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1.
Twitching motility allows Pseudomonas aeruginosa to respond to stimuli by extending and retracting its type IV pili (TFP). PilJ is a protein necessary for this surface-associated
twitching motility and bears high sequence identity with Escherichia coli methyl-accepting chemotaxis proteins (MCP). Here, we report that whereas wild-type P. aeruginosa PAO1 cells have extended pili at a single pole, pilJ mutant cells have shortened pili often at both poles despite normal levels of pilin accumulation, suggesting that PilJ is
required for full TFP assembly/extension. Using yellow fluorescent protein fusions (pilJ-yfp), both plasmid born and in-frame chromosomal constructs, we determined that PilJ localizes to both poles of the cell. Overexpression
of pilJ-yfp resulted in the protein accumulating between the poles.
Paul DeLange and Tracy Collins contributed equally to this work. 相似文献
2.
M. Victoria Delpino Diego J. Comerci Mary Ann Wagner Michel Eschenbrenner Cesar V. Mujer Rodolfo A. Ugalde Carlos A. Fossati Pablo C. Baldi Vito G. DelVecchio 《Archives of microbiology》2009,191(7):571-581
The virB genes coding type IV secretion system are necessary for the intracellular survival and replication of Brucella spp. In this study, extracellular proteins from B. abortus 2308 (wild type, WT) and its isogenic virB10 polar mutant were compared. Culture supernatants harvested in the early stationary phase were concentrated and subjected
to 2D electrophoresis. Spots present in the WT strain but absent in the virB10 mutant (differential spots) were considered extracellular proteins released in a virB-related manner, and were identified by MALDI-TOF analysis and matching with Brucella genomes. Among the 11 differential proteins identified, DnaK chaperone (Hsp70), choloylglycine hydrolase (CGH) and a peptidyl-prolyl
cis–trans isomerase (PPIase) were chosen for further investigation because of their homology with extracellular and/or virulence
factors from other bacteria. The three proteins were obtained in recombinant form and specific monoclonal antibodies (mAbs)
were prepared. By Western blot with these mAbs, the three proteins were detected in supernatants from the WT but not in those
from the virB10 polar mutant or from strains carrying non-polar mutations in virB10 or virB11 genes. These results suggest that the expression of virB genes affects the extracellular release of DnaK, PPIase and CGH, and possibly other proteins from B. abortus. 相似文献
3.
Karseno Kazuo Harada Takeshi Bamba Susilaningsih Dwi Aparat Mahakhant Tomoaki Yoshikawa Kazumasa Hirata 《Biotechnology letters》2009,31(7):999-1003
During growth of the freshwater cyanobacteria, Oscillatoria sp. BTCC/A0004, and Scytonema sp. TISTR 8208, a pink pigment is released into the growth medium. The pigment from each source had a molecular weight of
approximately 250 kDa and had adsorption maxima at 560 and 620 nm. These results suggest that pink pigment is a phycoerythrin-like
protein. It inhibited the growth of green algae, Chlorella fusca and Chlamydomonas reinhardtii, but not other cyanobacteria or true bacteria. The concentration at which growth inhibition 50% occurred was 0.5, 6 and more
than 10 mg ml−1, respectively. 相似文献
4.
The foodborne pathogen Bacillus cereus can form biofilms on various food contact surfaces, leading to contamination of food products. To study the mechanisms of
biofilm formation by B. cereus, a Tn5401 library was generated from strain UW101C. Eight thousand mutants were screened in EPS, a low nutrient medium. One mutant
(M124), with a disruption in codY, developed fourfold less biofilm than the wild-type, and its defective biofilm phenotype was rescued by complementation.
Addition of 0.1% casamino acids to EPS prolonged the duration of biofilms in the wild-type but not codY mutant. When decoyinine, a GTP synthesis inhibitor, was added to EPS, biofilm formation was decreased in the wild-type but
not the mutant. The codY mutant produced three times higher protease activity than the wild-type. Zymogram and SDS-PAGE data showed that production
of the protease (∼130 kDa) was repressed by CodY. Addition of proteinase K to EPS decreased biofilm formation by the wild-type.
Using a dpp-lacZ fusion reporter system, it was shown that that the B. cereus CodY can sense amino acids and GTP levels. These data suggest that by responding to amino acids and intracellular GTP levels
CodY represses production of an unknown protease and is involved in biofilm formation. 相似文献
5.
Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes. 相似文献
6.
Telomeric DNA-binding proteins (TBPs) are crucial components that regulate the structure and function of eukaryotic telomeres and are evolutionarily conserved. We have identified two homologues of AtTBP1 (for Arabidopsis thaliana telomeric DNA binding protein 1), designated as AtTBP2 and AtTRP2, which encode proteins that specifically bind to the telomeric DNA of this plant. These proteins show extensive homology with other known plant TBPs. The isolated C-terminal segments of these proteins were capable of sequence-specific binding to duplex telomeric plant DNA in vitro. DNA bending assays using the Arabidopsis TBPs revealed that AtTBP1 and AtTBP2 have DNA-bending abilities comparable to that of the human homologue hTRF1, and higher than those of AtTRP1 and AtTRP2. 相似文献
7.
The relationship between Sporidiobolus johnsonii and S. salmonicolor was investigated using rDNA sequence data. Two statistically well-supported clades were obtained. One clade included the
type strain of S. johnsonii and the other included the type strain of S. salmonicolor. However, some mating strains of S. salmonicolor were found in the S. johnsonii group. These strains belonged to mating type A2 and were sexually compatible with mating type A1 strains from the S. salmonicolor group. DNA–DNA reassociation values were high within each clade and moderate between the two clades. In the re-investigation
of teliospore germination, we observed that the basidia of S. salmonicolor were two-celled. In S. johnsonii, basidia were not formed and teliospore germination resulted in direct formation of yeast cells. We hypothesize that the
S. johnsonii clade is becoming genetically isolated from the S. salmonicolor group and that a speciation process is presently going on. We suspect that the observed sexual compatibility between strains
of the S. johnsonii and S. salmonicolor groups and the possible genetic flow between the two species has little biological relevance because distinct phenotypes
have been fixed in the two taxa and intermediate (hybrid) sequences for LSU and ITS rDNAs have not been detected.
An erratum to this article can be found at 相似文献
8.
Recently it was shown that Pyrococcus furiosus uses its flagella not only for swimming, but also for establishment of cell-cell connections, and for adhesion to abiotic surfaces. Therefore, it was asked here if P. furiosus might be able to adhere also to biotic surfaces. Since Methanopyrus kandleri can be found in habitats similar to those of P. furiosus (seawater close to the boiling point and anaerobic conditions) it was tested if interactions between both archaea occur. Using a standard medium and a gas phase reduced in H(2) (compared with the optimal gas phase for M. kandleri) we were able to grow both species in a stable coculture. Very interestingly, M. kandleri could adhere to glass under such conditions, but not P. furiosus. This latter archaeum, however, was able to adhere onto M. kandleri cells and onto itself, resulting in structured biofilms on glass. These very often appeared as a bottom layer of M. kandleri cells covered by a multitude of P. furiosus cells. Interactions between P. furiosus and M. kandleri were mediated not only by flagella, but also by direct cell-cell contact. 相似文献
9.
Ipsita Sahu B. K. Das Nilima Marhual M. Samanta B. K. Mishra A. E. Eknath 《Indian journal of microbiology》2011,51(4):515-520
In the present study the haemolytic and proteolytic activity of extracellular products (ECP) secreted from Aeromonas hydrophila (CAHH14 strain) were studied with respect to temperature and different time of incubation as well as its lethal toxicity
on rohu, Labeo rohita. The strain was isolated from Catla catla (showing abdominal dropsy symptom) collected from the pond of Central Institute of Freshwater Aquaculture (CIFA), Bhubaneswar,
India and was characterized on the basis of biochemical tests. The highest production of haemolysin was achieved when the
bacteria was grown at 35°C for 30 h. The proteolytic activity was found to be highest when the bacterium was grown at 30°C
for 36 h. The haemolytic and proteolytic toxin produced by Aeromonas hydrophila was found to be lethal to rohu (LD50 1.7 × 104 cfu/ml). The lethality of ECP was decreased by heating and completely inactivated by boiling at 100°C for 10 min. This indicates
that protease activity and haemolytic activity of A. hydrophila ECP was temperature dependant. 相似文献
10.
11.
Irene C Maciariello C Micheli G Theis JF Newlon CS Fabiani L 《Molecular genetics and genomics : MGG》2007,277(3):287-299
Eukaryotic chromosomal DNA replication is initiated by a highly conserved set of proteins that interact with cis-acting elements on chromosomes called replicators. Despite the conservation of replication initiation proteins, replicator
sequences show little similarity from species to species in the small number of organisms that have been examined. Examination
of replicators in other species is likely to reveal common features of replicators. We have examined a Kluyeromyces lactis replicator, KARS12, that functions as origin of DNA replication on plasmids and in the chromosome. It contains a 50-bp region with similarity
to two other K. lactis replicators, KARS101 and the pKD1 replication origin. Replacement of the 50-bp sequence with an EcoRI site completely abrogated the ability of KARS12 to support plasmid and chromosomal DNA replication origin activity, demonstrating this sequence is a common feature of K. lactis replicators and is essential for function, possibly as the initiator protein binding site. Additional sequences up to 1 kb
in length are required for efficient KARS12 function. Within these sequences are a binding site for a global regulator, Abf1p, and a region of bent DNA, both of which
contribute to the activity of KARS12. These elements may facilitate protein binding, protein/protein interaction and/or nucleosome positioning as has been proposed
for other eukaryotic origins of DNA replication. 相似文献
12.
Studying Pneumocystis has proven to be a challenge from the perspective of propagating a significant amount of the pathogen in a facile manner.
The study of several fungal pathogens has been aided by the use of invertebrate model hosts. Our efforts to infect the invertebrate
larvae Galleria
mellonella with Pneumocystis proved futile since P. murina neither caused disease nor was able to proliferate within G. mellonella. It did, however, show that the pathogen could be rapidly cleared from the host. 相似文献
13.
Noel H. Holmgren 《Brittonia》2018,70(1):115-139
A revision of Penstemon sect. Saccanthera subsect. Serrulati includes a new species (P. salmonensis), a new variety (P. triphyllus var. infernalis), and the elevation of a subspecies to species (P. curtiflorus), bringing the total number of species to eight, which are keyed and described, complete with nomenclature and type citations. 相似文献
14.
Bacterial biofilms are associated with chronic infections due to their resistance to antimicrobial agents. Staphylococcus
aureus is a versatile human pathogen and can form biofilms on human tissues and diverse medical devices. To identify novel biofilm
inhibitors of S. aureus, the supernatants from a library of 458 Actinomycetes strains were screened. The culture supernatants (1% v/v) of more than 10 Actinomycetes strains inhibited S. aureus biofilm formation by more than 80% without affecting the growth. The culture supernatants of these biofilm-reducing Actinomycetes strains contained a protease (equivalent to 0.1 μg proteinase K ml−1), which both inhibited S. aureus biofilm formation and detached pre-existing S. aureus biofilms. This study suggests that protease treatment could be a feasible tool to reduce and eradicate S. aureus biofilms. 相似文献
15.
A genetic transformation system has been developed for callus cells of Crataegus
aronia using Agrobacterium
tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with
5 mg l−1 Indole-3-butyric acid (IBA) and 0.5 mg l−1 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different
types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red
colored callus was obtained on MS medium supplemented with 2 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l−1 kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli
were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l−1 hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this
is the first time to report an Agrobacterium-mediated transformation system in Crataegus
aronia. 相似文献
16.
The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae. 相似文献
17.
Notocactus scopa cv. Soonjung was subjected to in planta Agrobacterium tumefaciens-mediated transformation with vacuum infiltration, pin-pricking, and a combination of the two methods. The pin-pricking combined with vacuum infiltration (20-30 cmHg for 15 min) resulted in a transformation efficiency of 67-100%, and the expression of the uidA and nptII genes was detected in transformed cactus. The established in planta transformation technique generated a transgenic cactus with higher transformation efficiency, shortened selection process, and stable gene expression via asexual reproduction. All of the results showed that the in planta transformation method utilized in the current study provided an efficient and time-saving procedure for the delivery of genes into the cactus genome, and that this technique can be applied to other asexually reproducing succulent plant species. 相似文献
18.
Eun Chan Yang Myung Sook Kim Paul John L. Geraldino Dinabandhu Sahoo Jong-Ahm Shin Sung Min Boo 《Journal of applied phycology》2008,20(2):161-168
The mitochondrial cytochrome c oxidase subunit I gene sequence was recently developed for DNA barcoding of red algal species.
We determined the 1245 base pairs of the gene from 27 taxa of an agar-producing species, Gracilaria vermiculophylla, and putative relatives and compared the results with rbcL data from the same species. A total of 392 positions (31.5%) were variable, 282 positions (22.6%) were parsimoniously informative,
and average sequence divergence was 13% in an ingroup. Within G. vermiculophylla, pairwise divergence of the gene was variable up to 11 bp (0.9%). Seven recognized haplotypes of cox1 tended to be geographically related. In the aligned 1386 bp of rbcL, three haplotypes were recognized. These results suggest that cox1 is a valuable molecular marker within species and will be very useful in haplotype analyses. 相似文献
19.
Sidorenko VS Rot MA Filipenko ML Nevinsky GA Zharkov DO 《Biochemistry. Biokhimii?a》2008,73(4):442-450
Oxidized bases are removed from DNA of Escherichia coli by enzymes formamidopyrimidine DNA glycosylase (Eco-Fpg) and endonuclease VIII (Eco-Nei) of the same structural family Fpg/Nei. New homologs of these enzymes not characterized earlier have been found in genomes of Actinobacteria. We have cloned and expressed two paralogs (Mtu-Nei2 and Mtu-Fpg2) from 36KAZ and KHA94 isolates of Mycobacterium tuberculosis and studied their ability to participate in DNA repair. Under heterologous expression in E. coli, Mtu-Nei2 decreased the rate of spontaneous mutagenesis in the rpoB gene, whereas Mtu-Fpg2 moderately increased it, possibly due to absence of residues crucially important for catalysis in this protein. Mtu-Nei2 was highly active toward double-stranded DNA substrates containing dihydrouracil residues and apurine-apyrimidine sites and was less efficient in cleavage of substrates containing 8-oxoguanine and uracil residues. These lesions, as well as 8-oxoadenine residues, were also recognized and removed by the enzyme from single-stranded DNA. Fpg and Nei homologs from M. tuberculosis can play an important role in protection of bacteria against genotoxic stress caused by oxidative burst in macrophages. 相似文献
20.
To screen stimulators from Chinese medicinal insects for mycelial growth and polysaccharides production of Ganoderma lucidum, G. lucidum was inoculated into the media with and without supplementation of medicinal insect extracts. The ethyl acetate extract of
Eupolyphaga sinensis at 55 mg l−1 lead to significant increase in both biomass and intracellular polysaccharides (IPS) concentration from 8.53 ± 0.41 to 14.16 ± 0.43
and 1.28 ± 0.09 to 2.13 ± 0.11 g l−1, respectively. In addition, the ethyl acetate extract of Catharsius molossus at 55 mg l−1 significantly enhanced extracellular polysaccharides (EPS) production; the EPS yield increased from 350.9 ± 14.1 to 475.1 ± 15.3 mg
l−1. There were no new components in the two types of polysaccharides obtained by the addition of the insect extracts. 相似文献