Lipid and protein membrane components associated with cholesterol uptake by mycoplasmas

Efrati, Hava; Rottem, Shlomo; Razin, Shmuel

doi:10.1016/0005-2736(81)90494-6

Cited by 17 publications

(8 citation statements)

References 24 publications

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“…Like other mycoplasmas, M. pulmonis lacks several biosynthetic pathways and is dependent on the host cell for supplying many macromolecular components, including lipids and cholesterol (16). The mechanism by which mycoplasmas obtain these host membrane components is not understood, but previous studies have suggested that there is a directional flow of host membrane proteins (21,22) and lipids (7) to the mycoplasma during membrane-membrane interactions. Some investigators have suggested that membrane fusion occurs at the interface between the mycoplasma and the host cell (3,5).…”

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confidence: 99%

Trypsin-sensitive, bovine serum albumin-dependent hemolysis activity in Mycoplasma pulmonis

Minion¹,

Goguen²

1985

Infect Immun

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Although Mycoplasma pulmonis did not lyse normal erythrocytes, it rapidly lysed erythrocytes that had cytoskeletal deficiencies which allow increased diffusion of membrane glycophorin or that had been treated with trypsin to remove surface proteins. This hemolysis occurred only in the presence of bovine serum albumin and was eliminated by trypsin treatment of the mycoplasma. Hemolytic activity was restored after such trypsin treatment when mycoplasma protein synthesis was allowed. M. pulmonis hemolytic activity was not diffusible and thus differed from the activities reported for other mycoplasmas, which involve small diffusible intermediates such as hydrogen peroxide. With the exception of the requirement for bovine serum albumin, the factors which affected hemolysis were similar to those which we have previously reported to affect M. pulmonis hemagglutination, suggesting that these two activities are functionally related.on July 15, 2020 by guest http://iai.asm.org/ Downloaded from

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confidence: 99%

Trypsin-sensitive, bovine serum albumin-dependent hemolysis activity in Mycoplasma pulmonis

Minion¹,

Goguen²

1985

Infect Immun

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“…Previous studies support the hypothesis that milL may be involved in the acquisition of membrane precursors. Phospholipid and cholesterol were taken up simultaneously in M. gallisepticum by a BSA-enhanced [16], trypsin-sensitive mechanism [15] implying that a protein receptor or activity was involved. Similarly, mycoplasmal milL activity was trypsin-sensitive and required BSA [3].…”

Section: Phospholipase C Activitymentioning

confidence: 99%

“…Outside the Mollicutes, Serpulina hyodysenteriae is the only eubacteria identified as having a growth requirement for cholesterol [13]. Cholesterol has been shown to readily exchange between phospholipid bilayers through a mechanism involving intermittent contact or a soluble intermediate carrier [14], but in mycoplasmas uptake of cholesterol is protein-dependent [15]. Also, the need for phospholipids as an absolute growth requirement is unusual in the prokaryotes.…”

Section: Phospholipase C Activitymentioning

confidence: 99%

Membrane-associated hemolysin activities in mycoplasmas

Minion

Jarvill-Taylor

1994

FEMS Microbiology Letters

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Mycoplasmas are cell wall-less organisms that require membrane precursors for growth. Activities involved in the acquisition of these materials have been hypothesized as mycoplasmal virulence factors because of the effects these activities might have on host cells. Twenty-nine species or strains of mycoplasmas were examined for membrane-associated hemolysis activity similar to that previously identified in Mycoplasma pulmonis. Membrane-associated hemolytic activity was found in most mycoplasma species, but the amount of activity varied between and within the species. All of the arginine-utilizing mycoplasmal species, one M. pulmonis strain, one Acholeplasma species, and the intracellular human pathogens M. penetrans and M. fermentans ssp. incognitus were devoid of activity. The wide distribution of the membrane-associated hemolysis activity suggests that it may be important to the survival of the organism.

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“…The incorporated lipids are intercalated into the bulk lipid bilayer (27). In M. capricolum the incorporation of exogenous PC was found to alter the de novosynthesized phospholipids as well as the physical properties of the membrane (11), and more recently, the ability of mycoplasmas to incorporate exogenous phospholipids was correlated with their ability to take up cholesterol (8). In M. gallisepticum, cell growth was found to be greatly stimulated by the incorporation of exogenous SPM (22).…”

mentioning

confidence: 98%

Incorporation and modification of exogenous phosphatidylcholines by mycoplasmas

Rottem¹,

Adar²,

Gross³

et al. 1986

J Bacteriol

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The uptake and modification of exogenous phosphatidylcholine (PC) by several Mycoplasma and Spiroplasma species was investigated. While in most Mycoplasma species and in all Spiroplasma species tested the PC appears to be incorporated unchanged from the growth medium, the PC of M. gallisepticum, M. pulmonis, and M. pneumoniae was disaturated PC, apparently formed by modification of l-saturated-2-unsaturated PC from the growth medium. The modification of the exogenous PC by M. gallisepticum was inhibited by chloramphenicol under conditions that did not affect de novo synthesis of phosphatidylglycerol. A low activity of an endogenous phospholipase A was detected in native M. gallisepticum membranes. The activity was markedly stimulated by treating the membranes with low concentrations of the nonionic detergents. The PC modification was affected by the fatty acid composition of the exogenous PC species. Diunsaturated, l-saturated-2-unsaturated, and l-unsaturated-2-saturated PCs were modified to various extents, whereas the disaturated dipalmitoyl PC (DPPC) was not. Both modified and unmodified PCs were incorporated by the cells, but the unmodified DPPC was incorporated at a lower rate and to a lesser extent. The possibility that the incorporation of DPPC into M. gallisepticum cells is associated with the formation of intracytoplasmic membranes is discussed.In the absence of a rigid cell wall (19), the cell membrane of mycoplasmas interacts directly with components of the growth medium. Most mycoplasmas are fastidious organisms requiring serum for growth (19,30). Direct interaction of Mycoplasma or Spiroplasma species with the serum lipoprotein particles or other exogenous lipid donors results in the incorporation of exogenous lipid from the growth medium (6,18,20,25). Since the major phospholipids in serum-containing growth medium are phosphatidylcholine (PC) and sphingomyelin (SPM), these phospholipids are the major phospholipids incorporated (20). Some Mycoplasma species incorporate more PC than SPM (20), whereas others, as well as all the Spiroplasma species tested, incorporate more SPM (6,20). The incorporated lipids are intercalated into the bulk lipid bilayer (27). In M. capricolum the incorporation of exogenous PC was found to alter the de novosynthesized phospholipids as well as the physical properties of the membrane (11), and more recently, the ability of mycoplasmas to incorporate exogenous phospholipids was correlated with their ability to take up cholesterol (8). In M. gallisepticum, cell growth was found to be greatly stimulated by the incorporation of exogenous SPM (22). The incorporation of exogenous phospholipids was first investigated by us in M. gallisepticum (25) in which it was found that the SPM was incorporated unchanged whereas the PC was modified by the cells. The modification involves the replacement of the unsaturated fatty acid that occupies position 2 of the serum PC with a saturated fatty acid giving rise to a disaturated PC.In this report we show that the modification of exogenous PC ...

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Lipid and protein membrane components associated with cholesterol uptake by mycoplasmas

Cited by 17 publications

References 24 publications

Trypsin-sensitive, bovine serum albumin-dependent hemolysis activity in Mycoplasma pulmonis

Trypsin-sensitive, bovine serum albumin-dependent hemolysis activity in Mycoplasma pulmonis

Membrane-associated hemolysin activities in mycoplasmas

Incorporation and modification of exogenous phosphatidylcholines by mycoplasmas

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