Transformation of sterols byMycobacterium vaccae: effect of lecithin on the permeability of cell envelopes to sterols

Rumijowska, A.; Lisowska, Katarzyna; Ziótkowski, A.; Sedlaczek, L

doi:10.1007/bf02770813

Cited by 25 publications

(16 citation statements)

References 23 publications

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“…As shown for Mycobacterium vaccae and relative strains, CW permeability for androstane steroids is promoted by vancomycin (Lisowska et al, 1996), glycine (Sedlaczek et al, 1999), lecithin (Rumijowska et al, 1997) and polycations (protamine, polymyxin B nonapeptide and polyethyleneimine) (Korycka-Machala et al, 2001). The inhibition of peptidoglycan synthesis by glycine (15 mg ml…”

Section: Introductionmentioning

confidence: 95%

“…Glycine was shown to alter the ratio of mycolic acids to other lipids. Lecithin influenced the fatty acid profile of the CW, thus resulting in greater 4-androstene-3,17-dione (AD) and 1,4-androstadiene-3,17-dione (ADD) formation from sitosterol (Rumijowska et al, 1997). Protamine altered the content of non-covalently bound lipids in the outer leaflet of the lipid bilayer, shifted the ratio of fatty acids and influenced the integrity and fluidity of the bilayer.…”

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confidence: 99%

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Methyl-β-cyclodextrin alters growth, activity and cell envelope features of sterol-transforming mycobacteria

et al. 2007

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Modified b-cyclodextrins have been shown previously to enhance sterol conversion to 4-androstene-3,17-dione (AD) and 1,4-androstadiene-3,17-dione (ADD) by growing Mycobacterium spp. The enhancement effect was mainly attributed to steroid solubilization by the formation of inclusion complexes with modified cyclodextrins. In this work, the influence of randomly methylated b-cyclodextrin (MCD) on the growth, AD-and ADD-producing activity, cell wall (CW) composition and ultrastructure of sterol-transforming Mycobacterium sp. VKM Ac-1816D was studied. The specific growth rate of the strain on glycerol increased in the presence of MCD (20-100 mM). Washed cells grown in the presence of MCD (20-40 mM) expressed 1.6-fold higher ADD-producing activity than did the cells grown without MCD, and their adhesiveness differed. Electron microscopy showed MCD-mediated CW exfoliation and accumulation of membrane-like structures outside the cells, while preserving cells intact. The analysis of CW composition revealed both a decrease in the proportion of extractable lipids and a considerable shift in fatty acid profile resulting from MCD action. The MCD-mediated enhancement of mycolic and fatty acids content was observed outside the cells. The total secreted protein level rose 2.4-fold, and the extracellular 3-hydroxysteroid oxidase activity 3.2-fold. The composition of the CW polysaccharide was not altered, while the overall proportion of the carbohydrates in the CW of the MCD-exposed mycobacteria increased. The results showed that the multiple mechanisms of MCD-mediated intensification of sterol to AD(D) conversion by mycobacteria include not only solubilization of steroids, but also the increase of CW permeability for both steroids and soluble nutrients, disorganization of the lipid bilayer and the release of steroid-transforming enzymes weakly associated with the CW.

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Section: Introductionmentioning

confidence: 95%

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confidence: 99%

Methyl-β-cyclodextrin alters growth, activity and cell envelope features of sterol-transforming mycobacteria

et al. 2007

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“…To follow the process of cholesterol biotransformation and detect intermediates, 5-ml samples were withdrawn from the culture at 24-h intervals and extracted three times with an equal volume of chloroform. The extracts were dried under a vacuum, the residue was dissolved in 0.5 ml of acetone, and the isolated steroids were analyzed by gas chromatography as previously described (34).…”

Section: Methodsmentioning

confidence: 99%

Mycobacterium tuberculosis Is Able To Accumulate and Utilize Cholesterol

et al. 2009

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It is expected that the obligatory human pathogen Mycobacterium tuberculosis must adapt metabolically to the various nutrients available during its cycle of infection, persistence, and reactivation. Cholesterol, which is an important part of the mammalian cytoplasmic membrane, is a potential energy source. Here, we show that M. tuberculosis grown in medium containing a carbon source other than cholesterol is able to accumulate cholesterol in the free-lipid zone of its cell wall. This cholesterol accumulation decreases the permeability of the cell wall for the primary antituberculosis drug, rifampin, and partially masks the mycobacterial surface antigens. Furthermore, M. tuberculosis was able to grow on mineral medium supplemented with cholesterol as the sole carbon source. Targeted disruption of the Rv3537 (kstD) gene inhibited growth due to inactivation of the cholesterol degradation pathway, as evidenced by accumulation of the intermediate, 9-hydroxy-4-androstene-3,17-dione. Our findings that M. tuberculosis is able to accumulate cholesterol in the presence of alternative nutrients and use it when cholesterol is the sole carbon source in vitro may facilitate future studies into the pathophysiology of this important deadly pathogen.Mycobacterium tuberculosis, the causative agent of tuberculosis, is a very successful pathogen that infects one-third of the human population (21). Only 10% of primary infected individuals develop active disease during their lifetimes. Tubercle bacilli are able to persist in a dormant state, from which they may reactivate and induce the contagious disease state (13). In asymptomatic hosts, M. tuberculosis exists in reservoirs called granulomas, which are cellular aggregates that restrict bacterial spreading (40). Granulomas are organized collections of mature macrophages that exhibit a certain typical morphology and that arise in response to persistent intracellular pathogens (1, 4). Pathogenic mycobacteria can induce the formation of foamy macrophages filled with lipid-containing bodies; these have been postulated to act as a secure, nutrient-rich reservoir for tubercle bacilli (31). Moreover, M. tuberculosis DNA has been detected in fatty tissues surrounding the kidneys, as well as those of the stomach, lymph nodes, heart, and skin. Tubercle bacilli are able to enter adipocytes, where they accumulate within intracytoplasmic lipid inclusions and survive in a nonreplicating state (26). In vivo, it is expected that M. tuberculosis adapts metabolically to nutrient-poor conditions characterized by glucose deficiency and an abundance of fatty acids (25,26). The presence of a complex repertoire of lipid metabolism genes in the genome of M. tuberculosis suggests that lipids, including steroids, are important alternative carbon and energy sources for this pathogen (7).One attractive potential alternative nutrient that is readily available in the mammalian host is cholesterol, a major sterol of the plasma membrane. The presence of cholesterol in lipid rafts is required in order for microorga...

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“…The extracts were dried under vacuum, the residue was dissolved in 0?5 ml acetone and steroids were analysed by chromatography as described previously (Rumijowska et al, 1997).…”

Section: Methodsmentioning

confidence: 99%

Identification and targeted disruption of the gene encoding the main 3-ketosteroid dehydrogenase in Mycobacterium smegmatis

et al. 2005

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The catabolic potential for sterol degradation of fast-growing mycobacteria is well known. However, no genes or enzymes responsible for the steroid degradation process have been identified as yet in these species. One of the key enzymes required for degradation of the steroid ring structure is 3-ketosteroid D 1 -dehydrogenase (KsdD). The recent annotation of the Mycobacterium smegmatis genome (TIGR database) revealed six KsdD homologues. Targeted disruption of the MSMEG5898 (ksdD-1) gene, but not the MSMEG4855 (ksdD-2) gene, resulted in partial inactivation of the cholesterol degradation pathway and accumulation of the intermediate 4-androstene-3,17-dione. This effect was reversible by the introduction of the wild-type ksdD-1 gene into M. smegmatis DksdD-1 or overexpression of ksdD-2. The data indicate that KsdD1 is the main KsdD in M. smegmatis, but that KsdD2 is able to perform the cholesterol degradation process when overproduced.

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Transformation of sterols byMycobacterium vaccae: effect of lecithin on the permeability of cell envelopes to sterols

Cited by 25 publications

References 23 publications

Methyl-β-cyclodextrin alters growth, activity and cell envelope features of sterol-transforming mycobacteria

Methyl-β-cyclodextrin alters growth, activity and cell envelope features of sterol-transforming mycobacteria

Mycobacterium tuberculosis Is Able To Accumulate and Utilize Cholesterol

Identification and targeted disruption of the gene encoding the main 3-ketosteroid dehydrogenase in Mycobacterium smegmatis

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