Biology subjects

Swiezewska, E.

Publications and source records attributed to Swiezewska, E..

4 recordsLinked to original sources

bioRxiv2024

The Arabidopsis thaliana TRAPPIII subunit AtTRAPPC8/AtTRS85 is involved in ER functioning and autophagy

TRAPP (transport protein particle) tethering complexes are known for their function as Rab-GTPase exchange factors (GEFs). Two versions of the complex are considered functionally separate: TRAPPII, an activator of GTPases of the Rab11 family (RabA in plants) which functions in post-Golgi sorting, and TRAPPIII, activating the Rab1 family (RabD in plants) which regulates ER-to-Golgi trafficking and autophagy. In Arabidopsis thaliana, the TRAPPIII complex has been identified and its subunit composition established, but little is known about its functions. Here, we found that binary subunit interactions of the plant TRAPPIII complex are analogous to those of metazoan TRAPPIII, with the two large subunits TRAPPC8 and -C11 linking the TRAPP core and the small C12-C13 dimer. To gain insight into the functions of TRAPPIII in plants, we characterized two A. thaliana trappc8 mutants. The mutants display abnormalities in plant morphology, in particular in flower and seed development. They also have autophagic defects, constitutive ER stress response, and elevated levels of the ER lipid dolichol - an indispensable cofactor of protein glycosylation. These results show that plant TRAPPC8 is involved in multiple trafficking steps in the cells and they suggest a novel link between ER membrane turnover and dolichol levels. HIGHLIGHTArabidopsis thaliana TRAPPC8 is necessary for correct functioning of the ER, in particular for its lipid homeostasis. Dysruption of TRAPPC8 leads to defects in secretion, autophagosome formation, and plant development.

plant biology↗

bioRxiv2021

HSFA1 proteins mediate heat-induced accumulation of CPT7-derived polyprenols affecting thylakoid organization

Polyprenols are ubiquitous isoprenoid compounds that accumulate in large quantities in plant photosynthetic tissues. While our knowledge of polyprenol biochemistry is constantly expanding, the regulation of their biosynthesis as well as the molecular basis of their cellular action are still poorly understood. In Arabidopsis, the polyprenols Pren-9, -10 and -11, synthesized by cis-prenyltransferase 7 (CPT7), are localized in plastidial membranes and affect the photosynthetic performance of chloroplasts. In this report we present evidence that plastidial polyprenols are among the major constituents of thylakoid membranes. Disturbances in polyprenol level, caused by alterations in CPT7 expression, change chloroplast ultrastructure, affect aggregation of LHCII complexes and modulate non-photochemical quenching (NPQ). Moreover, we show that Arabidopsis responds to high temperature by upregulating expression of CPT7 and increasing the accumulation of CPT7-derived polyprenols. These heat-induced changes in polyprenol biosynthesis are mediated by Heat Shock Transcription Factors of the HSFA1 family, the master regulators of heat stress response. Collectively, results presented in this report bring us closer to understanding the mechanisms by which polyprenols affect plant physiology and provide an additional link between chloroplast biology and plant responses to changing environmental conditions. One sentence summaryHeat Shock Transcription Factors induce biosynthesis of polyprenols - isoprenoid compounds that affect the organization and function of chloroplasts.

plant biology↗

bioRxiv2020

GWAS analysis combined with QTL mapping identify CPT3 and ABH as genes underlying dolichol accumulation in Arabidopsis

Dolichols (Dols), ubiquitous components of living organisms, are indispensable for cell survival. In plants, as well as other eukaryotes, Dols are crucial for posttranslational protein glycosylation, aberration of which leads to fatal metabolic disorders in humans. Until now, the regulatory mechanisms underlying Dol accumulation remain elusive. In this report, we have analyzed the natural variation of the accumulation of Dols and six other isoprenoids between 120 Arabidopsis thaliana accessions. Subsequently, by combining QTL and GWAS approaches, we have identified several candidate genes involved in the accumulation of Dols, polyprenols, plastoquinone, and phytosterols. The role of two genes implicated in the accumulation of major Dols in Arabidopsis - the AT2G17570 gene encoding a long searched for cis-prenyltransferase (CPT3) and the AT1G52460 gene encoding an alpha-beta hydrolase (ABH) - is experimentally confirmed. These data will help to generate Dol-enriched plants which might serve as a remedy for Dol-deficiency in humans.

genomics↗

bioRxiv2019

Metabolomic profiling reveals developmentally regulated biosynthesis of polyprenols and dolichols in the malaria parasite

The cis-polyisoprenoid lipids namely polyprenols, dolichols and their derivatives are linear polymers of several isoprene units. In eukaryotes, polyprenols and dolichols are synthesized as a mixture of four or more homologues of different length with one or two predominant species with sizes varying among organisms. Polyprenols have been hardly detectable in eukaryotic cells under normal conditions with the exception of plants and sporulating yeast. Our metabolomics studies revealed that cis-polyisoprenoids are more prevalent and diverse in the parasite Plasmodium falciparum than previously postulated as we uncovered active de novo biosynthesis and substantial levels of accumulation of polyprenols and dolichols of 15 to 19 isoprene units. A distinctive polyprenol and dolichol profile both within the intraerythrocytic asexual cycle and between asexual and gametocyte stages was also observed suggesting that cis-polyisoprenoid biosynthesis changes throughout parasites development. In addition, we confirmed the presence of an active cis-prenyltransferase (PfCPT) and that dolichol biosynthesis occurs via reduction of the polyprenol to dolichol by an active polyprenol reductase (PfPPRD) in the malaria parasite. Isotopic labeling and metabolomic analyses of a conditional mutant of PfCPT or PfPPRD suggest that polyprenols may be able to substitute dolichols in their biological functions when dolichol synthesis is impaired in Plasmodium.

biochemistry↗