The atypical cell wall composition of Thermomicrobium roseum

1980 ◽  
Vol 26 (4) ◽  
pp. 556-559 ◽  
Author(s):  
G. J. Merkel ◽  
D. R. Durham ◽  
J. J. Perry

The cell wall of Thermomicrobium roseum, a Gram-negative, obligately thermophilic bacterium, has a composition unlike other Gram-negative thermophilic organisms. The purified cell wall was composed predominantly of a protein with a monomeric molecular weight of 75 000. The amino acid composition of this protein revealed high concentrations of proline, glutamic acid, glycine, and alanine.

1968 ◽  
Vol 109 (3) ◽  
pp. 419-432 ◽  
Author(s):  
R. Sentandreu ◽  
D. H. Northcote

1. Glycopeptides containing mannose were extracted from isolated yeast cell walls by ethylenediamine and purified by treatment with Pronase and fractionation on a Sephadex column. 2. A glycopeptide that appeared homogeneous on electrophoresis and ultracentrifugation had a molecular weight of 76000, and contained a high-molecular-weight mannan and approx. 4% of amino acids. 3. The amino acid composition of the peptide was determined. It was rich in serine and threonine and also contained glucosamine. No cystine and methionine were detected. 4. The glycopeptide underwent a β-elimination reaction when treated with dilute alkali at low temperatures. The reaction resulted in the release of mannose, mannose disaccharides and possibly other low-molecular-weight mannose oligosaccharides. During the β-elimination reaction the dehydro derivatives of serine and threonine were formed. One of the linkages between carbohydrate and amino acids in the glycopeptide is an O-mannosyl bond from mannose and mannose oligosaccharides to serine and threonine. 5. After the β-elimination reaction the bulk of the mannose in the form of the large mannan component was still covalently linked to the peptide. This polysaccharide was therefore attached to the amino acids by a linkage different from the O-mannosyl bonds to serine and threonine that attach the low-molecular-weight sugars. 6. Mannan was prepared from the glycopeptide and from the yeast cell wall by treatment of the fractions with hot solutions of alkali. The mannan contained aspartic acid and glucosamine and some other amino acids. The aspartic acid and glucosamine were present in equimolar amounts; the aspartic acid was the only amino acid present in an amount equivalent to that of glucosamine. Thus there is the possibility of a linkage between the mannan and the peptide via glucosamine and aspartic acid. 7. Mannose 6-phosphate was shown to be part of the mannan structure. Information about the structure of the mannan and the linkage of the glucosamine was obtained by periodate oxidation studies. 8. The glucosamine present in the glycopeptide could not be released by treatment with an enzyme preparation obtained from the gut of Helix pomatia. This enzyme released glucosamine from the intact cell wall. Thus there are probably at least two polymers containing glucosamine in the cell wall. 9. The biosynthesis of the mannan polymer in the yeast cell wall is discussed with regard to the two types of carbohydrate–amino acid linkages found in the glycoprotein.


1990 ◽  
Vol 115 (2) ◽  
pp. 281-287 ◽  
Author(s):  
Yong-Soo Hwang ◽  
D.J. Huber ◽  
L.G. Albrigo

Cell wall composition and structure were examined in visually normal (N), granulated (G), and collapsed (VC) juice vesicles of `Marsh Seedless' grapefruit (Citrus paradisi) Macf.). According to gel-filtration data, VC appeared to be associated with a modification of water-soluble (WSP) and chelate-soluble (CSP) pectin molecular weight (Mr); small-Mr pectins increased, whereas large-J4. pectins decreased. The difference in M= of pectins did not appear to be mediated by polygalacturonases. Molecular weight of hemicelluloses did not differ. Granulated vesicles contained about two times more structural polysaccharides (pectins, hemicelhdose, and cellulose) than N vesicles, although hemicellulose and pectin M= modification were absent. Ion-exchange profiles of WSP, CSP, and hemicelhrlose fractions of VC and G vesicles were not different from those of N vesicles. Individual cells in vesicles with G and these vesicles themselves were much larger than those of N vesicles, whereas cells in VC were partially or completely collapsed.


1995 ◽  
Vol 120 (6) ◽  
pp. 1057-1062 ◽  
Author(s):  
D.M. Dawson ◽  
C.B. Watkins ◽  
L.D. Melton

Cell wall changes in `Fantasia' nectarines [Prunus persica (L) Batsch var. nectarina (Ait) maxim] were determined after storage at 0C with or without intermittent warming (at 20C at 2-week intervals) and after ripening. For comparison, fruit were examined at harvest and after ripening without storage. Fruit stored continuously at 0C for 6 weeks became mealy during ripening, whereas fruit subjected to intermittent warming ripened normally. Ripening immediately after harvest was associated with solubilization and subsequent depolymerization of pectic polymers and a net loss of galactosyl residues from the cell wall. No solubilization of pectic polymers from the cell wall occurred during storage of fruit at 0C. Mealy fruit, ripened after continuous storage at 0C, showed only limited solubilization of pectins and depolymerization, high relative molecular weight (M) polymers being predominant. During ripening after storage, pectic polymer solubilization was not as extensive in intermittently warmed fruit as in fruit undergoing normal ripening but solubilized polymers were depolymerized, low M uronic acid-rich polymers becoming predominant. Intermittent warming of fruit resulted in significant softening during storage, alleviating the development of mealiness by promotion of cell wall changes associated with normal ripening.


1969 ◽  
Vol 15 (6) ◽  
pp. 587-594 ◽  
Author(s):  
Janice M. Vickerstaff ◽  
Barry C. Cole

The genital tract bacteria, previously classified as Haemophilus vaginalis and Corynebacterium cervicis and their suggested variant forms, have been characterized by morphology, physiology, and cell wall composition. The strains of H. vaginalis did not form a homogeneous taxonomic group. Only the Dingham strain of Amies and Jones and a Gram-negative culture of strain GP2 of Edmunds were related to the genus Haemophilus. H. vaginalis strain GP7 and the Gram-positive culture of GP2 were corynebacteria. The remaining strains of H. vaginalis were distinct from each other and from the Haemophilus group. None of the strains of C. cervicis could be identified with the genus Corynebacterium. The O strains of C. cervicis were related to the genus Haemophilus, whereas the T strains of C. cervicis and the NCTC strain of H. vaginalis (10287) shared properties with Actinomyces bovis. The two diphtheroids D5 and D17 from a culture of Mycoplasma hominis type 2 (Mycoplasma arthritidis) were dissimilar to each other; D17 was a typical Corynebacterium, whereas D5 was unrelated to the corynebacteria, but similar to the T strains of C. cervicis.


2006 ◽  
Vol 72 (10) ◽  
pp. 6483-6492 ◽  
Author(s):  
Jürgen Behr ◽  
Michael G. Gänzle ◽  
Rudi F. Vogel

ABSTRACT Resistance to hops is a prerequisite for lactic acid bacteria to spoil beer. In this study we analyzed mechanisms of hop resistance of Lactobacillus brevis at the metabolism, membrane physiology, and cell wall composition levels. The beer-spoiling organism L. brevis TMW 1.465 was adapted to high concentrations of hop compounds and compared to a nonadapted strain. Upon adaptation to hops the metabolism changed to minimize ethanol stress. Fructose was used predominantly as a carbon source by the nonadapted strain but served as an electron acceptor upon adaptation to hops, with concomitant formation of acetate instead of ethanol. Furthermore, hop adaptation resulted in higher levels of lipoteichoic acids (LTA) incorporated into the cell wall and altered composition and fluidity of the cytoplasmic membrane. The putative transport protein HitA and enzymes of the arginine deiminase pathway were overexpressed upon hop adaptation. HorA was not expressed, and the transport of hop compounds from the membrane to the extracellular space did not account for increased resistance to hops upon adaptation. Accordingly, hop resistance is a multifactorial dynamic property, which can develop during adaptation. During hop adaptation, arginine catabolism contributes to energy and generation of the proton motive force until a small fraction of the population has established structural improvements. This acquired hop resistance is energy independent and involves an altered cell wall composition. LTA shields the organism from accompanying stresses and provides a reservoir of divalent cations, which are otherwise scarce as a result of their complexation by hop acids. Some of the mechanisms involved in hop resistance overlap with mechanisms of pH resistance and ethanol tolerance and as a result enable beer spoilage by L. brevis.


2019 ◽  
Author(s):  
Margaret Worthington ◽  
Juan Guillermo Perez ◽  
Saule Mussurova ◽  
Alexander Silva-Cordoba ◽  
Valheria Castiblanco ◽  
...  

ABSTRACTToxic concentrations of aluminium cations and low phosphorus availability are the main yield-limiting factors in acidic soils, which represent half of the potentially available arable land. Brachiaria grasses, which are commonly sown as a forage in the tropics because of their resilience and low demand for nutrients, have a greater tolerance to high concentrations of aluminium cations than most other grass crops. In this work, we explored the natural variation in tolerance to aluminium cations (Al3+) between high and low tolerant Brachiaria species and characterised their transcriptional differences during stress. We also identified three QTLs associated with root vigour during Al3+ stress in their hybrid progeny. By integrating these results with a new Brachiaria reference genome, we have identified 30 genes responsible for Al3+ tolerance in Brachiaria. We also observed differential expression during stress of genes involved in RNA translation, response signalling, cell wall composition and vesicle location genes homologous to aluminium-induced proteins involved in limiting uptake or localizing the toxin. However, there was limited regulation of malate transporters in Brachiaria, which are associated with external tolerance mechanisms to Al3+ stress in other grasses. The contrasting regulation of RNA translation and response signalling suggests response phasing is critical to Al3+ tolerance.HIGHLIGHTWe identified QTLs, genes and molecular responses in high and low tolerant Brachiaria grasses associated with aspects of response to aluminium stress, such as regulation, cell-wall composition and active transport.


1975 ◽  
Vol 21 (12) ◽  
pp. 2039-2047 ◽  
Author(s):  
P. F. Winter ◽  
E. A. Delwiche

The cell wall of Veillonella alcalescens was shown to have a typically Gram-negative appearance and composition. The wall contains 24% lipid, 0.8% phosphorus, and 6.8% hexosamine. It is estimated to contain about 5% murein, unlike the 24% reported by other for Veillonella parvula. The amounts of 19 amino acids, including diaminopimelic acid, were determined. Though Veillonella sp. cannot metabolize sugars for energy, V. alcalescens incorporates ribose and fructose by separate, specific mechanisms and uses most of the incorporated sugar in nucleic acid synthesis. Large excesses of either sugar in the medium do not repress gluconeogenesis from the pyruvate level. We have been unable to detect phosphoglyceromutase (EC 2.7.5.3) by several assay methods but have no indication of a gluconeogenic pathway other than reverse glycolysis.


Author(s):  
B.K. Ghosh

Periplasm of bacteria is the space outside the permeability barrier of plasma membrane but enclosed by the cell wall. The contents of this special milieu exterior could be regulated by the plasma membrane from the internal, and by the cell wall from the external environment of the cell. Unlike the gram-negative organism, the presence of this space in gram-positive bacteria is still controversial because it cannot be clearly demonstrated. We have shown the importance of some periplasmic bodies in the secretion of penicillinase from Bacillus licheniformis.In negatively stained specimens prepared by a modified technique (Figs. 1 and 2), periplasmic space (PS) contained two kinds of structures: (i) fibrils (F, 100 Å) running perpendicular to the cell wall from the protoplast and (ii) an array of vesicles of various sizes (V), which seem to have evaginated from the protoplast.


1989 ◽  
Vol 61 (03) ◽  
pp. 437-441 ◽  
Author(s):  
Cindra Condra ◽  
Elka Nutt ◽  
Christopher J Petroski ◽  
Ellen Simpson ◽  
P A Friedman ◽  
...  

SummaryThe present work reports the discovery and charactenzation of an anticoagulant protein in the salivary gland of the giant bloodsucking leech, H. ghilianii, which is a specific and potent inhibitor of coagulation factor Xa. The inhibitor, purified to homogeneity, displayed subnanomolar inhibition of bovine factor Xa and had a molecular weight of approximately 15,000 as deduced by denaturing SDS-PAGE. The amino acid sequence of the first 43 residues of the H. ghilianii derived inhibitor displayed a striking homology to antistasin, the recently described subnanomolar inhibitor of factor Xa isolated from the Mexican leech, H. officinalis. Antisera prepared to antistasin cross-reacted with the H. ghilianii protein in Western Blot analysis. These data indicate that the giant Amazonian leech, H. ghilianii, and the smaller Mexican leech, H. officinalrs, have similar proteins which disrupt the normal hemostatic clotting mechanisms in their mammalian host’s blood.


1979 ◽  
Vol 42 (05) ◽  
pp. 1652-1660 ◽  
Author(s):  
Francis J Morgan ◽  
Geoffrey S Begg ◽  
Colin N Chesterman

SummaryThe amino acid sequence of the subunit of human platelet factor 4 has been determined. Human platelet factor 4 consists of identical subunits containing 70 amino acids, each with a molecular weight of 7,756. The molecule contains no methionine, phenylalanine or tryptophan. The proposed amino acid sequence of PF4 is: Glu-Ala-Glu-Glu-Asp-Gly-Asp-Leu-Gln-Cys-Leu-Cys-Val-Lys-Thr-Thr-Ser- Gln-Val-Arg-Pro-Arg-His-Ile-Thr-Ser-Leu-Glu-Val-Ile-Lys-Ala-Gly-Pro-His-Cys-Pro-Thr-Ala-Gin- Leu-Ile-Ala-Thr-Leu-Lys-Asn-Gly-Arg-Lys-Ile-Cys-Leu-Asp-Leu-Gln-Ala-Pro-Leu-Tyr-Lys-Lys- Ile-Ile-Lys-Lys-Leu-Leu-Glu-Ser. From consideration of the homology with p-thromboglobulin, disulphide bonds between residues 10 and 36 and between residues 12 and 52 can be inferred.


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