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PubMed2002

Microtubule organization in the green kingdom: chaos or self-order?

Plant microtubule arrays differ fundamentally from their animal, fungal and protistan counterparts. These differences largely reflect the requirements of plant composite polymer cell walls and probably also relate to the acquisition of chloroplasts. Plant microtubules are usually dispersed and lack conspicuous organizing centres. The key to understanding this dispersed nature is the identification of proteins that interact with and regulate the spatial and dynamic properties of microtubules. Over the past decade, a number of these proteins have been uncovered, including numerous kinesin-related proteins and a 65 kDa class of structural microtubule-associated proteins that appear to be unique to plants. Mutational analysis has identified MOR1, a probable stabilizer of microtubules that is a homologue of the TOGp-XMAP215 class of high-molecular-weight microtubule-associated proteins, and a katanin p60 subunit homologue implicated in the severing of microtubules. The identification of these two proteins provides new insights into the mechanisms controlling microtubule assembly and dynamics, particularly in the dispersed cortical array found in highly polarized plant cells.

Adenosine Triphosphatases↗
PubMed2000

Friulimicins: novel lipopeptide antibiotics with peptidoglycan synthesis inhibiting activity from Actinoplanes friuliensis sp. nov. I. Taxonomic studies of the producing microorganism and fermentation.

A strain that produces new lipopeptide antibiotics is a new species of the genus Actinoplanes for which we propose the name Actinoplanes friuliensis (type strain: HAG 010964). The strain is an actinoplanete actinomycete having cell wall II composition and forming sporangia. Comparisons with Actinoplanes spp. which have similarities with our isolate, including fatty acid analysis, showed that the isolate belongs to a new species. Taxonomic studies and fermentation are presented.

Actinomycetales↗
PubMed1998

[Studies on actinomycetes population from salt lake of Yuncheng in Shanxi].

120 strain of mesophilic and thermophilic of alkalaphilic actinomycetes of alkalic tolerant actinomycetes isolated from Yuncheng salt lake in Shanxi were identified. On the basis of morphological characteristics and some chemotaxonomic properties (composition of cell wall, whole cell sugar), the isolated strains were classified into Nocadiopsis, Micromonospora, Actinomadura and Streptomyces. The Streptomyces strains were classified into 11 groups.

Actinomycetales↗
PubMed1977

[Chemical composition and degradation of the cells walls of a wild-type and of a white mutant of the mushroom Drechslera sorokiniana].

The cell walls of the fungus Drechslera sorokiniana and an albino mutant have been studied to determine if disappearance of pigment also involves an important modification of the chemical structure. The albino mutant has lost, besides the pigment, pentose, xylose, and part of galactose and mannose. The protein contents as well as those of hexosamine and chitin are not modified. After treatments of the walls with 2 M NaOH-0.5 M H2SO4 and with ethylenediamine identical compounds are isolated from the two walls; however, cell walls of the mutant are more easily and more extensively degraded than those of the wild type. This difference in resistance is not only due to the presence of pigment but also to a different architectural structure of the two cell walls.

Amino Acids↗
PubMedDate not supplied

[The effect of trisporic acids on the composition of components of the cell wall in Blakeslea trispora Thaxter].

The cell wall of Blakeslea trispora was found to contain chitin similar to crustaceaous chitin in physico-chemical properties; this was confirmed by the data of IR spectroscopy and X-ray diffraction analysis. Trisporic acids, hormonal regulators of reproduction, hardly affected the content of chitin, xylan, and other polysaccharides of the cell wall of Blakeslea trispora, but increased the content of protein.

Cell Wall↗
PubMed1984

Role of biotin in the production of lysine by Brevibacterium lactofermentum.

To investigate the role of biotin in lysine production, Brevibacterium lactofermentum ATCC 21086 was grown in an acid-hydrolysed whey permeate medium with and without added biotin. Added biotin stimulated lysine production and growth of B. lactofermentum. Five micrograms of biotin/100 ml was the optimum level of addition. Biotin increased the uptake of 14C-glucose and affected fatty acid composition of cell wall lipids. Cell walls of test organisms contained less 16:0 and more 18:2 fatty acids than did those from control cells. However, biotin did not substantially affect the phospholipid content of cell walls and whole cells, and the intracellular free lysine level. It was concluded that the promotive effect of biotin in lysine production might be due to the stimulatory effect of biotin on the growth of B. lactofermentum. Alteration of the cell surface caused by biotin did not appear to affect the release or accumulation of lysine.

Biotin↗
PubMed1983

Chemical composition and biological functions of Listeria monocytogenes cell wall preparations.

A crude Listeria cell wall fraction, a purified fraction (PF) with demonstrated biological activity, as well as a third fraction of base-hydrolyzed PF (BHPF) were analyzed for chemical composition and activities not previously described. Listeria cell wall fraction and PF contained significant quantities of lipid, whereas BHPF was lipid depleted. Fatty acid compositions were typical of gram-positive bacteria. PF and BHPF were depleted in protein. Alanine, glutamic acid, diaminopimelic acid, glucosamine, and muramic acid were found in all fractions, in enhanced concentration in PF and BHPF, and with molar ratios typical of bacterial peptidoglycans. Major neutral sugars were rhamnose, ribose, ribitol, and glucose. The concentrations of rhamnose, ribose, and glucose were increased in BHPF. Differences in chemical composition of the fractions reflected differences in their biological activities: Listeria cell wall fraction induced resistance to Listeria infection, whereas PF did not. Mitogenic and adjuvant activities were demonstrated for Listeria cell wall fraction and PF but were lost in BHPF. BHPF retained the ability to induce macrophage-mediated tumoricidal activity and decrease resistance to Listeria infection.

Adjuvants, Immunologic↗
PubMed1971

Cell wall polysaccharide biosynthesis by membrane fragments from Streptococcus pyogenes and stabilized L-form.

The formation and composition of a cell wall rhamnose-containing polysaccharide by membrane fragments from Streptococcus pyogenes and its stabilized L-form were compared. Also, the effect of prior treatment on the ability of coccal whole-cell and membrane fragments to incorporate radioactivity from thymidine diphosphate-(14)C-rhamnose, and the results of subsequent attempts to remove labeled polysaccharide from such membranes are given. L-form membrane fragments were capable of only 10% uptake of (14)C-rhamnose from this nucleotide as compared with streptococcal membranes. However, once bound, both membrane fragments polymerized rhamnose to the same extent. These findings tend to negate the almost complete lack of polymeric rhamnose within the intact L-form as being due to the absence of membrane enzymes necessary for the transfer of rhamnose from a suitable precursor to membrane acceptor sites or enzymes responsible for rhamnose polymerization. Degradation of labeled rhamnose polysaccharide after isolation from coccal membranes by mild acid hydrolysis showed muramic acid and glucosamine to be attached. This same polysaccharide from L-form membrane fragments was devoid of amino sugars. These data suggest the possible involvement of amino sugars in the attachment of cell wall polymeric rhamnose to the streptococcal cytoplasmic membrane. The absence of attached amino sugars to rhamnose polysaccharide from L-form membrane fragments is discussed in terms of this organism's continued inability for new cell wall formation. The isolation, from streptococcal membrane fragments, of a polysaccharide containing rhamnose and amino sugars common to at least two different streptococcal cell wall-type polymers was demonstrated.

Amino Sugars↗
PubMed1981

Cell wall modification resulting from in vitro induction of L-phase variants of Nocardia asteroides.

The chemical composition of the cell walls of several L-form revertants derived from Nocardia asteroides 10905 was determined at different stages of growth. It was observed that each L-form revertant had a cell well that differed from that of the parental strain when grown under identical conditions. In some strains the peptidolipid and mycolic acid components were affected the most, whereas in other strains the fatty acid, sugar, and mycolic acid moieties were altered. Shifts in mycolic acid size were prominent, whereas the basic peptidoglycan structure appeared to be affected the least. Both the method used to induce the L-form of N. asteroides 10905 and the length of time these organisms were maintained in the wall-less state affected the degree of cell wall modification during the reversion process. Thus, removal of the cell wall appeared to potentiate and select for mutational alterations within the cell envelope of N. asteroides, and these changes resulted in altered cellular and colonial morphology.

Amino Acids↗
PubMed1985

Antigenic heterogeneity of an alkali-soluble, water-soluble cell wall extract of Coccidioides immitis.

The antigenic composition of an alkali-soluble, water-soluble cell wall extract of Coccidioides immitis, designated C-ASWS, was assessed by two-dimensional immunoelectrophoresis against goat antisera to C-ASWS and coccidioidin. The results established that C-ASWS from mycelia or spherule cell walls is heterogeneous in composition, containing two distinct antigenic components. One is present as a polymer that is antigenically identical to a polymeric antigen in coccidioidin, designated antigen 2. The other component detected in C-ASWS presented an unusual precipitin pattern in that a cathodal leg was demonstrable in the absence of an anodal leg. This incomplete precipitinogen was also detected in coccidioidin. In addition to the finding that C-ASWS is antigenically heterogeneous, the results provide evidence that the conformational and/or configurational structure of the C-ASWS antigen 2 (or antigen 2-like polymer) is altered during physicochemical extraction. This conclusion is based upon the finding that the immunoelectrophoretic profile of the C-ASWS polymer differs from that of coccidioidin antigen 2. The C-ASWS polymer is characterized by having a small cathodal precipitin peak connected to a large anodal peak, whereas coccidioidin antigen 2 is characterized by a predominant cathodal peak.

Antigens, Fungal↗
PubMedDate not supplied

Mannosyltransferase is required for cell wall biosynthesis, morphology and control of asexual development in Neurospora crassa.

Two Neurospora mutants with a phenotype that includes a tight colonial growth pattern, an inability to form conidia and an inability to form protoperithecia have been isolated and characterized. The relevant mutations were mapped to the same locus on the sequenced Neurospora genome. The mutations responsible for the mutant phenotype then were identified by examining likely candidate genes from the mutant genomes at the mapped locus with PCR amplification and a sequencing assay. The results demonstrate that a map and sequence strategy is a feasible way to identify mutant genes in Neurospora. The gene responsible for the phenotype is a putative alpha-1,2-mannosyltransferase gene. The mutant cell wall has an altered composition demonstrating that the gene functions in cell wall biosynthesis. The results demonstrate that the mnt-1 gene is required for normal cell wall biosynthesis, morphology and for the regulation of asexual development.

Amino Acid Sequence↗
PubMedDate not supplied

[Effect of heat shock on the amino acid makeup of the whole cells and walls of Candida utilis yeasts in chemostat cultivation].

The amino acid composition of intact cells and cell walls was determined in Candida utilis AUCMY-1,668 growing in the regime of chemostat with limitation by glycerol or ethanol deficiency at a temperature of 30 degrees C (control) or with inhibition by an elevated temperature of 40 degrees C (experiment). In the control, intact cells contained 43-44% of amino acids, and cell walls, about 10% (per the weight of dry cell walls); the following amino acids prevailed in the cell walls: threonine, glutamic acid, serine and leucine. The content of amino acids decreased in both the intact cells and cell walls at the elevated temperature (40 degrees C). The content of leucine, methionine, tyrosine and cystine decreased in the cell walls more than in the intact cells (with regard to the total amino acid content of the cell walls and intact cells, respectively). Under the action of the elevated temperature, the cells became larger and did not separate: the scar formed at the end of budding stretched between the mother and daughter cells holding them together.

Amino Acids↗
PubMed1989

Physicochemical interaction of Escherichia coli cell envelopes and Bacillus subtilis cell walls with two clays and ability of the composite to immobilize heavy metals from solution.

Isolated Escherichia coli K-12 cell envelopes or Bacillus subtilis 168 cell walls were reacted with smectite or kaolinite clay in distilled deionized water (pH 6.0); unbound envelopes or walls were separated by sucrose density gradient centrifugation, and the extent of adsorption was calculated. At saturation, both clays adsorbed approximately 1.0 mg (dry weight) of envelopes or walls per mg (dry weight) of clay. Clays showed a preference for edge-on orientation with both walls and envelopes, which was indicative of an aluminum polynuclear bridging mechanism between the wall or envelope surface and the clay edge. The addition of heavy metals increased the incidence of planar surface orientations, which suggested that multivalent metal cation bridging was coming into play and was of increasing importance. The metal-binding capacity of isolated envelopes, walls, clays, and envelope-clay or wall-clay mixtures was determined by atomic absorption spectroscopy after exposure to aqueous 5.0 mM Ag+, Cu2+, Cd2+, Ni2+, Pb2+, Zn2+, and Cr3+ nitrate salt solutions at pHs determined by the buffering capacity of wall, envelope, clay, or composite system. The order of metal uptake was walls greater than envelopes greater than smectite clay greater than kaolinite clay for the individual components, and walls plus smectite greater than walls plus kaolinite greater than envelopes plus smectite greater than envelopes plus kaolinite for the mixtures. On a dry-weight basis, the envelope-clay and wall-clay mixtures bound 20 to 90% less metal than equal amounts of the individual components did.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗