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Catalase is a common enzyme found in nearly all living organisms exposed to oxygen which catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting the cell from oxidative damage by reactive oxygen species (ROS). Likewise, catalase has one of the highest turnover numbers of all enzymes; one catalase molecule can convert millions of hydrogen peroxide molecules to water and oxygen each second.
Glutathione peroxidase (GPx) is the general name of an enzyme family with peroxidase activity whose main biological role is to protect the organism from oxidative damage. The biochemical function of glutathione peroxidase is to reduce lipid hydroperoxides to their corresponding alcohols and to reduce free hydrogen peroxide to water.
Mycobacterium tuberculosis is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, M. tuberculosis has an unusual, waxy coating on its cell surface primarily due to the presence of mycolic acid. This coating makes the cells impervious to Gram staining, and as a result, M. tuberculosis can appear either Gram-negative or Gram-positive. Acid-fast stains such as Ziehl–Neelsen, or fluorescent stains such as auramine are used instead to identify M. tuberculosis with a microscope. The physiology of M. tuberculosis is highly aerobic and requires high levels of oxygen. Primarily a pathogen of the mammalian respiratory system, it infects the lungs. The most frequently used diagnostic methods for tuberculosis are the tuberculin skin test, acid-fast stain, culture, and polymerase chain reaction.
Isoniazid, also known as isonicotinic acid hydrazide (INH), is an antibiotic used for the treatment of tuberculosis. For active tuberculosis it is often used together with rifampicin, pyrazinamide, and either streptomycin or ethambutol. For latent tuberculosis it is often used by itself. It may also be used for atypical types of mycobacteria, such as M. avium, M. kansasii, and M. xenopi. It is usually taken by mouth but may be used by injection into muscle.
Rifampicin, also known as rifampin, is an antibiotic used to treat several types of bacterial infections, including tuberculosis (TB), Mycobacterium avium complex, leprosy, and Legionnaires’ disease. It is almost always used together with other antibiotics with two notable exceptions: when given as a "preferred treatment that is strongly recommended" for latent TB infection; and when used as post-exposure prophylaxis to prevent Haemophilus influenzae type b and meningococcal disease in people who have been exposed to those bacteria. Before treating a person for a long period of time, measurements of liver enzymes and blood counts are recommended. Rifampicin may be given either by mouth or intravenously.
Pyrazinamide is a medication used to treat tuberculosis. For active tuberculosis, it is often used with rifampicin, isoniazid, and either streptomycin or ethambutol. It is not generally recommended for the treatment of latent tuberculosis. It is taken by mouth.
The rpoB gene encodes the β subunit of bacterial RNA polymerase. rpoB is also found in plant chloroplasts where it forms the beta subunit of the plastid-encoded RNA polymerase (PEP). An inhibitor of transcription in bacteria, tagetitoxin, also inhibits PEP, showing that the complex found in plants is very similar to the homologous enzyme in bacteria. It codes for 1342 amino acids, making it the second-largest polypeptide in the bacterial cell. It is the site of mutations that confer resistance to the rifamycin antibacterial agents, such as rifampin. Mutations in rpoB that confer resistance to rifamycins do so by altering residues of the rifamycin binding site on RNA polymerase, thereby reducing rifamycin binding affinity for rifamycins
Ethionamide is an antibiotic used to treat tuberculosis. Specifically it is used, along with other antituberculosis medications, to treat active multidrug-resistant tuberculosis. It is no longer recommended for leprosy. It is taken by mouth.
Acyl-CoA dehydrogenases (ACADs) are a class of enzymes that function to catalyze the initial step in each cycle of fatty acid β-oxidation in the mitochondria of cells. Their action results in the introduction of a trans double-bond between C2 (α) and C3 (β) of the acyl-CoA thioester substrate. Flavin adenine dinucleotide (FAD) is a required co-factor in addition to the presence of an active site glutamate in order for the enzyme to function.
Lipoarabinomannan, also called LAM, is a glycolipid, and a virulence factor associated with Mycobacterium tuberculosis, the bacteria responsible for tuberculosis. Its primary function is to inactivate macrophages and scavenge oxidative radicals.
Multidrug-resistant tuberculosis (MDR-TB) is a form of tuberculosis (TB) infection caused by bacteria that are resistant to treatment with at least two of the most powerful first-line anti-TB medications (drugs), isoniazid and rifampin. Some forms of TB are also resistant to second-line medications, and are called extensively drug-resistant TB (XDR-TB).
Isocitrate lyase, or ICL, is an enzyme in the glyoxylate cycle that catalyzes the cleavage of isocitrate to succinate and glyoxylate. Together with malate synthase, it bypasses the two decarboxylation steps of the tricarboxylic acid cycle and is used by bacteria, fungi, and plants.
In enzymology, a glycerol-1-phosphatase (EC 3.1.3.21) is an enzyme that catalyzes the chemical reaction
In enzymology, a malate synthase (EC 2.3.3.9) is an enzyme that catalyzes the chemical reaction
PncA is a gene encoding pyrazinamidase in Mycobacterium species. Pyrazinamidase converts the drug pyrazinamide to the active form pyrazinoic acid. There is a strong correlation between mutations in pncA and resistance of M. tuberculosis to pyrazinamide.
The Mycobacterium tuberculosis complex is a genetically related group of Mycobacterium species that can cause tuberculosis in humans or other animals.
Catalase-peroxidase (EC 1.11.1.21, katG (gene)) is an enzyme with systematic name donor:hydrogen-peroxide oxidoreductase. This enzyme catalyses the following chemical reaction
- donor + H2O2 ⇌ oxidized donor + 2 H2O
- 2 H2O2 ⇌ O2 + 2 H2O
Oxidation response is stimulated by a disturbance in the balance between the production of reactive oxygen species and antioxidant responses, known as oxidative stress. Active species of oxygen naturally occur in aerobic cells and have both intracellular and extracellular sources. These species, if not controlled, damage all components of the cell, including proteins, lipids and DNA. Hence cells need to maintain a strong defense against the damage. The following table gives an idea of the antioxidant defense system in bacterial system.
Eosinophil peroxidase is an enzyme found within the eosinophil granulocytes, innate immune cells of humans and mammals. This oxidoreductase protein is encoded by the gene EPX, expressed within these myeloid cells. EPO shares many similarities with its orthologous peroxidases, myeloperoxidase (MPO), lactoperoxidase (LPO), and thyroid peroxidase (TPO). The protein is concentrated in secretory granules within eosinophils. Eosinophil peroxidase is a heme peroxidase, its activities including the oxidation of halide ions to bacteriocidal reactive oxygen species, the cationic disruption of bacterial cell walls, and the post-translational modification of protein amino acid residues.
MUBII-TB-DB is a database that focuses on tuberculosis antibiotic resistance genes. It is a highly structured, text-based database focusing on Mycobacterium tuberculosis at seven different mutation loci: rpoB, pncA, katG; mabA(fabG1)-inhA, gyrA, gyrB, and rrs. MUBII analyzes the query using two parallel strategies: 1). A BLAST search against previously mutated sequences. 2). Alignment of query sequences with wild-type sequences. MUBII outputs graphs of alignments and description of the mutation and therapeutic significance. Therapeutically relevant mutations are tagged as "High-Confident" based on the criteria set by Sandgren et al. MUBII-TB-DB provides a platform that is easy to use for even users that are not trained in bioinformatics.
References
- ↑ Johnsson, Kai (1997). "Overexpression, Purification, and Characterization of the Catalase-peroxidase KatG from Mycobacterium tuberculosis". Journal of Biological Chemistry. 272 (5): 2834–2840. doi: 10.1074/jbc.272.5.2834 . PMID 9006925. S2CID 23882303 – via Elsevier.
- ↑ Heym, B (July 1993). "Characterization of the katG gene encoding a catalase-peroxidase required for the isoniazid susceptibility of Mycobacterium tuberculosis". Journal of Bacteriology. 175 (13): 4255–4259. doi:10.1128/jb.175.13.4255-4259.1993. PMC 204858 . PMID 8320241.
- ↑ Cockerill, FR (1995). "Rapid identification of a point mutation of the Mycobacterium tuberculosis catalase-peroxidase (katG) gene associated with isoniazid resistance". The Journal of Infectious Diseases. 171 (1): 240–245. doi:10.1093/infdis/171.1.240. PMID 7798673 – via Pubmed.
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