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Category: Fungi and Fungal Pathogenesis; Clinical Microbiology
Metabolism of Mycobacterium tuberculosis, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555818357/9781555819101_Chap23-1.gif /docserver/preview/fulltext/10.1128/9781555818357/9781555819101_Chap23-2.gifAbstract:
Researchers in mycobacterial biochemistry have almost exclusively concentrated their efforts on those aspects of metabolism that appear to be unique to members of the genus Mycobacterium and have, in the absence of information to the contrary, assumed that other aspects of metabolism will be more or less the same as those of other, more amenable bacteria. In this chapter, the authors have chosen to follow the same elective pathway, concentrating on those aspects of metabolism that appear to be at least in some way unique to the mycobacteria and are, moreover, of relevance to the growth of Mycobacterium tuberculosis as a pathogen within the tissues and fluids of its host. The peptidoglycan in mycobacteria is of a type common in many bacteria but with two slight differences. First, there are interpeptide linkages between two diaminopimelate residues as well as the usual D-alanyl-diaminopimelate linkages. Second, the usual N-acetylmuramic acid is replaced with N-glycolyl-muramic acid in M. bovis and in other mycobacteria. An approach that might be appropriate would be to make probes for M. tuberculosis DNA based on appropriate genes identified in muramic acid metabolism from other microbes, as these genes would be expected to have some sequence similarity in all bacteria. There are many interesting and important implications for the new field of mycobacterial genetics: the complex organization of these microbes demands multiple genes for fatty acid biosynthesis and seemingly innumerable glycosyltransferase genes.
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Metabolism of host carbon sources by intracellular mycobacteria (adapted from Barclay and Wheeler [1989] ). In addition, mycobacteria may also assimilate purines and pyrimidines and use these for nucleic acid biosynthesis. TCA, tricarboxylic acid.
Metabolism of host carbon sources by intracellular mycobacteria (adapted from Barclay and Wheeler [1989] ). In addition, mycobacteria may also assimilate purines and pyrimidines and use these for nucleic acid biosynthesis. TCA, tricarboxylic acid.
Iron assimilation in microorganisms.
Iron assimilation in microorganisms.
Structure of mycobactin, the intracellular siderophore of mycobacteria. For structures of other mycobactins, see Snow (1970) and Barclay et al. (1985) . Substituents: R1, alkyl chain up to C19, often with double bond at cis Δ2 position, though occasionally, as with M. marinum, this can be CH3; R2, —H or —CH3; R3 —H or —CH3; R4, usually —CH3 or —C2H5, though occasionally, as with M. marinum, a long alkyl chain up to C17; R5, —H or —CH3. For M. tuberculosis, R1 is—C19H37, R2 = R3 = R5 = —H, and R4 is —CH3.
Structure of mycobactin, the intracellular siderophore of mycobacteria. For structures of other mycobactins, see Snow (1970) and Barclay et al. (1985) . Substituents: R1, alkyl chain up to C19, often with double bond at cis Δ2 position, though occasionally, as with M. marinum, this can be CH3; R2, —H or —CH3; R3 —H or —CH3; R4, usually —CH3 or —C2H5, though occasionally, as with M. marinum, a long alkyl chain up to C17; R5, —H or —CH3. For M. tuberculosis, R1 is—C19H37, R2 = R3 = R5 = —H, and R4 is —CH3.
Mechanism of iron uptake in mycobacteria as mediated by the exochelins and mycobactins.
Mechanism of iron uptake in mycobacteria as mediated by the exochelins and mycobactins.
Possible biosynthetic pathways for phosphatidylinositolmannosides (PIMX). PIM1 is strictly an intermediate and does not accumulate.
Possible biosynthetic pathways for phosphatidylinositolmannosides (PIMX). PIM1 is strictly an intermediate and does not accumulate.
Early dedicated stages of mycolate biosynthesis. a, Speculated—reaction sought but not shown; b, see Wheeler et al., 1993b; c, methylation reaction shown but not for 24:1 cis-5.
Early dedicated stages of mycolate biosynthesis. a, Speculated—reaction sought but not shown; b, see Wheeler et al., 1993b; c, methylation reaction shown but not for 24:1 cis-5.
Biosynthesis of methylmannose polysaccharide, x = 3 to 12.
Biosynthesis of methylmannose polysaccharide, x = 3 to 12.
Substrates that may be available to mycobacteria growing in the host a
Substrates that may be available to mycobacteria growing in the host a
Growth and rates of synthesis of nucleic acids
Growth and rates of synthesis of nucleic acids
Heat shock proteins in M. tuberculosis and M. bovis
Heat shock proteins in M. tuberculosis and M. bovis
Occurrence of IREPs and HIPs as analyzed by SDS-PAGE in mycobacteria grown in vitro and in vivo a
Occurrence of IREPs and HIPs as analyzed by SDS-PAGE in mycobacteria grown in vitro and in vivo a
Mannosyltransferases detected in mycobacteria
Mannosyltransferases detected in mycobacteria