Cytoplasmic membrane of Rhizobium meliloti bacteroids. I. Alterations in lipid composition, physical properties, and respiratory proteins

1983 ◽  
Vol 61 (12) ◽  
pp. 1334-1340 ◽  
Author(s):  
R. W. Miller ◽  
P. A. Tremblay
Keyword(s):  
Fatty Acid ◽  
Physical Properties ◽  
Lipid Composition ◽  
Cytoplasmic Membrane ◽  
Membrane Lipids ◽  
Rhizobium Meliloti ◽  
Root Nodules ◽  
Reducing Power ◽  
Spin Resonance ◽  
And Function

Differentiation of Rhizobium meliloti cells in alfalfa root nodules is characterized by alteration in the lipid composition and physical properties of the bacteroid cytoplasmic membrane. Nitrogen-fixing bacteroids isolated from nodules showed an altered phospholipid and fatty acid composition and lacked aliphatic alcohols normally associated with the bacterial cell wall. Bacteroid cytoplasmic membrane lipids were more fluid, but responded specifically to the presence of calcium ion with an increase in the ordered packing of fatty acid side chains, as determined from electron spin resonance spectra of spin probes intercalated in the membrane. This cation also specifically enhanced rates of respiration of the bacteroids and rates of reduction of the spin probe. Bacteroid cytoplasmic membranes differed from those of air-grown cells, both in the amount of cytochromes b and c per cell and in the nature of the terminal oxidase. Cytochrome aa3, was present in bacteroids at less than 1/10 the level found in air-grown cells. The observed differences in the structure and function of the cytoplasmic membrane of bacteroids may be associated with requirements of the bacterial symbiont for utilization of carbon substrates and provision of reducing power in support of the nitrogenase enzyme system which is expressed in the nodule environment.

Effects of Electron Beam on Structure and Physical Properties of Natural Colorless Topaz

2015 ◽  
Vol 1125 ◽  
pp. 60-63
Author(s):  
Chutharat Paikaew ◽  
Juthamas Inthanont ◽  
Adisak Punyanut ◽  
Ekachai Hoonnivathana ◽  
Pichet Limsuwan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Beam ◽  
Physical Properties ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spin Resonance ◽  
Function Group ◽  
And Function ◽  
Beam Dose

The purpose of this research was to investigate physical properties, configuration and color of topaz. Topazes were irradiated with electron beam linear accelerator at different dose from 40 to 180 MGy. The color of topaz was analyzed by UV-vis and it was shown that the color of topaz was becoming strong color with increased electron beam dose. Crystal structure and function group of topaz were characterized by X- ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The results showed that the topaz has orthorhombic structure and no other crystalline. After irradiated, topaz released OH indicating higher crystallinity of topaz and this was confirmed with the results of electron spin resonance (ESR). Electron beam dose response of topaz was investigated. ESR results showed that the Al3+ ion was substituted in Si4+ site and Ti3+ impurity in Al4+ site and this result corresponds to the results of FTIR. The experiment result indicated that electron beam could be making defect on crystal structure and color enhancement of topaz.

scholarly journals Lipid composition of the isolated rat intestinal microvillus membrane

1968 ◽  
Vol 109 (1) ◽  
pp. 51-59 ◽  
Author(s):  
G. G. Forstner ◽  
K. Tanaka ◽  
K. J. Isselbacher
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Neutral Lipid ◽  
Lipid Composition ◽  
Plasma Membranes ◽  
Membrane Lipids ◽  
Saturated Fatty Acids ◽  
Polar Lipids ◽  
Published Data ◽  
Microvillus Membrane

1. Rat intestinal microvillus plasma membranes were prepared from previously isolated brush borders and the lipid composition was analysed. 2. The molar ratio of cholesterol to phospholipid was greatest in the membranes and closely resembled that reported for myelin. 3. Unesterified cholesterol was the major neutral lipid. However, 30% of the neutral lipid fraction was accounted for by glycerides and fatty acid. 4. Five phospholipid components were identified and measured, including phosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, sphingomyelin and lysophosphatidylcholine. Though phosphatidylethanolamine was the chief phospholipid, no plasmalogen was detected. 5. In contrast with other plasma membranes in the rat, the polar lipids of the microvillus membrane were rich in glycolipid. The cholesterol:polar lipid (phospholipid+glycolipid) ratio was about 1:3 for the microvillus membrane. Published data suggest that this ratio resembles that of the liver plasma membrane more closely than myelin or the erythrocyte membrane. 6. The fatty acid composition of membrane lipids was altered markedly by a single feeding of safflower oil. Membrane polar lipids did not contain significantly more saturated fatty acids than cellular polar lipids. Differences in the proportion of some fatty acids in membrane and cellular glycerides were noted. These differences may reflect the presence of specific membrane glycerides.

scholarly journals Fatty Acid Components of Ovine Erythrocyte Lipids

1965 ◽  
Vol 18 (2) ◽  
pp. 445 ◽  
Author(s):  
JM Connellan ◽  
CJ Masters
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Lipid Metabolism ◽  
Structure Function ◽  
Lipid Composition ◽  
Mammalian Erythrocyte ◽  
Mammalian Tissues ◽  
Membrane Type ◽  
And Function ◽  
Erythrocyte Lipids

As part of a study of comparative lipid metabolism, the distribution of fatty acids has been investigated in a number of mammalian tissues (Horgan and Masters 1963; Masters 1964a, 1964b, 1964c; Connellan and Masters 1965), a major aim of these studies being to facilitate correlation between lipid composition and function. In this context, it is widely recognized that membranes playa fundamental role in cellular metabolism, and that lipid is an essential component of these biomembranes (Stein and Danielli 1956). The study of structure-function relationships in this situation, however, has been hindered by the difficulty of isolating specific membranes without contamination by other lipids. The mature mammalian erythrocyte possesses advantageous characteristics for this type of investigation because of the lack of sub-cellular particles, and the resultant presence of only a single membrane type (Kogl et al. 1960). As an extension of previous investigations, then, the fatty acid composi-tion of ovine erythrocytes has been determined.

scholarly journals Lipids in Pathophysiology and Development of the Membrane Lipid Therapy: New Bioactive Lipids

Membranes ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 919
Author(s):  
Manuel Torres ◽  
Sebastià Parets ◽  
Javier Fernández-Díaz ◽  
Roberto Beteta-Göbel ◽  
Raquel Rodríguez-Lorca ◽  
...  
Keyword(s):  
Lipid Bilayer ◽  
Lipid Composition ◽  
Membrane Lipids ◽  
Therapeutic Potential ◽  
Membrane Lipid ◽  
Fatty Acyl ◽  
Bioactive Lipids ◽  
Membrane Lipid Composition ◽  
Membrane Structure And Function ◽  
And Function

Membranes are mainly composed of a lipid bilayer and proteins, constituting a checkpoint for the entry and passage of signals and other molecules. Their composition can be modulated by diet, pathophysiological processes, and nutritional/pharmaceutical interventions. In addition to their use as an energy source, lipids have important structural and functional roles, e.g., fatty acyl moieties in phospholipids have distinct impacts on human health depending on their saturation, carbon length, and isometry. These and other membrane lipids have quite specific effects on the lipid bilayer structure, which regulates the interaction with signaling proteins. Alterations to lipids have been associated with important diseases, and, consequently, normalization of these alterations or regulatory interventions that control membrane lipid composition have therapeutic potential. This approach, termed membrane lipid therapy or membrane lipid replacement, has emerged as a novel technology platform for nutraceutical interventions and drug discovery. Several clinical trials and therapeutic products have validated this technology based on the understanding of membrane structure and function. The present review analyzes the molecular basis of this innovative approach, describing how membrane lipid composition and structure affects protein-lipid interactions, cell signaling, disease, and therapy (e.g., fatigue and cardiovascular, neurodegenerative, tumor, infectious diseases).

scholarly journals In Vitro Resistance of Staphylococcus aureus to Thrombin-Induced Platelet Microbicidal Protein Is Associated with Alterations in Cytoplasmic Membrane Fluidity

2000 ◽  
Vol 68 (6) ◽  
pp. 3548-3553 ◽  
Author(s):  
Arnold S. Bayer ◽  
Rajendra Prasad ◽  
Jyotsna Chandra ◽  
Anjni Koul ◽  
M. Smriti ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Membrane ◽  
Membrane Fluidity ◽  
Cytoplasmic Membrane ◽  
Membrane Lipids ◽  
Serial Passage ◽  
Membrane Structure And Function ◽  
Platelet Microbicidal Protein ◽  
And Function

ABSTRACT Platelet microbicidal proteins (PMPs) are small, cationic peptides which possess potent microbicidal activities against common bloodstream pathogens, such as Staphylococcus aureus. We previously showed that S. aureus strains exhibiting resistance to thrombin-induced PMP (tPMP-1) in vitro have an enhanced capacity to cause human and experimental endocarditis (T. Wu, M. R. Yeaman, and A. S. Bayer, Antimicrob. Agents Chemother. 38:729–732, 1994; A. S. Bayer et al., Antimicrob. Agents Chemother. 42:3169–3172, 1998; V. K. Dhawan et al., Infect. Immun. 65:3293–3299, 1997). However, the mechanisms mediating tPMP-1 resistance in S. aureus are not fully delineated. The S. aureus cell membrane appears to be a principal target for the action of tPMP-1. To gain insight into the basis of tPMP-1 resistance, we compared several parameters of membrane structure and function in three tPMP-1-resistant (tPMP-1r) strains and their genetically related, tPMP-1-susceptible (tPMP-1s) counterpart strains. The tPMP-1rstrains were derived by three distinct methods: transposon mutagenesis, serial passage in the presence of tPMP-1 in vitro, or carriage of a naturally occurring multiresistance plasmid (pSK1). All tPMP-1r strains were found to possess elevated levels of longer-chain, unsaturated membrane lipids, in comparison to their tPMP-1s counterparts. This was reflected in corresponding differences in cell membrane fluidity in the strain pairs, with tPMP-1r strains exhibiting significantly higher degrees of fluidity as assessed by fluorescence polarization. These data provide further support for the concept that specific alterations in the cytoplasmic membrane of S. aureus strains are associated with tPMP-1 resistance in vitro.

scholarly journals Erythrocyte Membrane Lipids in Fríedreich's Ataxia

1979 ◽  
Vol 6 (2) ◽  
pp. 291-294 ◽  
Author(s):  
P. Draper ◽  
Y.S. Huang ◽  
D. Shapcott ◽  
B. Lemieux ◽  
M. Brennan ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Lipid Composition ◽  
Membrane Lipids ◽  
Fatty Acid Distribution ◽  
Friedreich’S Ataxia ◽  
Friedreich's Ataxia ◽  
Erythrocyte Membranes ◽  
Phospholipid Classes ◽  
Membrane Components ◽  
And Control

SummaryIn a study of the lipid composition of erythrocyte membranes in Friedreich's ataxia, the concentration of the major membrane components (phosr pholipids, cholesterol and protein) in ataxie patients, family members, and control subjects were found to be the same. The total fatty acid distribution was also normal. However, an altered distribution of phospholipid classes in erythrocytes was noted (an increase of PI + PS and a decrease of P E in Friedreich's ataxia patients).

The roles of the diversity of amphipathic lipids in shaping membranes by membrane-shaping proteins

2020 ◽  
Vol 48 (3) ◽  
pp. 837-851
Author(s):  
Manabu Kitamata ◽  
Takehiko Inaba ◽  
Shiro Suetsugu
Keyword(s):  
Fatty Acid ◽  
Lipid Composition ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Membrane Lipids ◽  
Cell Types ◽  
Cellular Lipid ◽  
Head Groups ◽  
Packing Defects ◽  
Membrane Bending

Lipid compositions of cells differ according to cell types and intracellular organelles. Phospholipids are major cell membrane lipids and have hydrophilic head groups and hydrophobic fatty acid tails. The cellular lipid membrane without any protein adapts to spherical shapes, and protein binding to the membrane is thought to be required for shaping the membrane for various cellular events. Until recently, modulation of cellular lipid membranes was initially shown to be mediated by proteins recognizing lipid head groups, including the negatively charged ones of phosphatidylserine and phosphoinositides. Recent studies have shown that the abilities of membrane-deforming proteins are also regulated by the composition of fatty acid tails, which cause different degrees of packing defects. The binding of proteins to cellular lipid membranes is affected by the packing defects, presumably through modulation of their interactions with hydrophobic amino acid residues. Therefore, lipid composition can be characterized by both packing defects and charge density. The lipid composition regarding fatty acid tails affects membrane bending via the proteins with amphipathic helices, including those with the ArfGAP1 lipid packing sensor (ALPS) motif and via membrane-deforming proteins with structural folding, including those with the Bin–Amphiphysin–Rvs167 (BAR) domains. This review focuses on how the fatty acid tails, in combination with the head groups of phospholipids, affect protein-mediated membrane deformation.

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