scholarly journals Maize Zmcyp710a8 Mutant as a Tool to Decipher the Function of Stigmasterol in Plant Metabolism

2021 ◽  
Vol 12 ◽  
Author(s):  
Siddique I. Aboobucker ◽  
Lucas J. Showman ◽  
Thomas Lübberstedt ◽  
Walter P. Suza
Keyword(s):  
Lipid Bilayers ◽  
Crop Improvement ◽  
Cellular Metabolism ◽  
Sterol Composition ◽  
Membrane Lipid ◽  
Sterol Biosynthesis ◽  
Genetic Enhancement ◽  
Individual Plant ◽  
Plant Metabolism ◽  
Developmental Defects

Sterols are integral components of membrane lipid bilayers in eukaryotic organisms and serve as precursors to steroid hormones in vertebrates and brassinosteroids (BR) in plants. In vertebrates, cholesterol is the terminal sterol serving both indirect and direct roles in cell signaling. Plants synthesize a mixture of sterols including cholesterol, sitosterol, campesterol, and stigmasterol but the signaling role for the free forms of individual plant sterols is unclear. Since stigmasterol is the terminal sterol in the sitosterol branch and produced from a single enzymatic step, modifying stigmasterol concentration may shed light on its role in plant metabolism. Although Arabidopsis has been the model of choice to study sterol function, the functional redundancy of AtCYP710A genes and the presence of brassicasterol may hinder our ability to test the biological function of stigmasterol. We report here the identification and characterization of ZmCYP710A8, the sole maize C-22 sterol desaturase involved in stigmasterol biosynthesis and the identification of a stigmasterol-free Zmcyp710a8 mutant. ZmCYP710A8 mRNA expression pattern correlated with transcripts for several sterol biosynthesis genes and loss of stigmasterol impacted sterol composition. Exogenous stigmasterol also had a stimulatory effect on mRNA for ZmHMGR and ZmSMT2. This demonstrates the potential of Zmcyp710a8 in understanding the role of stigmasterol in modulating sterol biosynthesis and global cellular metabolism. Several amino acids accumulate in the Zmcyp710a8 mutant, offering opportunity for genetic enhancement of nutritional quality of maize. Other cellular metabolites in roots and shoots of maize and Arabidopsis were also impacted by genetic modification of stigmasterol content. Yet lack of obvious developmental defects in Zmcyp710a8 suggest that stigmasterol might not be essential for plant growth under normal conditions. Nonetheless, the Zmcyp710a8 mutant reported here is of great utility to advance our understanding of the additional roles of stigmasterol in plant metabolism. A number of biological and agronomic questions can be interrogated using this tool such as gene expression studies, spatio-temporal localization of sterols, cellular metabolism, pathway regulation, physiological studies, and crop improvement.

scholarly journals Membrane Sterol Composition in Arabidopsis thaliana Affects Root Elongation via Auxin Biosynthesis

2021 ◽  
Vol 22 (1) ◽  
pp. 437
Author(s):  
Meng Wang ◽  
Panpan Li ◽  
Yao Ma ◽  
Xiang Nie ◽  
Markus Grebe ◽  
...  
Keyword(s):  
Root Elongation ◽  
Auxin Transport ◽  
Sterol Composition ◽  
Polar Auxin Transport ◽  
Sterol Biosynthesis ◽  
Auxin Biosynthesis ◽  
Root Tip ◽  
Auxin Signaling ◽  
Auxin Response ◽  
Short Root

Plant membrane sterol composition has been reported to affect growth and gravitropism via polar auxin transport and auxin signaling. However, as to whether sterols influence auxin biosynthesis has received little attention. Here, by using the sterol biosynthesis mutant cyclopropylsterol isomerase1-1 (cpi1-1) and sterol application, we reveal that cycloeucalenol, a CPI1 substrate, and sitosterol, an end-product of sterol biosynthesis, antagonistically affect auxin biosynthesis. The short root phenotype of cpi1-1 was associated with a markedly enhanced auxin response in the root tip. Both were neither suppressed by mutations in polar auxin transport (PAT) proteins nor by treatment with a PAT inhibitor and responded to an auxin signaling inhibitor. However, expression of several auxin biosynthesis genes TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1 (TAA1) was upregulated in cpi1-1. Functionally, TAA1 mutation reduced the auxin response in cpi1-1 and partially rescued its short root phenotype. In support of this genetic evidence, application of cycloeucalenol upregulated expression of the auxin responsive reporter DR5:GUS (β-glucuronidase) and of several auxin biosynthesis genes, while sitosterol repressed their expression. Hence, our combined genetic, pharmacological, and sterol application studies reveal a hitherto unexplored sterol-dependent modulation of auxin biosynthesis during Arabidopsis root elongation.

scholarly journals Sterol biosynthesis de nova via cycloartenol by the soil amoeba Acanthamoeba polyphaga

1985 ◽  
Vol 231 (3) ◽  
pp. 609-615 ◽  
Author(s):  
D Raederstorff ◽  
M Rohmer
Keyword(s):  
Culture Medium ◽  
De Novo ◽  
Sterol Composition ◽  
Sterol Biosynthesis ◽  
Acanthamoeba Polyphaga ◽  
Biochemical Processes ◽  
Unicellular Algae ◽  
Unknown Structure ◽  
Soil Amoeba

The soil amoeba Acanthamoeba polyphaga is capable of synthesizing its sterols de novo from acetate. The major sterols are ergosterol and poriferasta-5,7,22-trienol. Furthermore C28 and C29 sterols of still unknown structure with an aromatic B-ring are also synthesized by the amoeba. The first cyclic sterol precursor is cycloartenol, which is the sterol precursor in all photosynthetic phyla. No trace of lanosterol, which is the sterol precursor in animals and fungi, could be detected. These results show that at least some of the biochemical processes of Acanthamoeba polyphaga might be phylogenetically related to those of unicellular algae. Addition of exogenous sterols to the culture medium does not influence the sterol biosynthesis and the sterol composition of the cells.

scholarly journals Interaction of Local Anesthetics with Biomembranes Consisting of Phospholipids and Cholesterol: Mechanistic and Clinical Implications for Anesthetic and Cardiotoxic Effects

2013 ◽  
Vol 2013 ◽  
pp. 1-18 ◽  
Author(s):  
Hironori Tsuchiya ◽  
Maki Mizogami
Keyword(s):  
Lipid Bilayers ◽  
Local Anesthetics ◽  
Cell Membranes ◽  
Membrane Lipids ◽  
Transmembrane Proteins ◽  
Membrane Lipid ◽  
Direct Inhibition ◽  
Drug Molecules ◽  
Site Of Action ◽  
Lipid Barriers

Despite a long history in medical and dental application, the molecular mechanism and precise site of action are still arguable for local anesthetics. Their effects are considered to be induced by acting on functional proteins, on membrane lipids, or on both. Local anesthetics primarily interact with sodium channels embedded in cell membranes to reduce the excitability of nerve cells and cardiomyocytes or produce a malfunction of the cardiovascular system. However, the membrane protein-interacting theory cannot explain all of the pharmacological and toxicological features of local anesthetics. The administered drug molecules must diffuse through the lipid barriers of nerve sheaths and penetrate into or across the lipid bilayers of cell membranes to reach the acting site on transmembrane proteins. Amphiphilic local anesthetics interact hydrophobically and electrostatically with lipid bilayers and modify their physicochemical property, with the direct inhibition of membrane functions, and with the resultant alteration of the membrane lipid environments surrounding transmembrane proteins and the subsequent protein conformational change, leading to the inhibition of channel functions. We review recent studies on the interaction of local anesthetics with biomembranes consisting of phospholipids and cholesterol. Understanding the membrane interactivity of local anesthetics would provide novel insights into their anesthetic and cardiotoxic effects.

scholarly journals Asymmetric phospholipids impart novel biophysical properties to lipid bilayers allowing environmental adaptation

2020 ◽  
Author(s):  
Paul Smith ◽  
Dylan M. Owen ◽  
Christian D. Lorenz ◽  
Maria Makarova
Keyword(s):  
Lipid Bilayers ◽  
Mammalian Cells ◽  
Yeast Species ◽  
Membrane Lipid ◽  
Head Group ◽  
Biophysical Properties ◽  
Biophysical Parameters ◽  
Unsaturated Lipids ◽  
Chain Acyl ◽  
Dynamics Simulations

AbstractPhospholipids are a diverse group of biomolecules consisting of a hydrophilic head group and two hydrophobic acyl tails. The nature of the head and length and saturation of the acyl tails are important for defining the biophysical properties of lipid bilayers. It has recently been shown that the membranes of certain yeast species contain high levels of unusual asymmetric phospholipids, consisting of one long and one medium chain acyl moiety – a configuration not common in mammalian cells or other well studied model yeast species. This raises the possibility that structurally asymmetric phospholipids impart novel biophysical properties to the yeast membranes. Here, we use atomistic molecular dynamics simulations (MD) and environmentally-sensitive fluorescent membrane probes to characterize key biophysical parameters of membranes formed from asymmetric lipids for the first time. Interestingly, we show that saturated, but asymmetric phospholipids maintain membrane lipid order across a wider range of temperatures and do not require acyl tail unsaturation or sterols to maintain their properties. This may allow cells to maintain membrane fluidity even in environments which lack the oxygen required for the synthesis of unsaturated lipids and sterols.

Radiation-induced mutations in genetic enhancement and development of new crop varieties in black gram (Vigna mungo (L.) Hepper).

2021 ◽  
pp. 303-311
Author(s):  
Souframanien Jegadeesan ◽  
Kandali Sreenivasulu Reddy
Keyword(s):  
Genetic Variability ◽  
Crop Improvement ◽  
Vigna Mungo ◽  
Genetic Enhancement ◽  
Black Gram ◽  
Induced Mutations ◽  
Cross Breeding ◽  
Environmentally Sustainable ◽  
Large Seed ◽  
High Yielding Varieties

Abstract Black gram (Vigna mungo (L.) Hepper), popularly known as urdbean or mash or black gram, is a grain legume rich in protein (25-28%), widely cultivated in the Indian subcontinent and to a lesser extent in Thailand, Australia and other Asian and South Pacific countries. Genetic improvement in this crop is hindered due to the narrow genetic base. As genetic variability is a prerequisite for any crop improvement programme, induced mutations provide an important source for generating variability. Radiation (gamma, X-rays and neutron) induced mutants were identified for various morphological and biochemical traits, creating a pool of genetic variability. These mutants were used in a cross-breeding programme to develop high-yielding, disease-resistant varieties in black gram. The effective blend of mutation and recombination breeding at the Bhabha Atomic Research Centre has resulted in the release of five black gram varieties (TAU-1, TAU-2, TPU-4, TU94-2 and TU-40) by incorporating desirable traits like large seed, wider adaptability, resistance to disease and improved quality. These varieties have been developed from mutants directly or by using them in cross-breeding programmes. For example, a black gram variety, N0.55, was irradiated with gamma-rays and electron beams to obtain a large number of mutants. The large-seed mutants, UM-196 and UM-201, were used in cross-breeding with the elite cultivar T-9 for developing the high-yielding varieties TAU-1, TAU-2, TPU-4, TU94-2 and TU-40. TAU-1 has become the most popular variety in Maharashtra state, occupying the maximum area under black gram cultivation. Induced mutations will continue to play an increasing role in generating genetic variability for various traits as a major component of environmentally sustainable agriculture.

scholarly journals The Effect of Lidocaine · HCl on the Fluidity of Native and Model Membrane Lipid Bilayers

2012 ◽  
Vol 16 (6) ◽  
pp. 413 ◽  
Author(s):  
Jun-Seop Park ◽  
Tae-Sang Jung ◽  
Yang-Ho Noh ◽  
Woo-Sung Kim ◽  
Won-Ick Park ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Membrane Lipid ◽  
Model Membrane ◽  
Lidocaine Hcl

scholarly journals Defects in Structural Integrity of Ergosterol and the Cdc50p-Drs2p Putative Phospholipid Translocase Cause Accumulation of Endocytic Membranes, onto Which Actin Patches Are Assembled in Yeast

2005 ◽  
Vol 16 (12) ◽  
pp. 5592-5609 ◽  
Author(s):  
Takuma Kishimoto ◽  
Takaharu Yamamoto ◽  
Kazuma Tanaka
Keyword(s):  
Lipid Bilayers ◽  
Cell Polarity ◽  
Structural Integrity ◽  
Membrane Lipid ◽  
Actin Organization ◽  
Ergosterol Synthesis ◽  
Simultaneous Loss ◽  
Synthetically Lethal ◽  
Golgi Network ◽  
And Control

Specific changes in membrane lipid composition are implicated in actin cytoskeletal organization, vesicle formation, and control of cell polarity. Cdc50p, a membrane protein in the endosomal/trans-Golgi network compartments, is a noncatalytic subunit of Drs2p, which is implicated in translocation of phospholipids across lipid bilayers. We found that the cdc50Δ mutation is synthetically lethal with mutations affecting the late steps of ergosterol synthesis (erg2 to erg6). Defects in cell polarity and actin organization were observed in the cdc50Δ erg3Δ mutant. In particular, actin patches, which are normally found at cortical sites, were assembled intracellularly along with their assembly factors, including Las17p, Abp1p, and Sla2p. The exocytic SNARE Snc1p, which is recycled by an endocytic route, was also intracellularly accumulated, and inhibition of endocytic internalization suppressed the cytoplasmic accumulation of both Las17p and Snc1p. Simultaneous loss of both phospholipid asymmetry and sterol structural integrity could lead to accumulation of endocytic intermediates capable of initiating assembly of actin patches in the cytoplasm.

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