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101.
102.
Unusual composition of peptidoglycan in Bordetella pertussis 总被引:3,自引:0,他引:3
E Tuomanen J Schwartz S Sande K Light D Gage 《The Journal of biological chemistry》1989,264(19):11093-11098
The composition of the peptidoglycan of Bordetella pertussis and the nature of its turnover products was determined by a new combination of analytical techniques: high performance liquid chromatography of an enzymatic peptidoglycan hydrolysate and fast atom bombardment mass spectrometry and fast atom bombardment collision-activated dissociation tandem mass spectrometry. Sixteen major components of the peptidoglycan were purified, and assignment of complete or partial chemical structures was achieved for nine and seven species, respectively. At this level of resolution, a previously unrecognized heterogeneity of monomeric (five new species; nine total) and dimeric species (five new species; five total) was detected. No species containing diaminopimelyl-diaminopimelic acid cross-links or lysyl-arginine substitutions were found. Previous estimates of total cross-linkage and average chain length were revised downward to 32% and 21 disaccharide residues, respectively. Detection of a chemically novel species, a disaccharide octapeptide monomer, in both the peptidoglycan hydrolysate and culture supernatant fluid, suggests that an N-acetyl-muramyl-L-alanine amidase acts on the intact peptidoglycan of Bordetella and participates in cell wall turnover. Five peptidoglycan turnover products were identified in the supernatant fluid of late logarithmic phase cultures, including the 1,6-anhydro monomeric species known as tracheal cytotoxin. Peptidoglycan turnover was detected at a low rate of approximately 10%/generation, a value sufficient to account for the generation of all tracheal cytotoxin found in culture supernatant fluids. 相似文献
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Nicholas D. Light 《Biochemical and biophysical research communications》1978,81(2):261-267
Studies reproted here indicate that a major cell surface glycoprotein of the rabbit bone marrow erythroid cell may be involved in binding transferrin. The glycoprotein has an apparent molecular weight of 18,000. It is suggested that bone marrow erythroid cells may provide an invaluable source of the red cell membrane transferrin receptor for future studies. 相似文献
107.
Baer-Lehman ML Light T Fuller NW Barry-Landis KD Kindlin CM Stewart RL 《Experimental & applied acarology》2012,58(3):301-314
Competition among ticks, and among ectoparasites generally, has rarely been demonstrated. Ixodes scapularis and Dermacentor albipictus are both hard ticks commonly found feeding on deer harvested at Letterkenny Army Depot, in south central Pennsylvania, USA. The two species have contrasting life histories resulting in D. albipictus spending notably more time on the shared host. We hypothesized that this would give D. albipictus an advantage in locating and occupying optimal attachment sites (highly vascularized areas like the head and ears). Ticks were collected from 224 hunter-killed deer in December 2005 and November 2006 to determine if there is evidence of competition for attachment sites when these two species concurrently infest deer. A timed sample (3?min per region) of representative ticks was collected from the head (ears, face and neck regions) and body (axillae regions). Ixodes scapularis was more abundant and prevalent overall than D. albipictus. Dermacentor albipictus was found almost exclusively on the head, whereas I. scapularis was more evenly distributed, but somewhat more abundant on the body than on the head. The proportion of I. scapularis on the head was reduced at high D. albipictus abundances, but I. scapularis abundance did not alter the distribution of D. albipictus. This study supports the hypothesis of competition for preferred attachment sites between these two species of ticks, and suggests that D. albipictus may be competitively dominant over I. scapularis on the head region of concurrently infested white-tailed deer. 相似文献
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Light SH Halavaty AS Minasov G Shuvalova L Anderson WF 《Protein science : a publication of the Protein Society》2012,21(6):887-895
3-Deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAHPS) catalyzes the first step in the biosynthesis of a number of aromatic metabolites. Likely because this reaction is situated at a pivotal biosynthetic gateway, several DAHPS classes distinguished by distinct mechanisms of allosteric regulation have independently evolved. One class of DAHPSs contains a regulatory domain with sequence homology to chorismate mutase-an enzyme further downstream of DAHPS that catalyzes the first committed step in tyrosine/phenylalanine biosynthesis-and is inhibited by chorismate mutase substrate (chorismate) and product (prephenate). Described in this work, structures of the Listeria monocytogenes chorismate/prephenate regulated DAHPS in complex with Mn(2+) and Mn(2+) + phosphoenolpyruvate reveal an unusual quaternary architecture: DAHPS domains assemble as a tetramer, from either side of which chorismate mutase-like (CML) regulatory domains asymmetrically emerge to form a pair of dimers. This domain organization suggests that chorismate/prephenate binding promotes a stable interaction between the discrete regulatory and catalytic domains and supports a mechanism of allosteric inhibition similar to tyrosine/phenylalanine control of a related DAHPS class. We argue that the structural similarity of chorismate mutase enzyme and CML regulatory domain provides a unique opportunity for the design of a multitarget antibacterial. 相似文献
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Olivier Peraud Jason S. Biggs Ronald W. Hughen Alan R. Light Gisela P. Concepcion Baldomero M. Olivera Eric W. Schmidt 《Applied and environmental microbiology》2009,75(21):6820-6826
Actinomycetes can be symbionts in diverse organisms, including both plants and animals. Some actinomycetes benefit their host by producing small molecule secondary metabolites; the resulting symbioses are often developmentally complex. Actinomycetes associated with three cone snails were studied. Cone snails are venomous tropical marine gastropods which have been extensively examined because of their production of peptide-based neurological toxins, but no microbiological studies have been reported on these organisms. A microhabitat approach was used in which dissected tissue from each snail was treated as an individual sample in order to explore bacteria in the tissues separately. Our results revealed a diverse, novel, and highly culturable cone snail-associated actinomycete community, with some isolates showing promising bioactivity in a neurological assay. This suggests that cone snails may represent an underexplored reservoir of novel actinomycetes of potential interest for drug discovery.Interest in natural products and drug discovery has been a major driving force for the study of microbial communities associated with marine invertebrates. Sponges, which have provided more bioactive metabolites than any other marine invertebrate group (see reference 4 and previous references in that series) have been the main focus of these investigations, yielding numerous reports of associated bacteria and complex microbial communities (17, 43). Other examples of marine invertebrate-associated microbes explored for their involvement in natural products include bryozoans (9, 41), ascidians (37), and shipworms (46). Thus far, there are literature reports of diverse bacterial taxa involved in natural product biosynthesis in marine animals (9, 10). Notably less well studied are the symbiotic actinomycetes, for which the biology of host-actinomycete associations is just beginning to be explored in a methodical way. Actinomycetes are known to be important symbionts in a number of biological systems, such as plants, insects, and marine invertebrates, contributing as nitrogen fixers in plants (39) or utilizing their chemical arsenal for defense purposes (8, 22, 38).An initial investigation of a cone snail yielded a surprisingly high number of actinomycetes (data not shown), prompting this follow-up study on additional samples. Cone snail mollusks belong to the genus Conus, which contains about 500 closely related species (11). These mollusks are well known for their complex neurologically active venoms that they use to immobilize their prey, including fish, worms, and other mollusks. The venom of cone snails has been extensively studied, but to our knowledge no study of cone snail microbial communities has been reported. Cone snails are part of the larger superfamily Conoidea, comprising ∼20,000 species, making it an extremely diverse group (25, 34). Given the initial observation of cultivable actinomycetes from cone snails, this large group seemed like a potentially excellent source of new bacterial natural products and new models of actinomycete symbiosis.The goal of this study was to examine the actinobacteria community associated with tropical marine snails of the genus Conus, using a microhabitat approach by which individual organs are treated as independent samples, and to assess the bioactivities of the isolates obtained by using a neurological assay. Although similar approaches have previously been used in microbial ecology (3, 42), this is a novel approach in drug discovery for the identification of bioactive bacteria. We report here the association between three cone snails, Conus pulicarius, Conus rolani, and Conus tribblei, and their actinobacteria as well as the bioactivities of some of these actinobacteria. 相似文献