Strictosidine activation in Apocynaceae: towards a 'nuclear time bomb'?

Guirimand, Grégory; Courdavault, Vincent; Lanoue, Arnaud; Mahroug, Samira; Guihur, Anthony; Blanc, Nathalie; Giglioli-Guivarc'h, Nathalie; St-Pierre, Benoit; Burlat, Vincent
January 2010
BMC Plant Biology;2010, Vol. 10, p182
Academic Journal
Background: The first two enzymatic steps of monoterpene indole alkaloid (MIA) biosynthetic pathway are catalysed by strictosidine synthase (STR) that condensates tryptamine and secologanin to form strictosidine and by strictosidine b-D-glucosidase (SGD) that subsequently hydrolyses the glucose moiety of strictosidine. The resulting unstable aglycon is rapidly converted into a highly reactive dialdehyde, from which more than 2,000 MIAs are derived. Many studies were conducted to elucidate the biosynthesis and regulation of pharmacologically valuable MIAs such as vinblastine and vincristine in Catharanthus roseus or ajmaline in Rauvolfia serpentina. However, very few reports focused on the MIA physiological functions. Results: In this study we showed that a strictosidine pool existed in planta and that the strictosidine deglucosylation product(s) was (were) specifically responsible for in vitro protein cross-linking and precipitation suggesting a potential role for strictosidine activation in plant defence. The spatial feasibility of such an activation process was evaluated in planta. On the one hand, in situ hybridisation studies showed that CrSTR and CrSGD were coexpressed in the epidermal first barrier of C. roseus aerial organs. However, a combination of GFP-imaging, bimolecular fluorescence complementation and electromobility shift-zymogram experiments revealed that STR from both C. roseus and R. serpentina were localised to the vacuole whereas SGD from both species were shown to accumulate as highly stable supramolecular aggregates within the nucleus. Deletion and fusion studies allowed us to identify and to demonstrate the functionality of CrSTR and CrSGD targeting sequences. Conclusions: A spatial model was drawn to explain the role of the subcellular sequestration of STR and SGD to control the MIA metabolic flux under normal physiological conditions. The model also illustrates the possible mechanism of massive activation of the strictosidine vacuolar pool upon enzyme-substrate reunion occurring during potential herbivore feeding constituting a so-called "nuclear time bomb" in reference to the "mustard oil bomb" commonly used to describe the myrosinase-glucosinolate defence system in Brassicaceae.


Related Articles

  • Encapsulation of bilayer vesicles by self-assembly. Walker, Scott A.; Kennedy, Michael T. // Nature;5/1/1997, Vol. 387 Issue 6628, p61 

    Demonstrates that molecular-recognition processes mediated by lipophilic receptors and substrates can be used to produce a multicompartmental aggregate of tethered vesicles encapsulated within a large bilayer vesicle. The naming of the encapsulated aggregates as vesosomes; The use of vesosomes...

  • Whole Genome Characterization of the Mechanisms of Daptomycin Resistance in Clinical and Laboratory Derived Isolates of Staphylococcus aureus. Peleg, Anton Y.; Miyakis, Spiros; Ward, Doyle V.; Earl, Ashlee M.; Rubio, Aileen; Cameron, David R.; Pillai, Satish; Moellering, Jr., Robert C.; Eliopoulos, George M. // PLoS ONE;Jan2012, Vol. 7 Issue 1, p1 

    Background: Daptomycin remains one of our last-line anti-staphylococcal agents. This study aims to characterize the genetic evolution to daptomycin resistance in S. aureus. Methods: Whole genome sequencing was performed on a unique collection of isogenic, clinical (21 strains) and laboratory (12...

  • Heteromeric and Homomeric Geranyl Diphosphate Synthases from Catharanthus roseus and Their Role in Monoterpene Indole Alkaloid Biosynthesis. Rai, Avanish; Smita, Shachi S.; Singh, Anup Kumar; Shanker, Karuna; Nagegowda, Dinesh A. // Molecular Plant (Oxford University Press / USA);Sep2013, Vol. 6 Issue 5, p1531 

    This work suggests that, in Catharanthus roseus, the inactive small subunit of heteromeric GPP synthase (GPPS) interacts with bifunctional G(G)PPS and redirects the metabolic flux, thus acting as primary regulator of monoterpene indole alkaloid biosynthesis, whereas homomeric GPPS could be...

  • Ultrasound-Mediated Therapies Using Receptor-Targeted Nanodroplets. Schumann, P.; LaBell, R.; Penrose, K.; Kerschen, A.; Unger, E.; Matsunaga, T.; Zutshi, R. // AIP Conference Proceedings;2006, Vol. 829 Issue 1, p525 

    Angiogenic vessels at tumor sites are leaky and allow particles less than 400 nm to pass through. We have developed targeted nanodroplets that are less than 400 nm in size and are capable of encapsulating drug molecules which can be released at the tumor site upon insonation. These nanodroplets...

  • Comparison of cholesterol and its direct precursors along the biosynthetic pathway: Effects of cholesterol, desmosterol and 7-dehydrocholesterol on saturated and unsaturated lipid bilayers. Róg, Tomasz; Vattulainen, Ilpo; Jansen, Maurice; Ikonen, Elina; Karttunen, Mikko // Journal of Chemical Physics;10/21/2008, Vol. 129 Issue 15, p154508 

    Despite extensive studies, the remarkable structure-function relationship of cholesterol in cellular membranes has remained rather elusive. This is exemplified by the fact that the membrane properties of cholesterol are distinctly different from those of many other sterols. Here we elucidate...

  • The early evolution of lipid membranes and the three domains of life. Lombard, Jonathan; López-García, Purificación; Moreira, David // Nature Reviews Microbiology;Jul2012, Vol. 10 Issue 7, p507 

    All cell membranes are composed of glycerol phosphate phospholipids, and this commonality argues for the presence of such phospholipids in the last common ancestor, or cenancestor. However, phospholipid biosynthesis is very different between bacteria and archaea, leading to the suggestion that...

  • A theoretical model for the association of amphiphilic transmembrane peptides in lipid bilayers. Sperotto, Maria Maddalena // European Biophysics Journal;1997, Vol. 26 Issue 5, p405 

    Abstract A theoretical model is proposed for the association of trans-bilayer peptides in lipid bilayers. The model is based on a lattice model for the pure lipid bilayer, which accounts accurately for the most important conformational states of the lipids and their mutual interactions and...

  • Role of Electrostatic and Hydrophobic Interactions in Ca2+;-Dependent Phospholipid Binding by the C[sub2]A-Domain From Synaptotagmin 1. Gerber, Stefan H.; Rizo, Josep; Südhof, Thomas C. // Diabetes;Feb2002 Supplement, Vol. 51, pS12 

    Most C[sub 2]-domains bind to phospholipid bilayers as a function of Ca[sup 2+]. Although phospholipid binding is central for the normal functions of C[sub 2]-domain proteins, the precise mechanism of phospholipid binding is unclear. One of the key questions is whether phospholipid binding by...

  • Fluctuations caught in the act. Nielsen, Lars K.; Bjornholm, Thomas // Nature;3/23/2000, Vol. 404 Issue 6776, p352 

    Shows that critical fluctuations in the domains in a lipid monolayer can be captured and measured by immobilizing the monolayer on a solid support and visualizing the pattern using atomic-force microscopy. Nanometer-scale domain organization in the lipid-bilayer component of biological...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics