Medium-Chain Polyprenols Influence Chloroplast Membrane Dynamics in Solanum lycopersicum

Abstract

The widespread occurrence of polyprenols throughout the plant kingdom is well documented, yet their functional role is poorly understood. These lipophilic compounds are known to be assembled from isoprenoid precursors by a class of enzymes designated as cis-prenyltransferases (CPTs), which are encoded by small CPT gene families in plants. In this study, we report that RNA interference (RNAi)-mediated knockdown of one member of the tomato CPT family (SlCPT5) reduced polyprenols in leaves by about 70%. Assays with recombinant SlCPT5 produced in Escherichia coli determined that the enzyme synthesizes polyprenols of approximately 50-55 carbons (Pren-10, Pren-11) in length and accommodates a variety of trans-prenyldiphosphate precursors as substrates. Introduction of SlCPT5 into the polyprenol-deficient yeast Δrer2 mutant resulted in the accumulation of Pren-11 in yeast cells, restored proper protein N-glycosylation and rescued the temperature-sensitive growth phenotype that is associated with its polyprenol deficiency. Subcellular fractionation studies together with in vivo localization of SlCPT5 fluorescent protein fusions demonstrated that SlCPT5 resides in the chloroplast stroma and that its enzymatic products accumulate in both thylakoid and envelope membranes. Transmission electron microscopy images of polyprenol-deficient leaves revealed alterations in chloroplast ultrastructure, and anisotropy measurements revealed a more disordered state of their envelope membranes. In polyprenol-deficient leaves, CO2 assimilation was hindered and their thylakoid membranes exhibited lower phase transition temperatures and calorimetric enthalpies, which coincided with a decreased photosynthetic electron transport rate. Taken together, these results uncover a role for polyprenols in governing chloroplast membrane dynamics.

Nerylneryl diphosphate is the precursor of serrulatane, viscidane and cembrane-type diterpenoids in Eremophila species

“…For the ER localised candidates, one cluster was positioned within a clade containing CPTs involved in rubber biosynthesis [46,48,61] and the second cluster was associated with a clade containing long-chain polyprenyl diphosphate synthases that participate in dolichol biosynthesis [48,62]. Of those Eremophila CPTs predicted to have plastid transit peptides, one group segregated with CPTs of medium and long-chain synthesising enzymes involved in plastid localised polyprenol biosynthesis [49,63] while the other and h Mass spectra of major TPS products. e, g, i and j Chemical structures of (3Z,7Z,11Z)-cembratrien-15-ol (6), 5-hydroxyviscidane (8), 8,9-dihydroserrulat-14-ene (11) and serrulat-14-ene (12) group clustered with short-chain synthesising enzymes that are involved in mono-, sesqui-and diterpene biosynthesis in Solanum spp.…”

In Search for the Membrane Regulators of Archaea

“…In contrast, shorter chain polyprenols, such as C55 and C95, promote hydrophobic interactions with the lipid acyl chains [95], and thus reduce water permeability, especially in polyprenyl-phosphate based membranes [99]. In plants, these medium-chain polyprenols reduce lipid acyl chain motion, and thus membrane fluidity, in the protein-dense thylakoid membranes [106,107]. Although polar headgroups appear to greatly impact the membrane location of polyprenols, no study has been performed to estimate their impact on membrane parameters.…”

Cultivation at high osmotic pressure confers ubiquinone 8–independent protection of respiration onEscherichia coli

“…Q8 is a redox-active lipid that plays three well-established physiological roles in E. coli: it mediates electron transfer from dehydrogenases to terminal oxidases within the respiratory chain, its reduced form (ubiquinol 8) mitigates oxidative stress by serving as an antioxidant, and it is implicated in the regulation of gene expression (12). Other ubiquinones and isoprenoid lipids influence physical properties of phospholipid membranes (13)(14)(15)(16)(17)(18). However, in most cases, the physiological significance of these effects is unclear.…”