Lipoxygenase in bacteria: a horizontal transfer event?
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Amino Acid Sequence↗
Biomedical subjects
M Rocha-Sosa
Publications and source records attributed to M Rocha-Sosa.
A Phaseolus vulgaris lipoxygenase gene expressed in nodules and in Rhizobium tropici inoculated roots.
A genomic clone encoding a common bean lipoxygenase (PvLOX5) was isolated from a Phaseolus vulgaris library. Reverse transcription-polymerase chain reaction analysis revealed that PvLOX5 is expressed during nodule development and in Rhizobium tropici inoculated roots. There was no detectable expression of PvLOX5 in non-inoculated roots, healthy leaves, leaves after Pseudomonas syringae pv. tabaci infection, floral buds or dry seeds.
Amino Acid Sequence↗
The octadecanoid pathway is required for pathogen-induced multi-functional acetyl-CoA carboxylase accumulation in common bean (Phaseolus vulgaris L.).
A partial cDNA clone corresponding to the multi-functional acetyl-CoA carboxylase (ACCase, EC 6.4.1.2) was isolated using RNA extracted from methyl jasmonate (MeJA)-induced common bean cell cultures. Most of this clone corresponds to the 3' untranslated region and it showed high identity to alfalfa and soybean ACCase sequences. Southern hybridization revealed one copy of this gene in the common bean genome. In addition to being induced by MeJA in cell cultures and leaves, ACCase mRNA accumulated after yeast elicitor or Pseudomonas syringae pv tabaci treatment. Inhibitors of the octadecanoid pathway severely reduced ACCase mRNA and protein accumulation induced by yeast elicitor or P. syringae pv tabaci, indicating that jasmonates or a precursor mediate ACCase induction after pathogen infection. These results provide a role for the eukaryotic ACCase during the defense response to pathogens in common bean.
Journal Article↗
Analysis of lipoxygenase mRNA accumulation in the common bean (Phaseolus vulgaris L.) during development and under stress conditions.
Plant lipoxygenases (LOX, EC 1.13.11.12) have been involved in processes such as stress responses and development. The levels of these enzymes and their corresponding mRNAs are modulated during these processes as well as by different effectors such as jasmonic acid (JA), its methyl ester (MeJA) or abscisic acid (ABA). A new lipoxygenase (LOX) cDNA clone, PvLOX2, was isolated from a Phaseolus vulgaris nodule library and used to study the LOX mRNA accumulation pattern in some developmental stages and in plants subjected to hormone and stress treatments. In nodules, LOX mRNA reaches a maximum level around day 14 to 16 after Rhizobium tropici inoculation, as compared with LOX mRNA present in uninoculated and inoculated roots at the same days. LOX antigen is detected in the nodule parenchyma and in the uninfected cells. During germination, bean LOX transcripts start to accumulate 48 h after imbibition, remains at the same level until 72 h after imbibition and then declines. In hypocotyl, LOX mRNA is abundant in the growing region and almost absent in the mature region. After water stress or ABA treatment, this mRNA increases in the mature region and decreases in the growing region. In bean seedlings, LOX mRNA is accumulated in response to some types of stresses such as cold and desiccation. Wounding, MeJA or ABA treatment of mature leaves also induces LOX mRNA accumulation. These results indicate that in common bean plants LOX is required during development and stress conditions.
Amino Acid Sequence↗
CLA1, a novel gene required for chloroplast development, is highly conserved in evolution.
An albino mutant designated cla1-1 (for "cloroplastos alterados', or "altered chloroplasts') has been isolated from a T-DNA-generated library of Arabidopsis thaliana. In cla1-1 plants, chloroplast development is arrested at an early stage. cla1-1 plants behave like wild-type in their capacity to etiolate and produce anthocyanins indicating that the light signal transduction pathway seems to be unaffected. Genetic and molecular analyses show that the disruption of a single gene, CLA1, by the T-DNA insertion is responsible for the mutant phenotype. RNA expression patterns indicate that CLA1 is positively regulated by light and that it has different effects on the steady-state RNA levels of some nuclear- and chloroplast-encoded photosynthetic genes. Although the specific function of the CLA1 gene is still unknown, it encodes a novel protein conserved in evolution between photosynthetic bacteria and plants which is essential for chloroplast development in Arabidopsis.
Amino Acid Sequence↗
Characterization and gene expression of nodulin Npv30 from common bean.
We previously reported that transcripts for a 30-kD nodulin (Npv30) are very abundant in the nodule. In this paper we describe the isolation and characterization of Npv30 cDNA and genomic clones. Npv30 has the following characteristic features: (a) a putative signal sequence at the deduced amino-terminal region, (b) a proline-rich stretch at the carboxy terminus, and (c) a characteristic domain of four cysteines that resemble metal-binding sites. In Phaseolus vulgaris L., Npv30 is encoded by a small gene family that shares discrete sequence homologies with another small gene family in soybean. An antibody against a beta-galactosidase-Npv30 fusion protein detected two proteins of 28 and 30 kD. Although Npv30 transcripts are very abundant, they encode proteins that are hardly detected in nodule fractions, suggesting that these proteins have a short half-life and/or the mRNAs are strongly regulated at the translational level. Npv30 transcripts were detected in the infected cells of the nodule by in situ hybridization experiments.
Amino Acid Sequence↗
The expression of a chimeric Phaseolus vulgaris nodulin 30-GUS gene is restricted to the rhizobially infected cells in transgenic Lotus corniculatus nodules.
In Phaseolus vulgaris there is a nodulin family, Npv30, of ca. 30 kDa, as detected in an in vitro translation assay [2]. We isolated a gene (npv30-1) for one of the members of this family. The nucleotide sequence of the promoter of npv30-1 contains nodule-specific motifs common to other late nodulin genes. The promoter was fused to the GUS reporter gene; this chimeric fusion was introduced into Lotus corniculatus via Agrobacterium rhizogenes transformation. GUS activity was only detected in the infected cells of the nodules of transgenic plants. By contrast, the expression of a 35S-GUS construct was restricted to the uninfected cells and the vascular tissue.
Base Sequence↗
A detailed study of the regulation and evolution of the two classes of patatin genes in Solanum tuberosum L.
The class-specific expression of patatin genes was investigated by analysing four new patatin genes. A class I patatin gene from cv. Berolina as well as a class I and two class II patatin genes from the monohaploid cultivar AM 80/5793 were isolated and partially sequenced. Sequence comparison indicates rearrangements as the major source for the generation of diversity between the different members of the classes. The expression of single genes was studied in potato plants transformed with chimaeric genes where the putative patatin promoters were fused to the GUS reporter gene. A detailed histochemical analysis reveals that both class I genes are expressed as the previously described class I patatin gene B33 from cv. Berolina [1], i.e. in the starch-containing cells of potato tubers and in sucrose-induced leaves. The class II gene pgT12 shows the same pattern as the previously described class II gene pgT2 [2], i.e. expression in root tips and in the vascular tissue of tubers, whereas no activity was detectable for pgT4. Thus the expression pattern of both classes of genes seems to be stable at least within or even between different cultivars.
Base Sequence↗
Gene expression during tuber development in potato plants.
Potato tubers are modified stems that have differentiated into storage organs. Factors such as day-length, nitrogen supply, and levels of the phytohormones cytokinin and gibberellic acid, are known to control tuberization. Morphological changes during tuber initiation are accompanied by the accumulation of a characteristic set of proteins, thought to be involved in N-storage (i.e. patatin) or defense against microbial or insect attack (i.e. proteinase inhibitor II). Additionally, deposition of large amounts of starch occurs during tuber formation, which is paralleled by an increase in sucrose synthase and other enzymes involved in starch biosynthesis (i.e. ADP-glucose pyrophosphorylase, starch synthases, and branching enzyme). Potential controlling mechanisms for genes expressed during tuberization are discussed.
Carboxylic Ester Hydrolases↗
Presence of a transposon-like element in the promoter region of an inactive patatin gene in Solanum tuberosum L.
The promoter of the PGT3 patatin gene belonging to the class II subfamily is highly homologous to other class II patatin genes except for a 736 bp insertion in front of the putative transcription start site. The insertion is characterized by structural features resembling a transposable element such as an 11 bp inverted repeat at the termini and an 8 bp duplication flanking the insertion site. Despite the high homology to active patatin genes, fusion of its promoter to the beta-glucuronidase reporter gene does not lead to detectable beta-glucuronidase (GUS) activity in transgenic potato or tobacco plants, suggesting that the inactivation of this gene might be caused by the insertion of the transposon like element.
Base Sequence↗
Construction of an intron-containing marker gene: splicing of the intron in transgenic plants and its use in monitoring early events in Agrobacterium-mediated plant transformation.
Agrobacterium tumefaciens is a commonly used tool for transforming dicotyledonous plants. The underlying mechanism of transformation however is not very well understood. One problem complicating the analysis of this mechanism is the fact that most indicator genes are already active in Agrobacterium, thereby preventing the precise determination of timing and localisation of T-DNA transfer to plant cells. In order to overcome this obstacle a modified prokaryotic indicator gene was constructed. The expression of this indicator gene and its use in analysing early events in Agrobacterium-mediated plant transformation are described. A portable intron, derived from a plant intron, was introduced into the beta-glucuronidase (GUS) gene. In transgenic plants containing this chimaeric gene the intron is spliced efficiently, giving rise to GUS enzymatic activity. Mapping of the splice junction indicates the exact removal of the intron. No GUS activity is detected in agrobacteria containing this construct due to the lack of a eukaryotic splicing apparatus in prokaryotes. Early phases after transformation of Arabidopsis cotyledon explants were analysed using this GUS-intron chimaeric gene showing that as early as 36 h after Agrobacterium infection significant GUS activity is detected. In vivo GUS staining of transformed cells clearly shows that quickly proliferating calli expressing GUS activity are formed, mainly at the cut surface. Minor transformation events occur however throughout the whole cotyledon. These data indicate that Agrobacterium-mediated T-DNA transfer to plants is much more efficient than has been judged from experiments where selection is applied immediately. The intron-containing GUS gene can be used as an optimised marker gene in transient and stable transformation experiments.
Base Sequence↗
Both developmental and metabolic signals activate the promoter of a class I patatin gene.
Patatin is one of the major soluble proteins in potato tubers and is encoded by a multigene family. Based on structural considerations two classes of patatin genes are distinguished. The 5'-upstream regulatory region of a class I gene contained within a 1.5 kb sequence is essential and sufficient to direct a high level of tuber-specific gene activity which was on average 100- to 1000-fold higher in tubers as compared to leaf, stem and roots in greenhouse grown transgenic potato plants when fused to the beta-glucuronidase reporter gene. Histochemical analysis revealed this activity to be present in parenchymatic tissue but not in the peripheral phellem cells of transgenic tubers. Furthermore the promoter fragment can be activated in leaves under conditions that simulate the need for the accumulation of starch in storage organs, i.e. high levels of sucrose. The expression is restricted to both mesophyll and epidermal cells in contrast to vascular tissue or hair cells.
Journal Article↗
A class II patatin promoter is under developmental control in both transgenic potato and tobacco plants.
A new member of the patatin gene family belonging to the class II subfamily was isolated and characterized by DNA sequencing. In order to study the expression profile of this gene, the promoter was fused to the beta-glucuronidase gene and transferred to potato and tobacco. Histochemical analysis revealed high expression in a few defined cells in potato tubers and in a specific layer of both potato and tobacco root tips. In contrast to the developmentally and metabolically regulated class I patatin gene B33 this gene was not inducible by elevated levels of sucrose. Expression of this chimaeric gene was also found in callus and suspension cultures of potato.
Base Sequence↗
Analysis of cis-active sequences involved in the leaf-specific expression of a potato gene in transgenic plants.
ST-LS1 is a light-inducible, single-copy gene from potato that is expressed only in photosynthetic tissues. Various sequences derived from the 5'-upstream region of this gene were fused to the coding region of the chloramphenicol acetyltransferase (CAT) gene and to the gene 7 termination region of the transfer DNA (T-DNA) from the Agrobacterium Ti plasmid pTiACH5 and transferred to tobacco using Ti-plasmid vectors. After regeneration of whole plants, tissues were assayed for the expression of the CAT gene. Sequences derived from the 5'-upstream region of the ST-LS1 gene comprising positions -334 to +11 were sufficient to confer a leaf/stem-specific as well as a light-inducible expression of the CAT gene. Destruction of chloroplasts by treatment with the herbicide norfluorazon and subsequent exposure to light drastically reduced the expression of the CAT gene indicating that this upstream sequence most likely interacts with a chloroplast-dependent signal. When sequences from position -98 to position +675 were fused to a truncated inactive fragment of the cauliflower mosaic virus 35S promoter in a head-to-head manner, the corresponding chimeric genes were again expressed in photosynthetic tissues only, indicating that these sequences have enhancer-like properties.
Journal Article↗