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101.
Global Regulator MorA Affects Virulence-Associated Protease Secretion in Pseudomonas aeruginosa PAO1
Ayshwarya Ravichandran Malarmathy Ramachandran Tanujaa Suriyanarayanan Chui Ching Wong Sanjay Swarup 《PloS one》2015,10(4)
Bacterial invasion plays a critical role in the establishment of Pseudomonas aeruginosa infection and is aided by two major virulence factors – surface appendages and secreted proteases. The second messenger cyclic diguanylate (c-di-GMP) is known to affect bacterial attachment to surfaces, biofilm formation and related virulence phenomena. Here we report that MorA, a global regulator with GGDEF and EAL domains that was previously reported to affect virulence factors, negatively regulates protease secretion via the type II secretion system (T2SS) in P. aeruginosa PAO1. Infection assays with mutant strains carrying gene deletion and domain mutants show that host cell invasion is dependent on the active domain function of MorA. Further investigations suggest that the MorA-mediated c-di-GMP signaling affects protease secretion largely at a post-translational level. We thus report c-di-GMP second messenger system as a novel regulator of T2SS function in P. aeruginosa. Given that T2SS is a central and constitutive pump, and the secreted proteases are involved in interactions with the microbial surroundings, our data broadens the significance of c-di-GMP signaling in P. aeruginosa pathogenesis and ecological fitness. 相似文献
102.
Unusual fungal agents that exist environmentally as saprophytes can often lead to opportunistic infections. Hyalohyphomycosis
is a group of fungal infections caused by fungi characterized by hyaline septate hyphae and can infect both immunocompetent
as well as immunocompromised patients. Many a times it becomes difficult to distinguish a pathogenic and a contaminant fungus,
because many such agents can assume clinical significance depending on circumstances. Subcutaneous and invasive fungal infection
due to the emerging hyalohyphomycotic fungus, Acremonium, has drawn the attention of clinicians and microbiologists, as a potential pathogen in patients with and without underlying
risk factors. Generally considered to be minimally invasive in the past, genus Acremonium has been responsible for eumycotic mycetomas and focal infections in otherwise healthy individuals. It has also been increasingly
implicated in systemic fungal diseases. The management with different antifungals in various clinical situations has been
very conflicting and hence needs to be carefully evaluated. This overview is an endeavor to consolidate the available clinical
infections due to Acremonium and the recommendations on treatment. 相似文献
103.
Dev Chandran Kolli Bhaktavatsala Reddy Shahana Pallichera Vijayan Parthasarthy Sugumar Gudavalli Sudha Rani Ponsekaran Santha Kumar Lingala Rajendra Villuppanoor Alwar Srinivasan 《Indian journal of microbiology》2010,50(3):266-274
Peste des Petits Ruminants (PPR) is a highly contagious animal disease caused by the Peste des Petits Ruminants virus (PPRV) belonging to the genus morbillivirus and family Paramyxoviridae. The disease results in high morbidity and mortality
in goats, sheep and in some small wild ruminants. The presence of large number of small ruminants reared in endemic areas
makes PPR a notorious disease threatening the livelihood of poor farmers. Conventional vaccination using a live, attenuated
vaccine gives adequate protection but cannot be used in case of eradication of the disease due to difficulty in differentiation
of infected animals from the vaccinated ones. 相似文献
104.
R. K. Sharma M. S. Negi S. Sharma P. Bhardwaj R. Kumar E. Bhattachrya S. B. Tripathi D. Vijayan A. R. Baruah S. C. Das B. Bera R. Rajkumar J. Thomas R. K. Sud N. Muraleedharan M. Hazarika M. Lakshmikumaran S. N. Raina P. S. Ahuja 《Biochemical genetics》2010,48(7-8):549-564
India has a large repository of important tea accessions and, therefore, plays a major role in improving production and quality of tea across the world. Using seven AFLP primer combinations, we analyzed 123 commercially important tea accessions representing major populations in India. The overall genetic similarity recorded was 51%. No significant differences were recorded in average genetic similarity among tea populations cultivated in various geographic regions (northwest 0.60, northeast and south both 0.59). UPGMA cluster analysis grouped the tea accessions according to geographic locations, with a bias toward China or Assam/Cambod types. Cluster analysis results were congruent with principal component analysis. Further, analysis of molecular variance detected a high level of genetic variation (85%) within and limited genetic variation (15%) among the populations, suggesting their origin from a similar genetic pool. 相似文献
105.
Ajay Kumar D.M. Pandey Thomson Abraham Jacob Mathew Padma Ramachandran 《Archives Of Phytopathology And Plant Protection》2013,46(6):710-720
Tapping panel dryness (TPD) syndrome affecting rubber tree (Hevea brasiliensis) is known to reduce natural latex production. Its aetiology remains ambiguous despite long years of research. A low molecular weight RNA similar to viroid RNA was isolated from TPD-affected samples of rubber trees. In the present study, a modified return-polyacrylamide gel electrophoresis procedure was standardised. The viroid-like low molecular weight (LMW) RNA was found associated with leaf, bark and root tissues and rubber seedlings. The technique was employed to detect LMW RNA in different clones of rubber planted in different locations and in bud-grafted plants. The LMW RNA isolated from TPD-affected trees was found infectious on seedlings of tomato cv Pusa Ruby. The LMW RNA was reisolated from symptomatic tomato leaves but not from control plants. This is for the first time that a biotic agent, a viroid RNA, is found consistently associated with the syndrome. The technology developed can be useful to demonstrate the onset of TPD in untapped trees in the absence of other methods such as nucleic acid hybridisation. 相似文献
106.
Cytotoxic activity of nucleoside diphosphate kinase secreted from Mycobacterium tuberculosis. 总被引:2,自引:0,他引:2
Puneet Chopra Anubha Singh Anil Koul S Ramachandran Karl Drlica Anil K Tyagi Yogendra Singh 《European journal of biochemistry》2003,270(4):625-634
Pathogenicity of Mycobacterium tuberculosis is closely related to its ability to survive and replicate in the hostile environment of macrophages. For some pathogenic bacteria, secretion of ATP-utilizing enzymes into the extracellular environment aids in pathogen survival via P2Z receptor-mediated, ATP-induced death of infected macrophages. A component of these enzymes is nucleoside diphosphate kinase (Ndk). The ndk gene was cloned from M. tuberculosis H37Rv and expressed in Escherichia coli. Ndk was secreted into the culture medium by M. tuberculosis, as determined by enzymatic activity and Western blotting. Purified Ndk enhanced ATP-induced macrophage cell death, as assayed by the release of [14C]adenine. A catalytic mutant of Ndk failed to enhance ATP-induced macrophage cell death, and periodate-oxidized ATP (oATP), an irreversible inhibitor of P2Z receptor, blocked ATP/Ndk-induced cell death. Purified Ndk was also found to be autophosphorylated with broad specificity for all nucleotides. Conversion of His117-->Gln, which is part of the nucleotide-binding site, abolished autophosphorylation. Purified Ndk also showed GTPase activity. Collectively, these results indicate that secreted Ndk of M. tuberculosis acts as a cytotoxic factor for macrophages, which may help in dissemination of the bacilli and evasion of the immune system. 相似文献
107.
A. M. Choudhury K. Y. Chu G. W. Kenner S. Moore K. L. Ramachandran R. Ramage 《Bioorganic chemistry》1979,8(4):471-483
The synthesis of fragments corresponding to the N-terminal region of porcine big gastrin is described. Radioimmunoassay using synthetic peptides supports the revised structure for the hormone. 相似文献
108.
Summary Crypts of the lingual tonsil were investigated in 10 male and female Macaca fascicularis by use of correlated light and scanning-electron microscopy. Counting of crypt openings provided an estimate of the total number of respective crypto-lymphatic units, which were found to range from 20 to 39. Crypt openings appeared in three distinct morphological varieties, i.e. circular, oval or slit-like. Tonsillar units existed individually or were arranged in a rosary fashion below a slit-like mucosal fold serving as a common exit. Although the crypt epithelium was generally non-keratinized, individual cells showing a surface pattern similar to that of the keratinized cells could be encountered. The crypt epithelium was frequently fragmented and showed heavy mononuclear cell infiltration and surface discontinuities, with lymphoid cells coming in contact with luminal contents. The crypt lumen either appeared as a simple epithelial invagination or existed as a complex, cavernous pouch with many blind-ending diverticula. The lumen contained a mixture of exfoliated epithelial cells, leucocytes and bacteria. The secretory ducts of the posterior lingual glands opened occasionally at various levels into the crypt lumina or independently to the exterior. 相似文献
109.
Amino acid sequence of retinal transducin at the site ADP-ribosylated by cholera toxin 总被引:31,自引:0,他引:31
C Van Dop M Tsubokawa H R Bourne J Ramachandran 《The Journal of biological chemistry》1984,259(2):696-698
Transducin was [32P]ADP-ribosylated by cholera toxin in bovine retinal rod outer segments and then partially purified on omega-amino octyl agarose to remove other ADP-ribosylated proteins. Trypsin digestion of the ADP-ribosylated transducin and further purification using boronate-polyacrylamide beads and high performance liquid chromatography yielded a single radiolabeled tetrapeptide, Ser-Arg-Val-Lys. The ADP-ribose is linked to the guanidinium group of arginine. 相似文献
110.
Buoyant density gradient analysis of nuclear DNA of fourCucumis species showed asymmetric profiles indicating the presence of satellite DNA sequences in the nuclear genome. A highly repeated satellite DNA sequence was isolated from the nuclear genome ofC. metuliferus under neutral CsCl gradients. The satellite DNA constitutes about 4.96% of total nuclear DNA and has 48.06% guanine plus cytosine content. The kinetic complexity of satellite DNA is 150 times smaller than T4 phage DNA and the base sequence divergence is low.3H-labeled cRNA transcribed from satellite DNA hybridized clearly to six heterochromatic knobs of pachytene chromosomes. The knob heterochromatin can be distinguished by Giemsa C-banding of pachytene chromosomes. Restriction enzyme analysis and Southern blot hybridization indicated that the satellite DNA has a tandem arrangement and predominantly formed two bands of size 210 and 151 base pairs. Absence of knob satellite DNA ofC. metuliferus in the nuclear genomes ofC. melo, C. anguria andC. sativus showed thatC. metuliferus remains isolated within the genusCucumis. 相似文献