PubMed Health⌕ Search

Biomedical subjects

C Fenoll

Publications and source records attributed to C Fenoll.

12 recordsLinked to original sources
PubMed1999

Isolation of the LEMMI9 gene and promoter analysis during a compatible plant-nematode interaction.

Plant-endoparasitic root-knot nematodes feed on specialized giant cells that they induce in the vascular cylinder of susceptible plants. Although it has been established that a number of plant genes change their expression pattern during giant cell differentiation, virtually no data are available about the mechanisms involved in that change. One possibility is differential promoter recognition by the transcription factor(s) responsible for the expression of specific genes. We have isolated and characterized a genomic clone from tomato containing the promoter region of LEMMI9, one of the few plant genes that have been reported to be highly expressed in galls (predominantly in giant cells). The analysis of transgenic potato plants carrying a LEMMI9 promoter-beta glucuronidase (GUS) fusion has demonstrated that the tomato promoter was activated in Meloidogyne incognita-induced galls in a heterologous system. We have located putative regulatory sequences in the promoter and have found that nuclear proteins from the galls formed specific DNA-protein complexes with the proximal region of the LEMMI9 promoter. The nuclear protein-binding sequence mapped to a region of 111 bp immediately upstream from the TATA box. This region contains a 12-bp repeat possibly involved in the formation of DNA-protein complexes, which might be related to the LEMMI9 transcriptional activation in the giant cells.

Animals↗
PubMed1997

Tracing the ontogeny of stomatal clusters in Arabidopsis with molecular markers.

The origin and process by which the mosaic of the different cell types is established during the development of the leaf epidermis in Arabidopsis are largely unknown, although the recent characterization of two mutants which develop stomatal clusters (four lips (flp) and too many mouths (tmm)) has opened up the possibility for genetic dissection of the stomata spacing. By using growth conditions which limit gas exchange with the open atmosphere, stomatal clusters that look like phenocopies of flp and tmm have been induced, suggesting that stomata spacing is under environmental as well as genetic control in Arabidopsis. The origin of these clusters has been addressed by following promoter activity for genes that are markers for competence for cell division (cdc2aAt), mitotic activity (cyc1aAt), and guard mother cell and developing guard cell identity (rha1). Their different expression patterns in the various cell types during epidermal differentiation and the asynchrony in the development of the various stomata that constitute each cluster suggest that these stomatal clusters derive from a single protodermal cell through a process that involves changes in cell fate in a subset of subsidiary cells. It was also found that guard cells express cdc2aAt and cyc1aAt, supporting the idea that they may remain competent for cell division.

Arabidopsis↗
PubMed1996

The two nonstructural proteins from wheat dwarf virus involved in viral gene expression and replication are retinoblastoma-binding proteins.

Tumor-inducing viruses like simian virus 40 or the human adenovirus produce oncoproteins which interfere with the cellular retinoblastoma (Rb) tumor-suppressor protein to create an appropriate molecular environment in the nucleus for viral transcription and replication. Such a strategy has been considered to be restricted to animal viruses. Here we demonstrate that plant viruses may use similar mechanisms for recruiting host factors. Wheat dwarf virus (WDV) encodes two potential nonstructural proteins, C1 and C1:C2, both containing the consensus Rb-binding motif LeuXCysXGlu that allows the oncoproteins from animal viruses to inactivate Rb. C1:C2 is a key determinant of viral replication and V(virion)-sense expression. Using a yeast two-hybrid protein assay, we demonstrate for the first time that the C1:C2 protein from WDV interacts with a retinoblastoma protein, providing an explanation for the previously observed dependence of viral replication on an intact Rb-binding motif. We also show that C1, for which no function had been demonstrated, is required for V-sense gene expression. This suggests that V-sense expression might be dependent on the interaction of C1 with Rb. Our findings provide further evidence for the presence of transforming-like proteins in a plant virus and will help to explain the production of symptoms in a plant viral infection through a mechanism mediated by a key regulator of cell cycle and differentiation.

Amino Acid Sequence↗
PubMed1990

The intergenic region of maize streak virus contains a GC-rich element that activates rightward transcription and binds maize nuclear factors.

Maize streak virus (MSV) is transcribed bidirectionally from an intergenic region and rightward transcription produces an RNA that encodes the coat protein. The intergenic region contains promoter elements required for rightward transcription including an upstream activating sequence (UAS) which endows the promoter with full activity in a maize transient expression system. The UAS contains two GC-rich repeats (GC boxes) and a long inverted repeat or hairpin with a loop harboring a TAATATTAC sequence common to all geminiviruses. Deletions through the UAS demonstrated the presence of an element, called the rightward promoter element (rpe1), which is responsible for transcriptional activation. Rpe1 includes the two GC-rich boxes, which are similar in sequence to Sp1 binding sites in mammalian cells, but not the conserved hairpin loop. Rpe1 binds maize nuclear factors in vitro and the characteristics of the binding interaction have been determined by 1) binding competition with oligonucleotides, 2) methidiumpropyl-EDTA footprinting and 3) methylation interference assays. Binding of maize nuclear factors to the UAS generates two major bands, slow and fast migrating bands, in gel retardation assays. Footprinting and factor titration data suggest that the fast bands arise by the binding of factors to one GC box while the slow bands are generated by factors binding to both boxes. The data further indicate that the factors bind to the two GC-rich boxes with little cooperativity and bind on opposite faces of the DNA helix.

Base Sequence↗
PubMed1988

The intergenic region of maize streak virus contains promoter elements involved in rightward transcription of the viral genome.

Maize streak virus (MSV), a geminivirus with a one-component genome, encodes a major coat protein RNA which accumulates in infected plants. Using a maize protoplast cell transient expression system, we have defined and studied the promoter which drives rightward transcription of the RNA encoding the coat protein. We have identified a 122 bp upstream segment that enhances promoter activity and functions as an upstream activating sequence (UAS). The UAS lies in the starting intergenic region of the viral genome and includes a region which is similar in all geminiviruses. The 122 bp UAS activates the MSV core promoter in an orientation, but not position, independent fashion. The MSV promoter UAS is interchangeable with a similar element in the cauliflower mosaic virus (CaMV) 35S RNA core promoter, that is the MSV UAS will activate the CaMV 35S core promoter and vice versa. However, the MSV promoter UAS specifically binds proteins in maize nuclear extracts which appear to differ from those bound by the functionally equivalent region of the CaMV 35S promoter.

Journal Article↗
PubMed1987

Construction and Homologous Expression of a Maize Adh1 Based NcoI Cassette Vector.

The alcohol dehydrogenase I (Adh1) gene of maize (Zea mays L.) was employed as a source of transcriptional, posttranscriptional, and translational regulatory sequences in the construction of an expression vector. By transforming the translation-initiating ATG and an ATG three triplets upstream from the translational termination triplet into NcoI sites (5'-CCATGG-3'), the maize Adh1 gene was converted into a cassette vector allowing one-step placement of any structural gene under Adh1 regulatory control. We inserted the structural gene for chloramphenicol acetyl transferase (CAT) into this cassette vector and found that this construct expressed the cat gene when transfected into maize protoplasts. Significant expression was observed with a construct that contained only 146 base pairs of Adh1 sequence upstream of the transcription-initiation site. Derivatives with a further 266 or 955 base pairs of contiguous Adh1 upstream sequences increased CAT expression approximately 5-fold or 8-fold, respectively.

Journal Article↗
PubMed1986

Purification of a light-harvesting B880 complex from wild-type Rhodospirillum rubrum.

The light-harvesting B880 complex of Rhodospirillum rubrum was purified by a new method which allowed recovery of 66% of the amount present in the crude solubilized extract. Electrophoretic analysis of the isolated complex, followed by either Coomassie brilliant blue or silver staining, revealed only two low-molecular-weight polypeptides. When compared to a previously described preparation, the stability of the complex was considerably increased. In addition, the new procedure yielded B880 of higher purity as evidenced both by the decreased protein to pigment ratio (A280/A880 = 0.4) and by the absence of contaminants previously detected by silver staining or by an immunochemical method in other preparations. The most prominent of those contaminants were identified in this work as lipopolysaccharides of the bacterial outer membrane.

Bacterial Proteins↗
PubMed1985

Influence of the genetic background on cell division and cell lysis: behaviour of different Escherichia coli strains carrying the ts-52 or the ftsA-3 mutation.

The analysis of Escherichia coli strains harbouring division mutations, namely the ts-52 or the ftsA-3 division alleles, in different genetic backgrounds showed that treatment with chloramphenicol in cells incubated at the restrictive temperature induced either cell lysis (ts-52 and ftsA-3 in MC-6 genetic background) or cell division (ts-52 in OV-2 genetic background). This chloramphenicol treatment of ftsA-3 filaments (previously designated at divA) does not induce cell division but does induce cell lysis.

Alleles↗