Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FLAGELLATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53Linked to original sources
PubMed2001

The innate immune response to bacterial flagellin is mediated by Toll-like receptor 5.

The innate immune system recognizes pathogen-associated molecular patterns (PAMPs) that are expressed on infectious agents, but not on the host. Toll-like receptors (TLRs) recognize PAMPs and mediate the production of cytokines necessary for the development of effective immunity. Flagellin, a principal component of bacterial flagella, is a virulence factor that is recognized by the innate immune system in organisms as diverse as flies, plants and mammals. Here we report that mammalian TLR5 recognizes bacterial flagellin from both Gram-positive and Gram-negative bacteria, and that activation of the receptor mobilizes the nuclear factor NF-kappaB and stimulates tumour necrosis factor-alpha production. TLR5-stimulating activity was purified from Listeria monocytogenes culture supernatants and identified as flagellin by tandem mass spectrometry. Expression of L. monocytogenes flagellin in non-flagellated Escherichia coli conferred on the bacterium the ability to activate TLR5, whereas deletion of the flagellin genes from Salmonella typhimurium abrogated TLR5-stimulating activity. All known TLRs signal through the adaptor protein MyD88. Mice challenged with bacterial flagellin rapidly produced systemic interleukin-6, whereas MyD88-null mice did not respond to flagellin. Our data suggest that TLR5, a member of the evolutionarily conserved Toll-like receptor family, has evolved to permit mammals specifically to detect flagellated bacterial pathogens.

Adaptor Proteins, Signal Transducing↗
PubMed1980

The effect of iron deficiency, protein deficiency and dexamethasone on infection, re-infection and treatment of Giardia muris in the mouse.

The association between nutrient deficiencies, steroid administration, anti-flagellate therapy and giardiasis was examined using the Giardia muris/mouse model. Administration of steroids to BALB/c mice resulted in persisting high levels of infection with G. muris, whereas untreated animals were able to eliminate this parasite. In addition, steroid treatment significantly reduced the efficacy of anti-flagellate therapy. Protein-deficient mice eliminated the parasite at the same rate as mice on an optimum diet and also developed strong acquired resistance to re-infection. A similar pattern was observed in iron-deficient mice, except that the number of parasites that became established during the first 2 weeks of infection was significantly reduced. Thus, there was no evidence of synergism between iron and protein deficiency and infection in this model.

Animals↗
PubMed1996

Isolation and characterization of insertional mutations in flagellin genes in the archaeon Methanococcus voltae.

Methanococcus voltae is a flagellated member of the Domain Archaea that has four flagellin genes arranged in two transcriptional units. One transcriptional unit encodes only flaA while the second is a multi-cistronic unit encoding three flagellin genes (flaB1, flaB2, and flaB3) as well as at least seven other open reading frames downstream. The polymerase chain reaction was used to amplify an internal fragment of the flaA gene which was subsequently cloned into an insertion vector developed for M. voltae. Transformation of protoplasts with this vector led to the isolation of mutant strains that had insertions in flaA or flaB2. Mutant strains carrying insertions in flaA had flagelia that were similar to wild-type cells in both number and appearance when viewed using the electron microscope. In addition, some of these mutant strains had profiles identical to the wild type in immunoblots developed with antisera raised against the 31 kDa flagellin of M. voltae. All flaA mutant strains and the wild-type cells showed immuno-cross-reactive bands at 33 and 31 kDa (corresponding to purified flagellins) as well as at 18 kDa. Some flaA mutant strains also showed an immuno-cross-reactive band at 27 kDa which probably represents a truncated flagellin produced by the insertion vector. However, both types of flaA mutant strains were less motile than the wild type in semi-swarm plate experiments. The mutant strain with an insertion in flaB2 was non-flagellated when examined by electron microscopy and it was non-motile in semi-swarm plate experiments. It represents the first structural mutant strain isolated in a methanogen. This mutant strain lacked the 33, 31, and 18 kDa immuno-cross-reactive bands observed in the wild type and flaA mutant strains, and instead had a novel band at 20 kDa. This band may represent an unmodified flagellin which still has an attached leader peptide. If so, then one of the downstream genes in the multi-cistronic transcriptional unit may encode a leader peptidase for the flagellin system.

Archaeal Proteins↗
PubMed2002

Mutants in flaI and flaJ of the archaeon Methanococcus voltae are deficient in flagellum assembly.

The fla gene locus of Methanococcus voltae encodes the major structural components of the flagellum as well as other flagellar-related proteins. The flaHIJ genes have been found in all flagellated archaea, suggesting a central role in flagella biogenesis. FlaI shares similarity with the type II and type IV secretion NTPases (such as PilB, VirB11 and TadA), and FlaJ exhibits similarity to putative bacterial integral membrane proteins involved in type IV pilus biogenesis such as TadB. In this study, reverse transcription polymerase chain reaction (RT-PCR) and Northern blotting data revealed that flaHIJ are co-transcribed with the upstream structural flagellin genes, thus demonstrating the expression of the entire fla gene cluster in vivo. Non-polar mutants in flaI and flaJ of M. voltae were isolated using insertional inactivation via a novel mutagenic vector. These mutants were non-motile and non-flagellated by microscopy, demonstrating the involvement of FlaI and FlaJ in flagella biogenesis. Interestingly, all the mutants maintained the ability to produce and localize flagellins to the cytoplasmic membrane. Amino-terminal sequencing of flagellins produced by the flaJ mutant strain revealed that the flagellins did not have their cognate leader peptides, thus indicating that preflagellin processing had occurred in vivo. This result was confirmed using an in vitro processing assay. The fla- phenotype and protein secretion characteristics of the flaI and flaJ mutants therefore implicate these respective genes in archaeal flagellin secretion and assembly. These findings further support a model describing the archaeal flagellum as a novel prokaryotic motility structure.

Archaeal Proteins↗
PubMed2003

A lytic transglycosylase homologue, PleA, is required for the assembly of pili and the flagellum at the Caulobacter crescentus cell pole.

Two distinct protein complexes, the flagellum and the pilus biogenesis machinery, are asymmetrically assembled at one pole of the Caulobacter predivisional cell. Cell division yields dissimilar daughter cells: a stalked cell and a swarmer cell that assembles several pili at the flagellated cell pole. Strains bearing mutations in the pleA gene are pililess and non-flagellated. The PleA protein contains a region that is similar to a peptidoglycan-hydrolytic active site, and a point mutation at this site in PleA results in the loss of flagellum and pili biogenesis. PleA was found to be required for the insertion of the outer membrane pilus secretion channel at the cell pole and for the accumulation of the PilA pilin subunit. PleA is also required for the assembly of substructures of the flagellar basal body hook complex that are located in or traverse the peptidoglycan layer. These results argue that PleA facilitates the assembly of envelope-spanning structures at the cell pole. In support of this, PleA was found to be present only during a short interval in the cell cycle that coincides with the assembly of the flagellum and the pilus secretion apparatus.

Amino Acid Sequence↗
PubMed2003

Pseudaminic acid, the major modification on Campylobacter flagellin, is synthesized via the Cj1293 gene.

Flagellins from Campylobacter jejuni 81-176 and Campylobacter coli VC167 are heavily glycosylated. The major modifications on both flagellins are pseudaminic acid (Pse5Ac7Ac), a nine carbon sugar that is similar to sialic acid, and an acetamidino-substituted analogue of pseudaminic acid (PseAm). Previous data have indicated that PseAm is synthesized via Pse5Ac7Ac in C. jejuni 81-176, but that the two sugars are synthesized using independent pathways in C. coli VC167. The Cj1293 gene of C. jejuni encodes a putative UDP-GlcNAc C6-dehydratase/C4-reductase that is similar to a protein required for glycosylation of Caulobacter crescentus flagellin. The Cj1293 gene is expressed either under the control of a sigma 54 promoter that overlaps the coding region of Cj1292 or as a polycistronic message under the control of a sigma 70 promoter upstream of Cj1292. A mutant in gene Cj1293 in C. jejuni 81-176 was non-motile and non-flagellated and accumulated unglycosylated flagellin intracellularly. This mutant was complemented in trans with the homologous C. jejuni gene, as well as the Helicobacter pylori homologue, HP0840, which has been shown to encode a protein with UDP-GlcNAc C6-dehydratase/C4-reductase activity. Mutation of Cj1293 in C. coli VC167 resulted in a fully motile strain that synthesized a flagella filament composed of flagellin in which Pse5Ac7Ac was replaced by PseAm. The filament from the C. coli Cj1293 mutant displayed increased solubility in SDS compared with the wild-type filament. A double mutant in C. coli VC167, defective in both Cj1293 and ptmD, encoding part of the independent PseAm pathway, was also non-motile and non-flagellated and accumulated unglycosylated flagellin intracellularly. Collectively, the data indicate that Cj1293 is essential for Pse5Ac7Ac biosynthesis from UDP-GlcNAc, and that glycosylation is required for flagella biogenesis in campylobacters.

Campylobacter coli↗
PubMed2006

A Vibrio cholerae protease needed for killing of Caenorhabditis elegans has a role in protection from natural predator grazing.

Vibrio cholerae is the causal bacterium of the diarrheal disease cholera, and its growth and survival are thought to be curtailed by bacteriovorous predators, e.g., ciliates and flagellates. We explored Caenorhabditis elegans as a test organism after finding that V. cholerae can cause lethal infection of this nematode. By reverse genetics we identified an extracellular protease, the previously uncharacterized PrtV protein, as being necessary for killing. The killing effect is associated with the colonization of bacteria within the Caenorhabditis elegans intestine. We also show that PrtV is essential for V. cholerae in the bacterial survival from grazing by the flagellate Cafeteria roenbergensis and the ciliate Tetrahymena pyriformis. The PrtV protein appears to have an indirect role in the interaction of V. cholerae with mammalian host cells as judged from tests with tight monolayers of human intestinal epithelial cells. Our results demonstrate a key role for PrtV in V. cholerae interaction with grazing predators, and we establish Caenorhabditis elegans as a convenient organism for identification of V. cholerae factors involved in host interactions and environmental persistence.

Animals↗
PubMed1974

Direct evidence for fluid membranes.

We describe a new kind of cell motility that provides direct, visual evidence for the fluid nature of cell membranes. The movement involves continual, unidirectional rotation of one part of a devescovinid flagellate in relation to a neighboring part, at speeds up to one rotation/1.5 sec (room temperature). Rotation includes the plasma membrane, using the flagellar bases and ectosymbiotic bacteria embedded in pockets of the membrane as visible markers. The plasma membrane between the rotating and stationary surfaces is continuous, without fusions with other membranes, and has the typical trilaminar structure of other cell membranes. The nucleus, helical Golgi complex, and stiff central axostyle also rotate. The head of the flagellate always rotates clockwise (as viewed from the anterior end) in relation to the body, but when the head becomes stuck to debris, the body rotates counterclockwise. Evidence suggests that the microtubular axostyle generates the motive force for rotation.

Animals↗
PubMed1995

A flagellar calmodulin gene of Naegleria, coexpressed during differentiation with flagellar tubulin genes, shares DNA, RNA, and encoded protein sequence elements.

Two calmodulins are synthesized during differentiation of Naegleria gruberi from amoebae to flagellates; one remains in the cell body and the other becomes localized in the flagella. The single, intronless, expressed gene for flagellar calmodulin has been cloned and sequenced. The encoded protein is a typical calmodulin with four putative calcium-binding domains, but it has an amino-terminal extension of 10 divergent amino acids preceding conserved calmodulin residue 4. The transcripts encoding flagellar calmodulin and flagellate cell body calmodulin are clearly divergent. Expression of the flagellar calmodulin gene is differentiation-specific; its mRNA appears and then disappears concurrently with those encoding flagellar alpha- and beta-tubulin. Three provocative sequence elements are shared among these unrelated coexpressed genes: (i) a palindromic DNA sequence element is found in duplicate or triplicate upstream to each transcribed region; (ii) a perfect 12-nucleotide match is found near the AUG start codon of flagellar calmodulin and alpha-tubulin; and (iii) the novel amino-terminal extension of flagellar calmodulin contains a 5-amino-acid element similar to the amino terminus of flagellar alpha-tubulin. These shared sequence elements are proposed to have roles in differentiation, possibly in regulation of transcription, mRNA stability, and localization of these proteins to flagella.

Amino Acid Sequence↗
PubMed2005

Intracellular positioning of isoforms explains an unusually large adenylate kinase gene family in the parasite Trypanosoma brucei.

Adenylate kinases occur classically as cytoplasmic and mitochondrial enzymes, but the expression of seven adenylate kinases in the flagellated protozoan parasite Trypanosoma brucei (order, Kinetoplastida; family, Trypanosomatidae) easily exceeds the number of isoforms previously observed within a single cell and raises questions as to their location and function. We show that a requirement to target adenylate kinase into glycosomes, which are unique kinetoplastid-specific microbodies of the peroxisome class in which many reactions of carbohydrate metabolism are compartmentalized, and two different flagellar structures as well as cytoplasm and mitochondrion explains the expansion of this gene family in trypanosomes. The three isoforms that are selectively built into either the flagellar axoneme or the extra-axonemal paraflagellar rod, which is essential for motility, all contain long N-terminal extensions. Biochemical analysis of the only short form trypanosome adenylate kinase revealed that this enzyme catalyzes phosphotransfer of gamma-phosphate from ATP to AMP, CMP, and UMP acceptors; its high activity and specificity toward CMP is likely to reflect an adaptation to very low intracellular cytidine nucleotide pools. Analysis of some of the phosphotransfer network using RNA interference suggests considerable complexity within the homeostasis of cellular energetics. The anchoring of specific adenylate kinases within two distinct flagellar structures provides a paradigm for metabolic organization and efficiency in other flagellates.

Adenylate Kinase↗
PubMed2000

Estimating the growth potential of the soil protozoan community.

We have developed a method for determining the potential abundance of free-living protozoa in soil. The method permits enumeration of four major functional groups (flagellates, naked amoebae, testate amoebae, and ciliates) and it overcomes some limitations and problems of the usual 'direct' and 'most probable number' methods. Potential abundance is determined using light microscopy, at specific time intervals, after quantitative re-wetting of air-dried soil with rain water. No exogenous carbon substrates or mineral nutrients are employed, so the protozoan community that develops is a function of the resources and inhibitors present in the original field sample. The method was applied to 100 soil samples (25 plots x 4 seasons) from an upland grassland (Sourhope, Southern Scotland) in the UK. Median abundances for all four functional groups lie close to those derived from the literature on protozoa living in diverse soil types. Flagellates are the most abundant group in soil, followed by the naked amoebae, then the testate amoebae and ciliates. This order is inversely related to typical organism size in each group. Moreover, preliminary evidence indicates that each functional group contains roughly the same number of species. All of these observations would be consistent with soil having fractal structure across the size-scale perceived by protozoa. The method described will be useful for comparing the effects on the soil protozoan community of different soil treatments (e.g. liming and biocides).

Animals↗
PubMed2001

Involvement of a 40-kDa glycoprotein in food recognition, prey capture, and induction of phagocytosis in the protozoon Actinophrys sol.

A 40-kDa glycoprotein (gp40) was identified as a Con A-binding adhesive substance of the heliozoon Actinophrys sol for immobilizing and ingesting prey flagellates. Isolation and partial characterization of gp40 showed that: 1) gp40 is a major Con A-binding protein of Actinophrys with a molecular weight of 40 kDa, and is stored in secretory granules called extrusomes; 2) gp40 was purified by Con A-affinity chromatography, and the N-terminal amino acid sequence was determined as H2N-KVLK-FEDDFDTFDLQ; 3) prey flagellates became adhered to gp40-immobilized agarose beads; 4) phagocytosis of Actinophrys was induced against gp40-immobilized agarose beads; and 5) solubilized gp40 induced exocytosis of extrusomes and cell fusion of heliozoons. These results indicate that gp40 is a multi-functional secretory protein of Actinophrys, which is required in correct targeting of the heliozoon to food organisms as well as in self-recognition.

Amino Acid Sequence↗
PubMed2000

Phylogenetic position of Cryothecomonas inferred from nuclear-encoded small subunit ribosomal RNA.

The systematic position of the genus Cryothecomonas has been determined from an analysis of the nuclear-encoded small subunit ribosomal RNA gene of Cryothecomonas longipes and two strains of Cryothecomonas aestivalis. Our phylogenetic trees inferred from maximum likelihood, distance and maximum parsimony methods robustly show that the genus Cryothecomonas clusters within the phylum Cercozoa, and is related to the sarcomonad flagellate Heteromita globosa. Morphological data supporting the taxonomic placement of Cryothecomonas near the sarcomonad flagellates has been compiled from the literature. The high number of nucleotide substitutions found between two morphologically indistinguishable strains of Cryothecomonas aestivalis suggests the possibility of cryptic species within Cryothecomonas aestivalis.

Animals↗
PubMed1991

Comparison of Trypanosoma grayi-like isolates from west and east Africa.

Three flagellates recently isolated from the hindguts of tsetse flies in West Africa were compared with a previously described T. grayi-like trypanosome isolated in East Africa. In media with Microtus agrestis feeder layer cells, the flagellates developed into bloodstream-like trypomastigotes, which resembled the description of T. grayi from the blood of crocodiles. The results of isoenzyme electrophoresis suggest that the isolates are T. grayi-like trypanosomes, and that some variation exists between the West and East African stocks of these reptile trypanosomes.

Africa, Western↗
PubMed1994

Phlebotomine sandflies associated with households of human visceral leishmaniasis cases in Baringo District, Kenya.

A 12-month field study on sandflies was conducted from April 1992 to March 1993 at three locations in Baringo District, Rift Valley Province, Kenya. Study sites were selected based on their close proximity to the households of three patients who had had parasitologically confirmed visceral leishmaniasis in 1988, 1990 or 1991. Sandfly populations were highest during the two rainy seasons, April-June and November-December. A significant association was detected between the monthly abundance of sandflies and rainfall in the previous month. A significantly higher proportion of females than males was collected in light traps than on sticky paper traps set in termite mounds or animal burrows: approximately twice as many males as females were collected from the sticky paper traps whereas twice as many females as males were collected in light traps. Over 10% of the female sandflies collected from animal burrows and termite mounds were gravid, indicating that these flies were seeking oviposition sites at these locations. A total of 2231 sandflies was collected and five females were found to have flagellates in their midguts. The flagellates cultured from four Sergentomyia spp. were tentatively identified as Crithidia sp. by cellulose acetate electrophoresis (CAE). The promastigotes from the one Phlebotomus martini female found with an infected midgut were identified as Leishmania donovani by CAE.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Insidious effects of a toxic estuarine dinoflagellate on fish survival and human health.

The estuarine dinoflagellate Pfiesteria piscicida gen. et sp. nov. produces exotoxin(s) that can be absorbed from water or fine aerosols. Culture filtrate (0.22 microns porosity filters, > 250 toxic flagellated cells/ml) induces formation of open ulcerative sores, hemorrhaging, and death of finfish and shellfish. Human exposure to aerosols from ichthyotoxic cultures (> or = 2000 cells/ml) has been associated with narcosis, respiratory distress with asthma-like symptoms, severe stomach cramping, nausea, vomiting, and eye irritation with reddening and blurred vision (hours to days); autonomic nervous system dysfunction [localized sweating, erratic heart beat (weeks)]; central nervous system dysfunction [sudden rages and personality change (hours to days), and reversible cognitive impairment and short-term memory loss (weeks)]; and chronic effects including asthma-like symptoms, exercise fatigue, and sensory symptoms (tingling or numbness in lips, hands, and feet; months to years). Elevated hepatic enzyme levels and high phosphorus excretion in one human exposure suggested hepatic and renal dysfunction (weeks); easy infection and low counts of several T-cell types may indicate immune system suppression (months to years). Pfiesteria piscicida is euryhaline and eurythermal, and in bioassays a nontoxic flagellated stage has increased under P enrichment (> or = 100 micrograms SRP/L), suggesting a stimulatory role of nutrients. Pfiesteria-like dinoflagellates have been tracked to fish kill sites in eutrophic estuaries from Delaware Bay through the Gulf Coast. Our data point to a critical need to characterize their chronic effects on human health as well as fish recruitment, disease resistance, and survival.

Adult↗
PubMed1987

Basal body reorientation mediated by a Ca2+-modulated contractile protein.

A rapid, Ca2+-dependent change in the angle between basal bodies (up to 180 degrees) is associated with light-induced reversal of swimming direction (the "photophobic" response) in a number of flagellated green algae. In isolated, detergent-extracted, reactivated flagellar apparatus complexes of Spermatozopsis similis, axonemal beat form conversion to the symmetrical/undulating flagellar pattern and basal body reorientation (from the antiparallel to the parallel configuration) are simultaneously induced at greater than or equal to 10(-7) M Ca2+. Basal body reorientation, however, is independent of flagellar beating since it is induced at greater than or equal to 10(-7) M Ca2+ when flagellar beating is inhibited (i.e., in the presence of 1 microM orthovanadate in reactivation solutions; in the absence of ATP or dithiothreitol in isolation and reactivation solutions), or when axonemes are mechanically removed from flagellar apparatuses. Although frequent axonemal beat form reversals were induced by varying the Ca2+ concentration, antiparallel basal body configuration could not be restored in isolated flagellar apparatuses. Observations of the photophobic response in vivo indicate that even though the flagella resume the asymmetric, breaststroke beat form 1-2 s after photostimulation, antiparallel basal body configuration is not restored until a few minutes later. Using an antibody generated against the 20-kD Ca2+-modulated contractile protein of striated flagellar roots of Tetraselmis striata (Salisbury, J. L., A. Baron, B. Surek, and M. Melkonian, 1984, J. Cell Biol., 99:962-970), we have found the distal connecting fiber of Spermatozopsis similis to be immunoreactive by indirect immunofluorescence and immunogold electron microscopy. Electrophoretic and immunoblot analysis indicates that the antigen of S. similis flagellar apparatuses consists, like the Tetraselmis protein, of two acidic isoforms of 20 kD. We conclude that the distal basal body connecting fiber is a contractile organelle and reorients basal bodies during the photophobic response in certain flagellated green algae.

Calcium↗
PubMed1993

SF-assemblin, the structural protein of the 2-nm filaments from striated microtubule associated fibers of algal flagellar roots, forms a segmented coiled coil.

The microtubule associated system I fibers of the basal apparatus of the flagellate green alga Spermatozopsis similis are noncontractile and display a 28-nm periodicity. Paracrystals with similar periodicities are formed in vitro by SF-assemblin, which is the major protein component of system I fibers. We have determined the amino acid sequence of SF-assemblin and show that it contains two structural domains. The NH2-terminal 31 residues form a nonhelical domain rich in proline. The rod domain of 253 residues is alpha-helical and seems to form a segmented coiled coil with a 29-residue repeat pattern based on four heptads followed by a skip residue. The distinct cluster of acidic residues at the COOH-terminal end of the motifs (periodicity about 4 nm) may be related to tubulin binding of SF-assemblin and/or its self assembly. A similar structure has been predicted from cDNA cloning of beta-giardin, a protein of the complex microtubular apparatus of the sucking disc in the protozoan flagellate Giardia lamblia. Although the rod domains of SF-assemblin and beta-giardin share only 20% sequence identity, they have exactly the same length and display 42% sequence similarity. These results predict that system I fibers and related microtubule associated structures arise from molecules able to form a special segmented coiled coil which can pack into 2-nm filaments. Such molecules seem subject to a strong evolutionary drift in sequence but not in sequence principles and length. This conservation of molecular architecture may have important implications for microtubule binding.

Amino Acid Sequence↗