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PubMed1983

Spatial differentiation in photosynthetic and non-photosynthetic membranes of Rhodopseudomonas palustris.

The cytoplasmic membrane and the photosynthetic intracytoplasmic membranes of Rhodopseudomonas palustris are spatially differentiated into regions of extremely high intramembrane-particle density (4,400 to 9,800/micron 2) and areas of lower intramembrane-particle density (2,700 to 5,900/micron 2). The high intramembrane-particle-density areas were always seen in association with photosynthetic membrane stacks. This differentiation was also seen in those areas of the cytoplasmic membrane which adhere to the underlying intracytoplasmic membranes, implying that the cytoplasmic membrane too is differentiated for photosynthesis in these regions. Changes in intramembrane-particle size distribution in response to changes in light intensity during growth were measured. We found that, as light levels were decreased from 8,500 to 100 lx, the average particle diameter in the protoplasmic face of stacked intracytoplasmic and cytoplasmic membranes increased from 8.6 to 10.3 nm. We also observed a distinct periodicity in the sizes of the intramembrane particles found in the stacked regions--7.5, 10.0, 12.5, and 15.0 nm--with the larger-size peaks becoming more pronounced as light intensity decreased. This suggests that, as light levels decrease, subunits of discrete size are being added to a core particle. A comparison of propane jet-frozen cells versus fixed, glycerinated, and then frozen cells indicated that ultrarapid freezing leads to a higher quality of fine-structure preservation than does chemical fixation followed by glycerination and conventional freezing in Freon-12 or propane. The intramembrane particles appeared to be more regular in size, lacking the deformed or jagged appearance displayed in fixed preparations.

Bacterial Proteins↗
PubMed1994

Isolation of the outer membranes from Treponema pallidum and Treponema vincentii.

The outer membranes from Treponema pallidum subsp. pallidum and Treponema vincentii were isolated by a novel method. Purified outer membranes from T. pallidum and T. vincentii following sucrose gradient centrifugation banded at 7 and 31% (wt/wt) sucrose, respectively. Freeze fracture electron microscopy of purified membrane vesicles from T. pallidum and T. vincentii revealed an extremely low density of protein particles; the particle density of T. pallidum was approximately six times less than that of T. vincentii. The great majority of T. vincentii lipopolysaccharide was found in the outer membrane preparation. The T. vincentii outer membrane also contained proteins of 55 and 65 kDa. 125I-penicillin V labeling demonstrated that t. pallidum penicillin-binding proteins were found exclusively with the protoplasmic cylinders and were not detectable with purified outer membrane material, indicating the absence of inner membrane contamination. Isolated T. pallidum outer membrane was devoid of the 19-kDa 4D protein and the normally abundant 47-kDa lipoprotein known to be associated with the cytoplasmic membrane; only trace amounts of the periplasmic endoflagella were detected. Proteins associated with the T. pallidum outer membrane were identified by one- and two-dimensional electrophoretic analysis using gold staining and immunoblotting. Small amounts of strongly antigenic 17- and 45-kDa proteins were detected and shown to correspond to previously identified lipoproteins which are found principally with the cytoplasmic membrane. Less antigenic proteins of 65, 31 (acidic pI), 31 (basic pI), and 28 kDa were identified. Compared with whole-organism preparations, the 65- and the more basic 31-kDa proteins were found to be highly enriched in the outer membrane preparation, indicating that they may represent the T. pallidum rare outer membrane proteins. Reconstitution of solubilized T. pallidum outer membrane into lipid bilayer membranes revealed porin activity with two estimated channel diameters of 0.35 and 0.68 nm based on the measured single-channel conductances in 1 M KCl of 0.40 and 0.76 nS, respectively.

Animals↗
PubMed1995

Porin activity and sequence analysis of a 31-kilodalton Treponema pallidum subsp. pallidum rare outer membrane protein (Tromp1).

We have recently reported the isolation and purification of the Treponema pallidum outer membrane and the identification of its rare protein constituents, including a 31-kDa protein markedly enriched in the outer membrane preparation (D.R. Blanco, K. Reimann, J. Skare, C.I. Champion, D. Foley, M. M. Exner, R. E. W. Hancock, J. N. Miller, and M. A. Lovett, J. Bacteriol. 176:6088-6099, 1994). In this study, we report the cloning, sequencing, and expression of the structural gene which encodes the 31-kDa outer membrane protein, designated Tromp1. The deduced amino acid sequence from the tromp1 gene sequence encodes a 318-amino-acid polypeptide with a putative 40-amino-acid signal peptide. Processing of Tromp1 results in a mature protein with a predicted molecular mass of 30,415 Da and a calculated pI of 6.6. Secondary-structure predictions identified repeated stretches of amphipathic beta-sheets typical of outer membrane protein membrane-spanning sequences. A topological model of Tromp1 containing 14 transmembrane segments is proposed. Specific antiserum against a recombinant Tromp1 fusion protein was generated and was used to identify native Tromp1 in cellular fractionation. Upon Triton X-114 extraction and phase separation of T. pallidum, the 31-kDa Tromp1 protein was detected in the detergent-phase fraction but not in the protoplasmic cylinder or aqueousphase fractions, consistent with a hydrophobic outer membrane protein. Anti-Tromp1 antiserum was also used to identify native Tromp1 purified from whole T. pallidum by Triton X-100 solubilization followed by nondenaturing isoelectric focusing. Reconstitution of purified Tromp1 into planar lipid bilayers showed porin activity based on the measured single channel conductanes of 0.15 and 0.7 nS in 1 M KCl. These findings demonstrate that Tromp1 is a transmembrane outer membrane porin protein of T. pallidum.

Amino Acid Sequence↗
PubMed1996

Structural analysis of the Leptospiraceae and Borrelia burgdorferi by high-voltage electron microscopy.

Spirochetes are an evolutionary and structurally unique group of bacteria. Outermost is a membrane sheath (OS), and within this sheath are the protoplasmic cell cylinder (PC) and periplasmic flagella (PFs). The PFs are attached at each end of the PC and, depending on the species, may or may not overlap in the center of the cell. The precise location of the PFs within the spirochetal cells is unknown. The PFs could lie along the cell axis. Alternatively, the PFs could wrap around the PC in either a right- or a left-handed sense. To understand the factors that cause the PFs to influence cell shape and allow the cells to swim, we determined the precise location of the PFs in the Leptospiraceae (Leptonema illini) and Borrelia burgdorferi. Our approach was to use high-voltage electron microscopy and analyze the three-dimensional images obtained from thick sections of embedded cells. We found that a single PF in L. illini is located in a central channel 29 nm in diameter running along the helix axis of the right-handed PC. The presence of the PFs is associated with the end being hook shaped. The results obtained agree with the current model of Leptospiraceae motility. In B. burgdorferi, which forms a flattened wave, the relationship between the PFs and the PC is more complicated. A multistrand ridge 67 nm in diameter, which was shown to be composed of PFs by cross-sectional and mutant analysis, was found to extend along the entire length of the cell. We found that the PFs wrapped around the PC in a right-handed sense. However, the PFs formed a left-handed helix in space. The wavelength of the cell body and the helix pitch of the PFs were found to be identical (2.83 microm). The results obtained were used to propose a model of B. burgdorferi motility whereby backward-propagating waves, which gyrate counterclockwise as viewed from the back of the cell, are generated by the counterclockwise rotation of the internal PFs. Concomitant with this motion, the cell is believed to rotate clockwise about the body axis as shown for the Leptospiraceae.

Borrelia burgdorferi Group↗
PubMed2001

Localization of c-di-GMP-binding protein with the linear terminal complexes of Acetobacter xylinum.

Specific labeling of a single row of cellulose-synthesizing complexes (terminal complexes, TC subunits, TCs, or TC arrays) in Acetobacter xylinum by antibodies raised against a 93-kDa protein (the cyclic dignanylic acid-binding protein) has been demonstrated by using the sodium dodecyl sulfate (SDS)-freeze-fracture labeling (FRL) technique. The antibodies to the 93-kDa protein specifically recognized the TC subunits on the protoplasmic fracture (PF) face of the outer membrane in A. xylinum; however, nonlabeled TCs were also observed. Two types of TC subunits (particles or pits) are observed on the PF face of the outer membrane: (i) immunogold-labeled TCs showing a line of depressions (pits) with an indistinct particle array and (ii) nonlabeled TC subunits with a distinct single row of particle arrays. The evidence indicates that the labeling patterns differ with respect to the presence or absence of certain TC subunits remaining attached to the replica after SDS treatment. This suggests the presence of at least two TC components, one in the outer membrane and the other in the cytoplasmic membrane. If the TC component in the outer membrane is preferentially fractured and remains attached to the ectoplasmic fracture face (or outer leaflet) of the outer membrane, subsequent replica formation reveals a pit or depression with positive antibody labeling on the PF face of the outer membrane. If the TC component in the outer membrane remains with the PF face (or inner leaflet) of the outer membrane, the innermost TC component is removed during SDS treatment and labeling does not occur. SDS-FRL of TCs in A. xylinum has enabled us to provide the first topological molecular analysis of component proteins in a cellulose-synthesizing TC structure in a prokaryotic organism.

Bacterial Proteins↗
PubMed1962

Comparison of lipid composition of pleuropneumonia-like and L-type organisms.

Smith, Paul F. (University of Pennsylvania, Philadelphia) and George H. Rothblat. Comparison of pleuropneumonia-like and L-type organisms. J. Bacteriol. 83:500-506. 1962.-The content of total lipid and nonsaponifiable lipid depended upon the type of organism; the greatest amounts were found in pleuropneumonia-like organisms that required cholesterol for growth and in L-1, the L-form of Streptobacillus moniliformis. Decreasing amounts were found in nonsterol-requiring strains of pleuropneumonia-like organisms, the stable L-form of Proteus, salt-requiring L-forms, and finally, the bacterial parents of the L-type organisms. Nonsterol-requiring pleuropneumonia-like organisms could synthesize their own nonsaponifiable lipid, but sterol-requiring strains could not. Ability or inability to synthesize nonsaponifiable lipid was often carried over to the L-type organisms from the bacterial parent. More nonsaponifiable lipid was found in the sedimentable fraction (cell membrane) than in the nonsedimentable fraction (protoplasm) of both pleuropneumonia-like and L-type organisms. None of the nonsaponifiable lipid synthesized by any organism tested appeared to be 3-beta-hydroxy sterol. Differences in ability of various organisms to take up cholesterol and to be lysed by digitonin were established.

Cell Membrane↗
PubMed1962

Characteristics and significance of the physiological patterns accompanying growth limitation.

Baarda, I. F. (Iowa State University, Ames) and W. R. Lockhart. Characteristics and significance of the physiological patterns accompanying growth limitation. J. Bacteriol. 84:1085-1093. 1962.-The physiological characteristics of several related strains of Escherichia coli were studied during the transition from exponential growth to stationary phase in defined media with limiting concentrations of the carbon or nitrogen source. The metabolic changes typical of this transition, which often are set in motion before exhaustion of the limiting nutrient has occurred, appear to consist of a series of shifts in the relative emphasis placed on competing reaction sequences leading, respectively, to cell division, protoplasmic synthesis, or cell maintenance. This process of biochemical differentiation has characteristic patterns which are qualitatively distinct for particular limiting nutrients and quantitatively different among strains. Correlation of specific metabolic patterns with the characteristic values of certain growth constants for each strain permits hypotheses concerning the physiological significance of these constants.

Carbon↗
PubMed1963

INTRACELLULAR M PROTEIN OF GROUP A STREPTOCOCCUS.

Fox, Eugene N. (University of Chicago, Chicago, Ill.). Intracellular M protein of group A Streptococcus. J. Bacteriol. 85:536-540. 1963.-A heat-labile M protein antigen in protoplasts of a type 14 strain of group A Streptococcus has been demonstrated in a soluble form in the cytoplasm, and also bound to the protoplasmic membrane. When trypsinized whole cells (from which the M protein on the cell wall had been digested) or protoplasts were extracted with hot HCl, no M protein antigen was detected, although the antigen was routinely extracted from the cell walls of normal streptococci by the hot acid procedure. Various serological techniques, including the use of fluorescein-labeled type-specific antisera, were employed to demonstrate the M antigen in association with the membrane from osmotically lysed protoplasts.

Bacterial Proteins↗
PubMed1964

ULTRASTRUCTURE OF VEILLONELLA AND MORPHOLOGICAL CORRELATION OF AN OUTER MEMBRANE WITH PARTICLES ASSOCIATED WITH ENDOTOXIC ACTIVITY.

Bladen, Howard A. (National Institute of Dental Research, Bethesda, Md.), and Stephan E. Mergenhagen. Ultrastructure of Veillonella and morphological correlation of an outer membrane with particles associated with endotoxic activity. J. Bacteriol. 88:1482-1492. 1964.-Normal, phenol-water extracted, and lysozyme-treated Veillonella cells were embedded in Vestopal W, sectioned, and examined by electron microscopy. Normal cells as well as the phenol-water extract (endotoxin) were examined by negative and positive contrast techniques. In thin sections of normal cells, three separate structural entities were observed surrounding the protoplasm, and were referred to as the outer membrane, the solid membrane, and the plasma membrane. The outer membrane was a membrane composed of two dense layers (30 A) separated by a less-dense layer (20 A), and followed a convoluted and continuous path around the cell. The solid membrane appeared as a taut, dense structure 100 to 500 A wide, and was separated from the outer membrane by up to several hundred Angstroms. The plasma membrane was a unit-type membrane. After cells were treated with phenol-water, the outer membrane was absent, but the cells remained intact owing to the solid membrane. Observation of the phenol-water extract (endotoxin) revealed predominantly circular particles or discs which had approximately the same dimensions in height as the outer membrane had in width. Negatively stained whole cells showed similar structures on their surface. Lysozyme treatment of the cells did not affect the outer membrane; however, the solid membrane became diffuse and often disappeared, suggesting that the outer membrane and the solid membrane were separate structures.

Cell Membrane↗
PubMed1966

Effective nonliving vaccine against experimental tuberculosis in mice.

Ribi, Edgar (Rocky Mountain Laboratory, Hamilton, Mont.), Carl Larson, William Wicht, Robert List, and Granville Goode. Effective nonliving vaccine against experimental tuberculosis in mice. J. Bacteriol. 91:975-983. 1966.-Antituberculosis vaccines were prepared in one of three manners: lyophilized BCG suspended in light mineral oil was disrupted in a Sorvall pressure cell and the "oil disruption product" was collected by centrifugation; BCG was disrupted in water, lyophilized, and worked into a paste with a small amount of oil (about 0.16 ml per 50 mg); BCG was disrupted in water, and the cell wall fraction was isolated, lyophilized, and prepared in an oil paste. These vaccines were suspended in Tween-saline to a concentration of 5 mg/ml and heated at 65 C for 30 min. In protection tests based on pulmonary infection with Mycobacterium tuberculosis H37Rv, the median number of virulent organisms in lung tissue of mice immunized with a few hundred micrograms of these three vaccines was 3 to 4 logs lower than in unvaccinated control mice. A similar dose of viable BCG standard vaccine reduced the lung count 1 to 2 logs below the controls. Protection afforded by nonviable, whole BCG, with or without oil, was of only borderline significance. Since oil-treated fractions containing cell walls produced effective immunity, while the oil-treated protoplasm or whole cells were not active, the protective antigen appeared to be an inner component of the cell wall, exposed when the cell was disrupted, and activated by oil. Extraction of oil from immunogenic disruption products resulted in loss of ability of the products to confer protection against the aerosol challenge, whereas high protection against the conventional challenge by intravenous infection with up to 1.4 x 10(8) cells of M. tuberculosis H37Rv was retained. Retreatment with oil of these nonimmunogenic products restored the immunogenicity if the oil was applied to dried products. The consistent finding that moisture interferes with the enhancement of the vaccine potency by oil suggested that such enhancement may not be the same as that ordinarily produced by water-in-oil emulsions.

Aerosols↗
PubMed1967

Fine structure of quiescent and germinating aeciospores of Cronartium fusiforme.

Aeciospores of the long-cycle heteroecious rust fungus, Cronartium fusiforme, were found to have an extremely thick cell wall with striking spicules protruding from it. The wall was readily degraded by commercial chitinase, but spicules were unaffected. Quiescent spores contained two nuclei with distinct nuclear membranes possessing many pores. Numerous membrane-bounded lipid bodies were found both in wild-type orange and in white mutant aeciospores. An abundance of irregularly ovoid mitochondria was present in quiescent spores. After glutaraldehydeosmium fixation, the surface of the mitochondria appeared to be covered with ribosomes or microtubules in a paracrystalline array, whereas after permanganate fixation only smooth outer mitochondrial membranes were noted. The latter fixative revealed abundant vesicular endoplasmic reticulum in the spore. Spores incubated at 20 C on agar produced one to five distinct germ tubes within 65 to 180 min. These thin-walled tubes exhibited varying degrees of branching, and reached a total hyphal length of 300 to 500 mu prior to rupturing. Emergence of germ tubes took place through a pore in the spore wall and appeared to be mainly a physical flowing of cytoplasm from the spore into the germ tube without division of nuclei or other cell organelles. On completion of germination, the protoplasm of the germ tube contained both nuclei and nearly all of the other spore contents. Mitochondria had smooth outer membranes, were greatly elongated, and possessed distinct longitudinal cristae. A limited amount of rough endoplasmic reticulum was arranged parallel to the germ tube wall. Other organelles seen in germ tubes were lipid bodies, concentric membrane figures, and numerous ribosomes. Lipid bodies appeared smaller and fewer in number than in quiescent spores.

Basidiomycota↗
PubMed1969

Permeability of Serratia marcescens to some inorganic salts.

The physical interactions between Serratia marcescens and solutions of NaCl, CaCl(2), CaI(2), NaI, and Na(2)HPO(4) plus NaH(2)PO(4) were examined. Dilute (0.017 n) salt solutions did not cause cells to lose water, as evidenced by the unchanged weight of centrifugally packed cells. The cells preferentially adsorbed the cations and repelled the anions of most salts in these solutions. Concentrated (1.71 n) salt solutions markedly reduced the weight and water content of centrifugally packed cells, although these cells took up considerable amounts of salts. More than 90% of the water in the packed-cell pellets was available for the solution of NaCl at 4.2 to 4.4% concentration. The observation that salts apparently penetrated the cells freely and yet caused extensive dehydration was not readily compatible with conventional concepts of solute-induced plasmolysis. Alternative hypotheses to explain the data included the following. First, the cells lost weight and water to concentrated salt solutions through a nonosmotic competitive dehydration, causing a shrinkage of the protoplasmic gel. The shrinkage of the cell wall was limited because of the rigidity of its mucopeptide layer; therefore, a space appeared between the cell wall and the cell membrane. Second, cells may have equilibrated their water activity with that of their environment by two mechanisms: (i) the loss of water by plasmolysis or competitive dehydration, and (ii) alterations in cell permeability that admitted previously excluded solutes to the cell interior. Possibly, the correct explanation of the observations reported here involves elements of all three hypotheses, plasmolysis, competitive dehydration, and permeability alterations.

Calcium Chloride↗
PubMed1969

Purification, ultrastructure, and composition of axial filaments from Leptospira.

The ultrastructure of three strains of water Leptospira was studied by negative staining, thin sectioning, and freeze-etching. The cells possessed a triple-layered sheath which covered two independent axial filaments, one inserted subterminally in each end of the cell. The protoplasmic cylinder was surrounded by a triple-layered cell wall and possessed ribosomes, lamellar structures, and a typical procaryotic nuclear region. The axial filament was comprised of several component structures. An axial fibril, with a diameter of 20 to 25 nm, consisted of a solid inner core (13 to 16 nm in diameter) surrounded by a coat. A terminal knob (40 to 70 nm in length) was connected to a series of disc insertion structures at the terminal end of the axial fibril. The axial fibril was surrounded by a helical outer coat (35 to 60 nm in diameter) which was composed of a continuously coiled fiber, 3 to 4 nm in diameter, embedded in an electron-dense material. A procedure for the purification of the axial fibrils was presented and their ultrastructural, physical, and chemical properties were determined. Similarities in ultrastructural, physical, and chemical properties were noted between the axial fibrils and bacterial flagella. A schematic model of the leptospiral axial filament is presented, and a mechanism is proposed for its function as a locomotor organelle.

Amino Acids↗
PubMed1969

Morphological changes of Mycobacterium lepraemurium grown in cultures of mouse peritoneal macrophages.

Studies were made on morphological changes of Mycobacterium lepraemurium grown in cultures of mouse peritoneal macrophages. Two types of nonsolid or irregularly stained M. lepraemurium were observed. One type occurred in the growth phase of the organisms during the stage of preparation for bacillary multiplication. The nonsolid bacilli appeared as elongated organisms having pointed ends, isolated acid-fast dots, or faintly stained areas at the ends of the bacilli. It is possible that this irregularity in staining is due to a very gradual, versus an instantaneous, acquisition of acid-fast material during bacillary multiplication and maturation. Solid forms were again observed upon maturation. Nonsolid bacilli were also observed in macrophage cultures infected with autoclave-killed M. lepraemurium. Under these conditions there was an emergence of organisms which showed irregularly stained areas and various forms of deformity unaccompanied by elongation or multiplication. These irregularities were most probably due to the destructive process of digestion of bacillary protoplasm. The present study does not support the current hypothesis that all nonsolid acid-fast organisms are nonviable.

Animals↗
PubMed1979

New method for estimating digestion of Paracoccidioides brasiliensis by phagocytic cells in vitro.

We describe a method by which phagocytosis and digestion of Paracoccidioides brasiliensis yeast cells by polymorphonuclear leukocytes or other phagocytic cells may be estimated. Suspensions of P. brasiliensis in its yeastlike phase were sonicated, counted, and incubated with known numbers of peripheral blood polymorphonuclear leukocytes. At given intervals, cytocentrifuge droplets were stained by a variation of Papanicolaou's method. Stained preparations were examined with phase-contrast optics. Digested organisms showed total or partial disappearance of protoplasm. Green-stained cell walls resisted digestion. The proportion of digested cells as a function of time was estimated.

Fungi↗
PubMed1993

Isolation and characterization of "Flexispira rappini" from laboratory mice.

A bacterium with an unusual ultrastructure and possessing a fusiform protoplasmic cylinder, spiral periplasmic fibers, and bipolar tufts of sheathed flagella was identified in the intestinal mucosae of laboratory mice. The organism was cultured under microaerophilic conditions and was found to rapidly hydrolyze urea. On the basis of 16S rRNA gene sequence analysis, the organism was shown to be "Flexispira rappini." "F. rappini" is closely related to members of the genus Helicobacter and has been reported to be associated with human gastroenteritis and ovine abortion. "F. rappini" has not previously been observed in the gastrointestinal tracts of mice.

Animals↗
PubMed1968

Adsorption of bacteriophages to adhesions between wall and membrane of Escherichia coli.

In plasmolyzed Escherichia coli, wall and membrane adhered to one another at 200 to 400 localized areas. This number of specialized wall areas per cell was of the same order of magnitude as the total number of bacteriophage receptors. When bacteriophages T1 to T7 were adsorbed to the bacteria, they were seen to attach almost exclusively to these areas. Comparisons of the number of adsorbed phage particles observed in ultrathin sections and the expected number of phages per cell were in agreement. These results suggest a sharing of receptive areas by the various phages. Adsorption to the wall-membrane associations would permit the virus to release its nucleic acid at an area closest to the cell's protoplasmic contents.

Adsorption↗
PubMed1989

Localization of Epstein-Barr virus envelope glycoproteins on the inner nuclear membrane of virus-producing cells.

Epstein-Barr virus-producing cells were used as a model to analyze, with a fracture-immunolabel technique, the distribution, behavior on fracture, and extent of glycosylation of viral transmembrane glycoproteins at the inner nuclear membrane. Surface and fracture immunolabeling with two monoclonal antibodies directed against the carbohydrate or polypeptide portions of the major viral envelope glycoproteins gp350/220 showed the following. (i) The glycoproteins present on the inner and outer nuclear membranes were labeled only with the monoclonal antibody directed against the polypeptide chain, whereas over the surface of virus-producing cells and on mature virions the labeling was dense and uniformly distributed with both monoclonal antibodies. (ii) The glycoproteins were nonuniformly distributed only over the inner nuclear membranes; at the sites of viral budding, the glycoproteins showed a preferential partition with the protoplasmic face. Since fully glycosylated glycoproteins were not present on the nuclear membranes, our observations support the proposed model of herpesvirus maturation. The peculiar distribution and partition on fracture of the envelope glycoproteins on the inner nuclear membrane are similar to those of Sindbis virus envelope glycoproteins on the plasma membrane of infected cells. Therefore, our results suggest that inner nuclear membranes may behave like plasma membranes during viral assembly.

Antigens, Viral↗