HsaD. Spectroscopic Information From (IR, H-NMR And C-NMR) Nuclear magnetic resonance (NMR) spectroscopy is the most preferred way for the metabolic analysis of bio-fluids due to its higher reproducibility, non-destructiveness, non-selectivity in metabolite detection, and the capability to directly quantify multiple classes of metabolites. Tuberculosis (TB) which is a chronic inflammatory disease followed by multisystem involvement, causes metabolic derangements in affected patients. To explore the metabolic profile of sera from TB patients a combined multivariate pattern recognition (PR) analytical techniques with 1H NMR spectroscopy was done. A total of 77 serum samples was collected from patients with TB (n=38) and healthy controls (n=39) were examined. TB patients were distinguished from controls and creating a TB-specific metabolite profile by Orthogonal partial least-squares discriminant analysis (OPLS-DA). In concentration between the two groups a total of 17 metabolites were different specifically. Serum samples of TB patients were characterized by high concentrations of 1- methyl histidine, acetoacetate, acetone, glutamate, glutamine, isoleucine, actate, lysine, nicotinate, phenylalanine, pyruvate, and tyrosine, along with low concentrations of alanine, formate, glysine, glycerolphosphocholine and low density lipoprotein relative to control subjects. This study shows that metabolic profile of sera of TB patients and shows that NMR-based methods can be separated from TB patients from healthy controls. NMR-based metabolomics has the ability to provide the best device of TB diagnosis or with therapeutic monitoring and could add the disease understanding mechanisms better. Rationale Behind Spectroscopic Assignments With 2d NMR The entire structure of triglycosyl diacyl phenol phthiocerol of the TB bacterium was clear using the 2D -IH-NMR spectroscopy, together wih its configuration of sugar residues, composition, arrangements and linkage sites of the trisaccharide and appearance of variants in the lipid moiety. Through analysis of anomeric proton resonances IH-NMR spectroscopy has been widely used as rapid, sensitive, quantitative and non-destructive to determine the sugar composition of mycobacterial mycosides. To deciphered and provide primary and secondary structural data by scalar-correlated and dipolar-correlated spectra overlapping envelopes of resonances of an oligosaccharide is allowed by 2D-NMR.