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991.
Mariana Romo-Castillo Angel Andrade Norma Espinosa Julia Monjarás Feria Eduardo Soto Miguel Díaz-Guerrero Bertha González-Pedrajo 《Journal of bacteriology》2014,196(12):2227-2241
Type III secretion systems (T3SSs) are multiprotein molecular devices used by many Gram-negative bacterial pathogens to translocate effector proteins into eukaryotic cells. A T3SS is also used for protein export in flagellar assembly, which promotes bacterial motility. The two systems are evolutionarily related, possessing highly conserved components in their export apparatuses. Enteropathogenic Escherichia coli (EPEC) employs a T3SS, encoded by genes in the locus of enterocyte effacement (LEE) pathogenicity island, to colonize the human intestine and cause diarrheal disease. In the present work, we investigated the role of the LEE-encoded EscO protein (previously Orf15 or EscA) in T3SS biogenesis. We show that EscO shares similar properties with the flagellar FliJ and the Yersinia YscO protein families. Our findings demonstrate that EscO is essential for secretion of all categories of T3SS substrates. Consistent with its central role in protein secretion, it was found to interact with the ATPase EscN and its negative regulator, EscL, of the export apparatus. Moreover, we show that EscO stimulates EscN enzymatic activity; however, it is unable to upregulate ATP hydrolysis in the presence of EscL. Remarkably, EscO partially restored the swimming defect of a Salmonella flagellar fliJ mutant and was able to stimulate the ATPase activity of FliI. Overall, our data indicate that EscO is the virulence counterpart of the flagellar FliJ protein. 相似文献
992.
Peter Loskill Pedro?M. Pereira Philipp Jung Markus Bischoff Mathias Herrmann Mariana?G. Pinho Karin Jacobs 《Biophysical journal》2014,107(5):1082-1089
We have used atomic-force microscopy (AFM) to probe the effect of peptidoglycan crosslinking reduction on the elasticity of the Staphylococcus aureus cell wall, which is of particular interest as a target for antimicrobial chemotherapy. Penicillin-binding protein 4 (PBP4) is a nonessential transpeptidase, required for the high levels of peptidoglycan crosslinking characteristic of S. aureus. Importantly, this protein is essential for β-lactam resistance in community-acquired, methicillin-resistant S. aureus (MRSA) strains but not in hospital-acquired MRSA strains. Using AFM in a new mode for recording force/distance curves, we observed that the absence of PBP4, and the concomitant reduction of the peptidoglycan crosslinking, resulted in a reduction in stiffness of the S. aureus cell wall. Importantly, the reduction in cell wall stiffness in the absence of PBP4 was observed both in community-acquired and hospital-acquired MRSA strains, indicating that high levels of peptidoglycan crosslinking modulate the overall structure and mechanical properties of the S. aureus cell envelope in both types of clinically relevant strains. Additionally, we were able to show that the applied method enables the separation of cell wall properties and turgor pressure. 相似文献
993.
Mariana P.C. Ribeiro Isabel Nunes-Correia Armanda E. Santos José B.A. Custódio 《Experimental cell research》2014
Recent reports suggest that N-methyl-d-aspartate receptor (NMDAR) blockade by MK-801 decreases tumor growth. Thus, we investigated whether other ionotropic glutamate receptor (iGluR) antagonists were also able to modulate the proliferation of melanoma cells. On the other hand, the antiestrogen tamoxifen (TAM) decreases the proliferation of melanoma cells, and is included in combined therapies for melanoma. As the efficacy of TAM is limited by its metabolism, we investigated the effects of the NMDAR antagonist MK-801 in combination with TAM and its active metabolites, 4-hydroxytamoxifen (OHTAM) and endoxifen (EDX). The NMDAR blockers MK-801 and memantine decreased mouse melanoma K1735-M2 cell proliferation. In contrast, the NMDAR competitive antagonist APV and the AMPA and kainate receptor antagonist NBQX did not affect cell proliferation, suggesting that among the iGluR antagonists only the NMDAR channel blockers inhibit melanoma cell proliferation. The combination of antiestrogens with MK-801 potentiated their individual effects on cell biomass due to diminished cell proliferation, since it decreased the cell number and DNA synthesis without increasing cell death. Importantly, TAM metabolites combined with MK-801 promoted cell cycle arrest in G1. Therefore, the data obtained suggest that the activity of MK-801 and antiestrogens in K1735-M2 cells is greatly enhanced when used in combination. 相似文献
994.
995.
Anthony B. Mak Mariana Pehar Allison M.L. Nixon Rashida A. Williams Andrea C. Uetrecht Luigi Puglielli Jason Moffat 《Journal of molecular biology》2014
The CD133 cell-surface protein expresses the AC133 epitope that is associated with cancer progenitor cells and cancer resistance to traditional anticancer therapies. We report that the endoplasmic reticulum Golgi intermediate compartment residing acetyltransferases, ATase1 (NAT8B) and ATase2 (NAT8), can physically interact with CD133 to acetylate the protein on three lysine residues predicted to reside on the first extracellular loop of CD133. Site-directed mutagenesis of these residues mimicking a loss of acetylation and downregulation or inhibition of ATase1/ATase2 resulted in near-complete abolishment of CD133 protein expression. We also demonstrate that targeting ATase1/ATase2 results in apoptosis of CD133 expressing acute lymphoblastic leukemia cells. Taken together, we suggest that lysine acetylation on predicted extracellular residues plays a key role in expression and trafficking of CD133 protein to the cell surface and can be targeted to disrupt CD133 regulation and function. 相似文献
996.
Mariana Feltrin Canever Luisa Lemos Vieira Carolina Reck Luisa Richter Luiz Claudio Miletti 《The Korean journal of parasitology》2014,52(5):507-511
Outbreaks of tick-borne disease cases in Santa Catarina, Brazil are known, but the presence of the pathogen DNA has never been determined. In this study, the first survey of Anaplasma marginale, Babesia bigemina, and Babesia bovis DNA on blood samples of 33 cattle from an outbreak in Ponte Alta Municipality, Santa Catarina, Brazil, has been carried out. A multiplex PCR detected 54.5% of animals were co-infected with 2 or 3 parasites, while 24.2% were infected with only 1 species. The most prevalent agent was B. bigemina (63.6%) followed by A. marginale (60.6%). This is the first report of tick-borne disease pathogens obtained by DNA analysis in Southern Brazil. 相似文献
997.
998.
Anielle de Pina-Costa Patrícia Brasil Sílvia Maria Di Santi Mariana Pereira de Araujo Martha Cecilia Suárez-Mutis Ana Carolina Faria e Silva Santelli Joseli Oliveira-Ferreira Ricardo Louren?o-de-Oliveira Cláudio Tadeu Daniel-Ribeiro 《Memórias do Instituto Oswaldo Cruz》2014,109(5):618-633
Brazil, a country of continental proportions, presents three profiles of malaria
transmission. The first and most important numerically, occurs inside the Amazon. The
Amazon accounts for approximately 60% of the nation’s territory and approximately 13%
of the Brazilian population. This region hosts 99.5% of the nation’s malaria cases,
which are predominantly caused by Plasmodium vivax (i.e., 82% of
cases in 2013). The second involves imported malaria, which corresponds to malaria
cases acquired outside the region where the individuals live or the diagnosis was
made. These cases are imported from endemic regions of Brazil (i.e., the Amazon) or
from other countries in South and Central America, Africa and Asia. Imported malaria
comprised 89% of the cases found outside the area of active transmission in Brazil in
2013. These cases highlight an important question with respect to both therapeutic
and epidemiological issues because patients, especially those with falciparum
malaria, arriving in a region where the health professionals may not have experience
with the clinical manifestations of malaria and its diagnosis could suffer dramatic
consequences associated with a potential delay in treatment. Additionally, because
the Anopheles vectors exist in most of the country, even a single
case of malaria, if not diagnosed and treated immediately, may result in introduced
cases, causing outbreaks and even introducing or reintroducing the disease to a
non-endemic, receptive region. Cases introduced outside the Amazon usually occur in
areas in which malaria was formerly endemic and are transmitted by competent vectors
belonging to the subgenus Nyssorhynchus (i.e., Anopheles
darlingi, Anopheles aquasalis and species of the Albitarsis complex). The
third type of transmission accounts for only 0.05% of all cases and is caused by
autochthonous malaria in the Atlantic Forest, located primarily along the
southeastern Atlantic Coast. They are caused by parasites that seem to be (or to be
very close to) P. vivax and, in a less extent, by Plasmodium
malariae and it is transmitted by the bromeliad mosquito
Anopheles (Kerteszia) cruzii. This paper deals mainly with the two
profiles of malaria found outside the Amazon: the imported and ensuing introduced
cases and the autochthonous cases. We also provide an update regarding the situation
in Brazil and the Brazilian endemic Amazon. 相似文献
999.
1000.
Mariana Gil Rubén Bottini Mariela Pontin Federico J. Berli María Victoria Salomon Patricia Piccoli 《Plant Growth Regulation》2014,74(2):193-197
Ultraviolet-B solar radiation (UV-B) is an environmental signal with biological effects in different plant tissues. Recent investigations reported dramatic changes of terpenes with a protective role in plant tissues submitted to biotic and abiotic stresses. This study examined the volatile organic compounds (VOCs) profile in flowers of Vitis vinifera L. cv. Malbec under filtered UV-B (or not). Gas chromatography–electron impact mass spectrometry analysis of flowers resulted in the identification of 12 VOCs, including eight sesquiterpenes, two aldehydes, and two ketones, being the oxygenated sesquiterpene farnesol the most abundant. The total amount of VOCs in flowers did not change irrespective UV-B had been filtered or not, suggesting those compounds have a protective role that is constitutive of the reproductive tissues. However UV-B increases the proportion of valencene, β-farnesene, α-panasinsene and hepatriacontanedione which would require further investigation. 相似文献