The enzymes forming isopentenyl pyrophosphate from 5-phosphomevalonate (mevalonate 5-phosphate) in the latex of Hevea brasiliensis.
Ontology highlight
ABSTRACT:
SUBMITTER: Skilleter DN
PROVIDER: S-EPMC1177155 | biostudies-other | 1971 Sep
REPOSITORIES: biostudies-other
Similar Datasets
Project description:1. Evidence has been produced for the formation of 5-phosphomevalonate from potassium dl-mevalonate by the latex of Hevea brasiliensis and by reconstituted freeze-dried serum obtained from this latex. 2. The enzyme, mevalonate kinase, catalysing the formation of 5-phosphomevalonate from potassium dl-mevalonate and ATP has been partially purified. 3. 5-Phosphomevalonate formed by the purified mevalonate kinase from potassium [2-(14)C]mevalonate has been shown to be incorporated by latex into rubber to about 2.4 times the extent of dl-mevalonate. 4. The enzyme can utilize inosine triphosphate as effectively as adenosine triphosphate as a phosphate donor and is also slightly active with uridine triphosphate. 5. The enzyme was fairly stable to a range of pH values and temperatures, the activity being optimum at pH7.5 and 60-70 degrees . The energy of activation was 10.7kcal./mole. The K(m) values were 0.13mm for potassium dl-mevalonate and 2.0mm for ATP at 30 degrees . 6. The enzyme required the presence of Mn(2+) (1mm) for maximum activity; this could be replaced by Mg(2+) (4mm), which was less effective, and by Ca(2+), which was far less effective. 6. Although the enzyme did not require cysteine or reduced glutathione for activation in aerobic conditions, it was inhibited by reagents known to react with thiol groups.
| S-EPMC1207229 | biostudies-other
Project description:Latex exploitation enhances latex regeneration in rubber trees. The latex exploitation-caused latex flow lasts from 10 min to a few hours, which is convenient for exploring the transcript profiling of latex metabolism-related genes at the different stages of latex flow. In the present study, the expression pattern of 62 latex metabolism-related genes involved in water transportation, carbohydrate metabolism, natural rubber biosynthesis, hormone signaling, ROS generation and scavenging, and latex coagulum across three stages of latex flow between rubber tree clones CATAS7-33-97 and CATAS8-79 were comparatively analyzed by quantitative real-time PCR. The two clones show differences in latex regeneration and have a different duration of latex flow. The results showed that the expression levels of 38 genes were significantly higher in CATAS8-79 latex than in CATAS7-33-97 during latex regeneration, while 45 genes had a notably higher expression level in CATAS8-79 latex during latex flow. Together with the activation of the MEP pathway and jasmonate pathway in CATAS8-79 latex, HbPIP1;3, HbPIP1;4, HbSUT3, HbSus3, HbHMGS1-2, HbMK should contribute to the high latex regeneration ability. The up-regulation of ethylene signaling and Hb44KD and the down-regulation of latex coagulation-related genes in CATAS8-79 latex might contribute to its longer latex flow duration. This study provides some cues for revealing the regulation of latex metabolism in rubber trees.
| S-EPMC5682034 | biostudies-literature
Project description:The cytosolic mevalonate (MVA) pathway in Hevea brasiliensis latex is the conventionally accepted pathway which provides isopentenyl diphosphate (IPP) for cis-polyisoprene (rubber) biosynthesis. However, the plastidic 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway may be an alternative source of IPP since its more recent discovery in plants. Quantitative RT-PCR (qRT-PCR) expression profiles of genes from both pathways in latex showed that subcellular compartmentalization of IPP for cis-polyisoprene synthesis is related to the degree of plastidic carotenoid synthesis. From this, the occurrence of two schemes of IPP partitioning and utilization within one species is proposed whereby the supply of IPP for cis-polyisoprene from the MEP pathway is related to carotenoid production in latex. Subsequently, a set of latex unique gene transcripts was sequenced and assembled and they were then mapped to IPP-requiring pathways. Up to eight such pathways, including cis-polyisoprene biosynthesis, were identified. Our findings on pre- and post-IPP metabolic routes form an important aspect of a pathway knowledge-driven approach to enhancing cis-polyisoprene biosynthesis in transgenic rubber trees.
| S-EPMC3295384 | biostudies-literature
Project description:1. The microfibrils contained within the lutoid particles of Hevea brasiliensis latex obtained from young tissue have been isolated by methods based on low-speed centrifugation, isoelectric precipitation and gel filtration. 2. The isolated microfibrils behave as a single protein having an isoelectric point of about 4 as determined by paper electrophoresis. 3. The only components so far detected in the microfibrils are protein and possibly carbohydrate; nucleic acid appears to be absent. 4. The amino acid composition of the microfibril protein shows no unusual features. 5. In latex from the more mature laticiferous tissues of H. brasiliensis, the lutoid particles appear to be devoid of microfibrils or their protein decomposition products.
| S-EPMC1264836 | biostudies-other
Project description:Background:Small RNAs modulate plant gene expression at both the transcriptional and post-transcriptional level, mostly through the induction of either targeted DNA methylation or transcript cleavage, respectively. Small RNA networks are involved in specific plant developmental processes, in signaling pathways triggered by various abiotic stresses and in interactions between the plant and viral and non-viral pathogens. They are also involved in silencing maintenance of transposable elements and endogenous viral elements. Alteration in small RNA production in response to various environmental stresses can affect all the above-mentioned processes. In rubber trees, changes observed in small RNA populations in response to trees affected by tapping panel dryness, in comparison to healthy ones, suggest a shift from a transcriptional to a post-transcriptional regulatory pathway. This is the first attempt to characterise small RNAs involved in post-transcriptional silencing and their target transcripts in Hevea. Methods:Genes producing microRNAs (MIR genes) and loci producing trans-activated small interfering RNA (ta-siRNA) were identified in the clone PB 260 re-sequenced genome. Degradome libraries were constructed with a pool of total RNA from six different Hevea tissues in stressed and non-stressed plants. The analysis of cleaved RNA data, associated with genomics and transcriptomics data, led to the identification of transcripts that are affected by 20-22 nt small RNA-mediated post-transcriptional regulation. A detailed analysis was carried out on gene families related to latex production and in response to growth regulators. Results:Compared to other tissues, latex cells had a higher proportion of transcript cleavage activity mediated by miRNAs and ta-siRNAs. Post-transcriptional regulation was also observed at each step of the natural rubber biosynthesis pathway. Among the genes involved in the miRNA biogenesis pathway, our analyses showed that all of them are expressed in latex. Using phylogenetic analyses, we show that both the Argonaute and Dicer-like gene families recently underwent expansion. Overall, our study underlines the fact that important biological pathways, including hormonal signalling and rubber biosynthesis, are subject to post-transcriptional silencing in laticifers.
| S-EPMC7195832 | biostudies-literature
Project description:Hevea brasiliensis Müll. Arg. is one of the most frequently wounded plants worldwide. Expelling latex upon mechanical injury is a wound response of rubber trees. However, JA-mediated wound responses in rubber trees are not well documented. In this work, three JAZ-interacting MYC transcription factors of H. brasiliensis (termed HbMYC2/3/4) were identified by yeast two-hybrid screening. HbMYC2/3/4 each showed specific interaction profiles with HbJAZs. HbMYC2/3/4 each localized in the nucleus and exhibited strong transcriptional activity. To identify the target genes potentially regulated by HbMYC2/3/4, cis-elements interacting with HbMYC2/3/4 were first screened by yeast one-hybrid assays; the results indicated that HbMYC2/3/4 each could bind G-box elements. Additional analysis confirmed that HbMYC2/3/4 bound the HbPIP2;1 promoter, which contains five G-box cis-elements, and regulated the expression of reporter genes in yeast cells and in planta. HbMYC2/3/4 were induced by exogenous JA treatment but suppressed by ethylene (ET) treatment; in contrast, HbPIP2;1 was positively regulated by ET but negatively regulated by JA treatment. Given that HbPIP2;1 is involved in latex drainage, it could be proposed that HbMYC2/3/4 are involved in the regulation of HbPIP2;1 expression as well as latex drainage, both of which are coordinated by the JA and ET signalling pathways.
| S-EPMC5772448 | biostudies-literature
Project description:Ethephon, an ethylene releaser, is used to stimulate latex production in Hevea brasiliensis. Ethylene induces many functions in latex cells including the production of reactive oxygen species (ROS). The accumulation of ROS is responsible for the coagulation of rubber particles in latex cells, resulting in the partial or complete stoppage of latex flow. This study set out to assess biochemical and histological changes as well as changes in gene expression in latex and phloem tissues from trees grown under various harvesting systems. The Tapping Panel Dryness (TPD) susceptibility of Hevea clones was found to be related to some biochemical parameters, such as low sucrose and high inorganic phosphorus contents. A high tapping frequency and ethephon stimulation induced early TPD occurrence in a high latex metabolism clone and late occurrence in a low latex metabolism clone. TPD-affected trees had smaller number of laticifer vessels compared to healthy trees, suggesting a modification of cambial activity. The differential transcript abundance was observed for twenty-seven candidate genes related to TPD occurrence in latex and phloem tissues for ROS-scavenging, ethylene biosynthesis and signalling genes. The predicted function for some Ethylene Response Factor genes suggested that these candidate genes should play an important role in regulating susceptibility to TPD.
| S-EPMC4581227 | biostudies-literature
Project description:Natural rubber is usually synthesized in the rubber particles present in the latex of rubber-producing plants such as the Pará rubber tree (Hevea brasiliensis) and rubber dandelion (Taraxacum kok-saghyz). Since the detailed lipid compositions of fresh latex and rubber particles of the plants are poorly known, the present study reports detailed compound lipid composition, focusing on phospholipids and galactolipids in the latex and rubber particles of the plants. In the fresh latex and rubber particles of both plants, phospholipids were much more dominant (85-99%) compared to galactolipids. Among the nine classes of phospholipids, phosphatidylcholines (PCs) were most abundant, at ~80%, in both plants. Among PCs, PC (36:4) and PC (34:2) were most abundant in the rubber tree and rubber dandelion, respectively. Two classes of galactolipids, monogalactosyl diacylglycerol and digalactosyl diacylglycerol, were detected as 12% and 1%, respectively, of total compound lipids in rubber tree, whereas their percentages in the rubber dandelion were negligible (< 1%). Overall, the compound lipid composition differed only slightly between the fresh latex and the rubber particles of both rubber plants. These results provide fundamental data on the lipid composition of rubber particles in two rubber-producing plants, which can serve as a basis for artificial rubber particle production in the future.
| S-EPMC7662343 | biostudies-literature
Project description:Hevea brasiliensis is exploited for its latex production, and it is the only viable source of natural rubber worldwide. The demand for natural rubber remains high due its high-quality properties, which synthetic rubber cannot compete with. In this paper, we present transcriptomic data and analysis of three H. brasiliensis clones using tissue from latex and bark tissues collected from 10-year-old plant. The combined, assembled transcripts were mapped onto an H. brasiliensis draft genome. Gene ontology analysis showed that the most abundant transcripts related to molecular functions, followed by biological processes and cellular components. Simple sequence repeats (SSR) and single nucleotide polymorphisms (SNP) were also identified, and these can be useful for selection of parental and new clones in a breeding program. Data generated by RNA sequencing were deposited in the NCBI public repository under accession number PRJNA629890.
| S-EPMC7452566 | biostudies-literature
Project description:Ethylene is commonly used as a latex stimulant of Hevea brasiliensis by application of ethephon (chloro-2-ethylphosphonic acid); however, the molecular mechanism by which ethylene increases latex production is not clear. To better understand the effects of ethylene stimulation on the laticiferous cells of rubber trees, a latex expressed sequence tag (EST)-based complementary DNA microarray containing 2973 unique genes (probes) was first developed and used to analyze the latex gene expression changes at three different time-points after ethephon treatment: 8, 24 and 48 h. Transcript levels of 163 genes were significantly altered with fold-change values ≥ 2 or ≤ –2 (q-value < 0.05) in ethephon-treated compared with control rubber trees. Of the 163 genes, 92 were up-regulated and 71 down-regulated. The microarray results were further confirmed using real-time quantitative reverse transcript-PCR for 20 selected genes.
2016-06-01 | GSE74060 | GEO