Metabolism of Δ24-sterols by yeast mutants blocked in removal of the C-14 methyl group

1978 ◽  
Vol 56 (8) ◽  
pp. 794-800 ◽  
Author(s):  
A. M. Pierce ◽  
R. B. Mueller ◽  
A. M. Unrau ◽  
A. C. Oehlschlager
Keyword(s):  
Normal Growth ◽  
Resistant Mutant ◽  
Growth Conditions ◽  
Methyl Group ◽  
Substrate Preferences ◽  
Minor Metabolite ◽  
Methyl Sterols ◽  
A Minor ◽  
Yeast Mutants ◽  
Sterol Methyltransferase

We have investigated the metabolism of exogenously provided Δ24-sterols by whole cell cultures of a polyene-resistant mutant (D10) of Candida albicans blocked at removal of the C-14 methyl group. Comparison of the relative efficiencies of transmethylation at C-24 of selected sterol substrates revealed the following substrate preferences of the Candida Δ24-sterol methyltransferase (EC 2.1.1.41): zymosterol > 4α-methylzymosterol > 14α-methylzymosterol. Exogenous 4,4-dimethylzymosterol was not transmethylated by mutant D10. Incorporation of the 14C-labelled methyl group of S-adenosyl-L-[methyl-14C]methionine into the sterols of a D10 culture preloaded with zymosterol indicated that zymosterol was a better (40 ×) substrate than endogenous lanosterol. Feeding zymosterol to D10 and a polyene-resistant strain of Saccharomyces cerevisiae (Nys-P100) that was also blocked at removal of the C-14 methyl group gave 24-methyl sterols possessing Δ22 and ring B unsaturation. Mutant D10 was able to produce ergosterol from zymosterol whereas Nys-P100 produced ergosta-7,22-dienol. When grown in the presence of 3 μM 25-aza-24,25-dihydrozymosterol, a known inhibitor of the Δ24-sterol methyltransferase, Nys-P100 accumulated 14α-methylzymosterol, a minor metabolite in this mutant under normal growth conditions and hitherto unidentified as a yeast sterol.

scholarly journals Versatile Physiological Functions of Plant GSK3-Like Kinases

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 697
Author(s):  
Juan Mao ◽  
Wenxin Li ◽  
Jing Liu ◽  
Jianming Li
Keyword(s):  
Stress Responses ◽  
Glycogen Synthase ◽  
Plant Stress ◽  
Normal Growth ◽  
Growth Conditions ◽  
Genetic Studies ◽  
Physiological Functions ◽  
Environmental Signals ◽  
Plant Stress Responses ◽  
Diverse Plant

The plant glycogen synthase kinase 3 (GSK3)-like kinases are highly conserved protein serine/threonine kinases that are grouped into four subfamilies. Similar to their mammalian homologs, these kinases are constitutively active under normal growth conditions but become inactivated in response to diverse developmental and environmental signals. Since their initial discoveries in the early 1990s, many biochemical and genetic studies were performed to investigate their physiological functions in various plant species. These studies have demonstrated that the plant GSK3-like kinases are multifunctional kinases involved not only in a wide variety of plant growth and developmental processes but also in diverse plant stress responses. Here we summarize our current understanding of the versatile physiological functions of the plant GSK3-like kinases along with their confirmed and potential substrates.

scholarly journals Sequence and regulation of a gene encoding a human 89-kilodalton heat shock protein.

1989 ◽  
Vol 9 (6) ◽  
pp. 2615-2626 ◽  
Author(s):  
E Hickey ◽  
S E Brandon ◽  
G Smale ◽  
D Lloyd ◽  
L A Weber
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Normal Growth ◽  
Gene Families ◽  
Growth Conditions ◽  
Complete Sequence ◽  
Start Codon ◽  
Hybridization Probe ◽  
Reading Frame ◽  
Alpha Gene

Vertebrate cells synthesize two forms of the 82- to 90-kilodalton heat shock protein that are encoded by distinct gene families. In HeLa cells, both proteins (hsp89 alpha and hsp89 beta) are abundant under normal growth conditions and are synthesized at increased rates in response to heat stress. Only the larger form, hsp89 alpha, is induced by the adenovirus E1A gene product (M. C. Simon, K. Kitchener, H. T. Kao, E. Hickey, L. Weber, R. Voellmy, N. Heintz, and J. R. Nevins, Mol. Cell. Biol. 7:2884-2890, 1987). We have isolated a human hsp89 alpha gene that shows complete sequence identity with heat- and E1A-inducible cDNA used as a hybridization probe. The 5'-flanking region contained overlapping and inverted consensus heat shock control elements that can confer heat-inducible expression on a beta-globin reporter gene. The gene contained 10 intervening sequences. The first intron was located adjacent to the translation start codon, an arrangement also found in the Drosophila hsp82 gene. The spliced mRNA sequence contained a single open reading frame encoding an 84,564-dalton polypeptide showing high homology with the hsp82 to hsp90 proteins of other organisms. The deduced hsp89 alpha protein sequence differed from the human hsp89 beta sequence reported elsewhere (N. F. Rebbe, J. Ware, R. M. Bertina, P. Modrich, and D. W. Stafford (Gene 53:235-245, 1987) in at least 99 out of the 732 amino acids. Transcription of the hsp89 alpha gene was induced by serum during normal cell growth, but expression did not appear to be restricted to a particular stage of the cell cycle. hsp89 alpha mRNA was considerably more stable than the mRNA encoding hsp70, which can account for the higher constitutive rate of hsp89 synthesis in unstressed cells.

The positive regulatory function of the 5'-proximal open reading frames in GCN4 mRNA can be mimicked by heterologous, short coding sequences

1988 ◽  
Vol 8 (9) ◽  
pp. 3827-3836
Author(s):  
N P Williams ◽  
P P Mueller ◽  
A G Hinnebusch
Keyword(s):  
Translational Control ◽  
Normal Growth ◽  
Regulatory Elements ◽  
Growth Conditions ◽  
Open Reading Frames ◽  
Regulatory Function ◽  
Yeast Saccharomyces Cerevisiae ◽  
Reading Frame ◽  
Yeast Genes ◽  
Reading Frames

Translational control of GCN4 expression in the yeast Saccharomyces cerevisiae is mediated by multiple AUG codons present in the leader of GCN4 mRNA, each of which initiates a short open reading frame of only two or three codons. Upstream AUG codons 3 and 4 are required to repress GCN4 expression in normal growth conditions; AUG codons 1 and 2 are needed to overcome this repression in amino acid starvation conditions. We show that the regulatory function of AUG codons 1 and 2 can be qualitatively mimicked by the AUG codons of two heterologous upstream open reading frames (URFs) containing the initiation regions of the yeast genes PGK and TRP1. These AUG codons inhibit GCN4 expression when present singly in the mRNA leader; however, they stimulate GCN4 expression in derepressing conditions when inserted upstream from AUG codons 3 and 4. This finding supports the idea that AUG codons 1 and 2 function in the control mechanism as translation initiation sites and further suggests that suppression of the inhibitory effects of AUG codons 3 and 4 is a general consequence of the translation of URF 1 and 2 sequences upstream. Several observations suggest that AUG codons 3 and 4 are efficient initiation sites; however, these sequences do not act as positive regulatory elements when placed upstream from URF 1. This result suggests that efficient translation is only one of the important properties of the 5' proximal URFs in GCN4 mRNA. We propose that a second property is the ability to permit reinitiation following termination of translation and that URF 1 is optimized for this regulatory function.

Application of natural and synthetic polyamines as growth regulators to improve the freezing tolerance of winter wheat (Triticum aestivum L.)

2012 ◽  
Vol 60 (1) ◽  
pp. 1-10 ◽  
Author(s):  
D. Todorova ◽  
I. Sergiev ◽  
V. Alexieva
Keyword(s):  
Winter Wheat ◽  
Foliar Application ◽  
Normal Growth ◽  
Triticum Aestivum L ◽  
Growth Conditions ◽  
Freezing Stress ◽  
Preliminary Treatment ◽  
Fresh Weight ◽  
Soil Culture ◽  
Weight Losses

Wheat cultivars were grown as soil culture under normal growth conditions. Twoweek- old seedlings were exposed to 4°C for 6 h and then transferred to −12°C for 24 h in the dark. Twenty-four hours before freezing stress, some of the plants were sprayed with aqueous solutions of spermine, spermidine, putrescine, 1,3-diaminopropane (1,3-DAP) and diethylenetriamine (DETA). The data showed that freezing stress caused a decrease in the fresh weight, chlorophyll content and plant survival rate, accompanied by a simultaneous accumulation of free proline and the enhanced leakage of electrolytes. Preliminary treatment with polyamines caused a decline in electrolyte leakage and a considerable augmentation in proline quantity, indicating that the compounds are capable of preventing frost injury. Additionally, the foliar application of polyamines retarded the destruction of chlorophyll, and lessened fresh weight losses due to freezing stress. The synthetic triamine DETA was the most effective, having the most pronounced action in all the experiments, followed by the tetraamine spermine. The application of polyamines to wheat crops could be a promising approach for improving plant growth under unfavourable growth conditions, including freezing temperatures. The results demonstrate that treatment with polyamines could protect winter wheat by reducing the stress injuries caused by subzero temperatures.

scholarly journals Spontaneous Activation of Quiescent Uq Transposable Elements during Endosperm Development in Zea Mays.

Genetics ◽  
1988 ◽  
Vol 119 (2) ◽  
pp. 457-464
Author(s):  
Y B Pan ◽  
P A Peterson
Keyword(s):  
Transposable Elements ◽  
Normal Growth ◽  
Growth Conditions ◽  
Inbred Lines ◽  
Endosperm Development ◽  
Maize Breeding ◽  
Breeding Lines ◽  
Element System ◽  
Aleurone Tissue ◽  
Sufficient Stimulus

Abstract This study addresses the question of the activation of quiescent transposable elements in maize breeding lines. The a-ruq reporter allele of the Uq transposable element system expresses Uq activity (spots or sectors of spots in otherwise colorless aleurone tissue) when exposed to various genotypes of assorted maize inbred lines lacking any active Uq element. This activation of quiescent Uq elements occurs randomly during the growth of the endosperm. It is concluded that there are components in the genome that enhance the rare activation of quiescent Uq elements. Further, it seems that this activation occurs in the absence of any stress-inducing treatment, but that normal growth conditions provide sufficient stimulus for such activation.

scholarly journals Identification and Characterization of Chalcone Isomerase Genes Involved in Flavonoid Production in Dracaena cambodiana

2021 ◽  
Vol 12 ◽  
Author(s):  
Jiahong Zhu ◽  
Wan Zhao ◽  
Rongshuang Li ◽  
Dong Guo ◽  
Huiliang Li ◽  
...  
Keyword(s):  
Transcriptional Profiling ◽  
Normal Growth ◽  
Growth Conditions ◽  
Ultraviolet B ◽  
Chalcone Isomerase ◽  
Enzyme Activity Assay ◽  
Dragon’S Blood ◽  
Dracaena Cambodiana ◽  
Key Enzyme

Dragon’s blood is a traditional medicine in which flavonoids are the main bioactive compounds; however, the underlying formation mechanism of dragon’s blood remains largely poorly understood. Chalcone isomerase (CHI) is the key enzyme in the flavonoid biosynthesis pathway. However, CHI family genes are not well understood in Dracaena cambodiana Pierre ex Gagnep, an important source plant of dragon’s blood. In this study, 11 CHI family genes were identified from D. cambodiana, and they were classified into three types. Evolutionary and transcriptional profiling analysis revealed that DcCHI1 and DcCHI4 might be involved in flavonoid production. Both DcCHI1 and DcCHI4 displayed low expression levels in stem under normal growth conditions and were induced by methyl jasmonate (MeJA), 6-benzyl aminopurine (6-BA, synthetic cytokinin), ultraviolet-B (UV-B), and wounding. The recombinant proteins DcCHI1 and DcCHI4 were expressed in Escherichia coli and purified by His-Bind resin chromatography. Enzyme activity assay indicated that DcCHI1 catalyzed the formation of naringenin from naringenin chalcone, while DcCHI4 lacked this catalytic activity. Overexpression of DcCHI1 or DcCHI4 enhanced the flavonoid production in D. cambodiana and tobacco. These findings implied that DcCHI1 and DcCHI4 play important roles in flavonoid production. Thus, our study will not only contribute to better understand the function and expression regulation of CHI family genes involved in flavonoid production in D. cambodiana but also lay the foundation for developing the effective inducer of dragon’s blood.

scholarly journals Selective Microautophagy of Proteasomes is Initiated by ESCRT-0 and Is Promoted by Proteasome Ubiquitylation

2021 ◽  
Author(s):  
Jianhui Li ◽  
Mark Hochstrasser
Keyword(s):  
Ubiquitin Ligase ◽  
Normal Growth ◽  
Ubiquitin Proteasome System ◽  
Growth Conditions ◽  
Endosomal Sorting ◽  
Glucose Depletion ◽  
Ubiquitin Binding ◽  
Ubiquitin Proteasome ◽  
Low Glucose ◽  
Amp Activated Protein Kinase

The proteasome is central to proteolysis by the ubiquitin-proteasome system under normal growth conditions but is itself degraded through macroautophagy under nutrient stress. A recently described AMPK (AMP-activated protein kinase)-regulated ESCRT (endosomal sorting complex required for transport)-dependent microautophagy pathway also regulates proteasome trafficking and degradation in low glucose conditions in yeast. Aberrant proteasomes are more prone to microautophagy, suggesting the ESCRT system fine-tunes proteasome quality control under low glucose stress. Here we uncover additional features of the selective microautophagy of proteasomes. Genetic or pharmacological induction of aberrant proteasomes is associated with increased mono- or oligo-ubiquitylation of proteasome components, which appear to be recognized by ESCRT-0. AMPK controls this pathway in part by regulating the trafficking of ESCRT-0 to the vacuole surface, which also leads to degradation of the Vps27 subunit of ESCRT-0. The Rsp5 ubiquitin ligase contributes to proteasome subunit ubiquitylation, and multiple ubiquitin-binding elements in Vps27 are involved in their recognition. We propose that ESCRT-0 at the vacuole surface recognizes ubiquitylated proteasomes and initiates their microautophagic elimination during glucose depletion.

scholarly journals Mutation in OsFWL7 Affects Cadmium and Micronutrient Metal Accumulation in Rice

2021 ◽  
Vol 22 (22) ◽  
pp. 12583
Author(s):  
Qingsong Gao ◽  
Lei Liu ◽  
Haiying Zhou ◽  
Xi Liu ◽  
Wei Li ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Molecular Mechanisms ◽  
Metal Accumulation ◽  
Normal Growth ◽  
Growth Conditions ◽  
Membrane Microdomains ◽  
Metal Transporter ◽  
Membrane Microdomain ◽  
Marker Proteins ◽  
Family Gene

Micronutrient metals, such as Mn, Cu, Fe, and Zn, are essential heavy metals for plant growth and development, while Cd is a nonessential heavy metal that is highly toxic to both plants and humans. Our understanding of the molecular mechanisms underlying Cd and micronutrient metal accumulation in plants remains incomplete. Here, we show that OsFWL7, an FW2.2-like (FWL) family gene in Oryza sativa, is preferentially expressed in the root and encodes a protein localized to the cell membrane. The osfwl7 mutation reduces both the uptake and the root-to-shoot translocation of Cd in rice plants. Additionally, the accumulation of micronutrient metals, including Mn, Cu, and Fe, was lower in osfwl7 mutants than in the wildtype plants under normal growth conditions. Moreover, the osfwl7 mutation affects the expression of several heavy metal transporter genes. Protein interaction analyses reveal that rice FWL proteins interact with themselves and one another, and with several membrane microdomain marker proteins. Our results suggest that OsFWL7 is involved in Cd and micronutrient metal accumulation in rice. Additionally, rice FWL proteins may form oligomers and some of them may be located in membrane microdomains.

scholarly journals Bryophytes of the upper reaches of the Western Bug River (Lviv Region, Ukraine)

2020 ◽  
pp. 7-24
Author(s):  
Yura Drach ◽  
Zvenysvala Mamchur
Keyword(s):  
Development Strategy ◽  
Life Forms ◽  
Wetland Ecosystems ◽  
Substrate Preferences ◽  
Ecological Features ◽  
The Development Strategy ◽  
Cold Tolerant ◽  
A Minor ◽  
First Time ◽  
Minor Extent

In the article, the bryophytes of the upper reaches of the Western Bug River, which is physically and geographically located within Male Polissya, partly Roztochia, and to a minor extent in the Gologoro-Voronyatsky denudo-structural hills, have been studied. Based on our survey, a list of the bryophytes has been compiled for the first time. Ecological features, substrate preferences and life forms of the bryophytes have been analysed. According to the ecological features, subheliophytes (30.9%) and hemisciophytes (30.9%) predominate in the spectrum of heliomorphs; mesophytes (29.7%), hygromesophytes (21.2%) and xeromesophytes – in the spectrum of hydromorphs (19.4%); cold-tolerant species (59.4%) – in the spectrum of thermomorphs. Based on the analysis of the substrate preferences of the bryophytes, the following groups were identified: epigeans (116 species), epixils (56 species), epiphytes (46 species), epiliths (43 species), aquatic (22 species). The prevailing life forms are turf (30.3%), rough mat (18.2%), weft (15.2%), tuft (10.3%) and smooth mat (9.7%). 3 species that are officially recognised as rare and 16 species that are recognized as regionally rare have been found. In the group of bryophytes associated with wetland ecosystems, 2 officially rare and 6 regionally rare species were found in the study area. Given the large areas of drained land in Lviv Region, these species are of particular value, especially in the context of conservation of the biodiversity and protection of the valuable natural areas in accordance with the Development Strategy of Lviv Region by 2027.

scholarly journals Identification of Key Genes in ‘Luang Pratahn’, Thai Salt-Tolerant Rice, Based on Time-Course Data and Weighted Co-expression Networks

2021 ◽  
Vol 12 ◽  
Author(s):  
Pajaree Sonsungsan ◽  
Pheerawat Chantanakool ◽  
Apichat Suratanee ◽  
Teerapong Buaboocha ◽  
Luca Comai ◽  
...  
Keyword(s):  
Salt Stress ◽  
Salt Tolerance ◽  
Stress Responses ◽  
Time Course ◽  
Rice Variety ◽  
Enrichment Analysis ◽  
Normal Growth ◽  
Growth Conditions ◽  
Pathway Enrichment Analysis ◽  
Key Genes

Salinity is an important environmental factor causing a negative effect on rice production. To prevent salinity effects on rice yields, genetic diversity concerning salt tolerance must be evaluated. In this study, we investigated the salinity responses of rice (Oryza sativa) to determine the critical genes. The transcriptomes of ‘Luang Pratahn’ rice, a local Thai rice variety with high salt tolerance, were used as a model for analyzing and identifying the key genes responsible for salt-stress tolerance. Based on 3' Tag-Seq data from the time course of salt-stress treatment, weighted gene co-expression network analysis was used to identify key genes in gene modules. We obtained 1,386 significantly differentially expressed genes in eight modules. Among them, six modules indicated a significant correlation within 6, 12, or 48h after salt stress. Functional and pathway enrichment analysis was performed on the co-expressed genes of interesting modules to reveal which genes were mainly enriched within important functions for salt-stress responses. To identify the key genes in salt-stress responses, we considered the two-state co-expression networks, normal growth conditions, and salt stress to investigate which genes were less important in a normal situation but gained more impact under stress. We identified key genes for the response to biotic and abiotic stimuli and tolerance to salt stress. Thus, these novel genes may play important roles in salinity tolerance and serve as potential biomarkers to improve salt tolerance cultivars.

Sign in / Sign up

Export Citation Format

Share Document