2 research outputs found
Caracterizaci贸n enzim谩tica de la RNA helicasa CI del virus de la sharka (PPV) y su funci贸n en el ciclo de infecci贸n viral
Tesis doctoral in茅dita le铆da en la Universidad Aut贸noma de Madrid, Facultad de Ciencias, Departamento de Biolog铆a Molecular, Fecha de lectura 31-03-2004Potyviruses are positive-strand RNA viruses that encode nine or more mature proteins
fmm a polyprotein expression strategy. One unique feature of the potyvims infection is
the accumulation of characteristic pinwheel-shaped cytoplasmic inclusion bodies. The
plum pox potyvirus (PPV) protein CI is an RNA helicase which is involved in
replication and cell to cell spread of the virus. However, relationships among the
enzymatic activities, assembly in inclusion bodies, and CI functions in the viral cycle,
are not well established.
The CI protein contains seven conserved sequence motifs Srpical of RNA helicases of
the superfamily SF2. There is great controversy about the function of the VI motif in the
enzymatic activity of the protein. We have introduced several individual point
mutations into the sequence that coda for the motif VI of the PPV CI protein and we
have expressed these mutant proteins in Escherichia coli as maltose binding protein
fusion products. Our results seem to indicate that this motif is implicated in the direct
interaction with the NTP instead that with the nucleic acid interaction.
Moreover we also show that the protein exists in solution as a group of different
aggregated forms and that the oligomerization of the protein is required for an efficient
RNA helicase activity. Inhibition of the CI wild type RNA helicase activity by negative
mutants of the protein, it gives a further evidence about the importance of
oligomerization in the helicase of the protein.
The systemic infection of the plant by viruses generally requires the virus to be able to
move from cell to cell through plasmodesmata and to long distances through the
phloem. Normally, the cell-to-cell movement requires specialized proteins w), which
facilitate intra- and inter-cellular transport of the virus or nucleoprotein complexes.
Several types of MP have been characterized: (i) Some viruses, such as tobacco mosaic
virus and red clover necrotic mosaic virus, encode single dedicated MPs that modify
plasmodesmata and facilitate transport of themselves and nucleic acids through the
modified channel; (ii) Several families of viruses contain a set of movement genes
called the triple gene block, which encodes three proteins that are proposed to function
co-ordinately to transport genomes through plasmodesmata; (iii) Finally, some other
groups of viruses encode MPs that form plasmodesmal associated tubules through
which virus or transport complexes travel. In contrast to most other viruses, the
potyviruses do not encode a dedicated MP. Rather, potyvinis movement involves vira1
proteins that perform additional roles in the viral infection cycle. It is known that cellto-
cell transport requires the assembly of competent capsid protein (CP), suggesting that
intercellular transport involves Wion formation. At early times post-infection, the CI
protein is associated with cone-shaped structures anchored to the cell wall or with
plasma membrane in close proximity to plasmodesmata. In addition to the CI protein,
these plasmodesmal-associated structures contain CP and viral RNA. So these
observations led to propose that the CI protein could facilitate the cell-to-cell movement
of the virus through direct interactions or modifications of plasmodesmata. Fially
genetic analysis data demonstrated the involvement of the CI protein of TEV in cell-tocell
movement.
Regardless of wether or not the helicase activity of the CI protein is required or not for
the cell-to-cell movement, in this study, we show strong evidence about an structural
implication of the CI protein on the vira1 cell-to-cell movement
Coordinate 尾-adrenergic inhibition of mitochondrial activity and angiogenesis arrest tumor growth
Mitochondrial metabolism has emerged as a promising target against the mechanisms of tumor growth. Herein, we have screened an FDA-approved library to identify drugs that inhibit mitochondrial respiration. The 尾1-blocker nebivolol specifically hinders oxidative phosphorylation in cancer cells by concertedly inhibiting Complex I and ATP synthase activities. Complex I inhibition is mediated by interfering the phosphorylation of NDUFS7. Inhibition of the ATP synthase is exerted by the overexpression and binding of the ATPase Inhibitory Factor 1 (IF1) to the enzyme. Remarkably, nebivolol also arrests tumor angiogenesis by arresting endothelial cell proliferation. Altogether, targeting mitochondria and angiogenesis triggers a metabolic and oxidative stress crisis that restricts the growth of colon and breast carcinomas. Nebivolol holds great promise to be repurposed for the treatment of cancer patients.FPI-MINECO and Fondo Social Europeo. L.F. received support from the Ram贸n y Cajal Program (RyC-2013-13693). The work was supported by grants from MINECO (SAF2016-75916-R and PID2019-108674RB-100), CIBERER-ISCIII (CB06/07/0017) and Fundaci贸n Ram贸n Arece