Biology subjects

D'Hulst, C.

Publications and source records attributed to D'Hulst, C..

4 recordsLinked to original sources

bioRxiv2025

LIKE EARLY STARVATION is involved in the regulation of starch initiation in potato (Solanum tuberosum cv. Desiree) tubers

Starch initiation has been intensively investigated. In tubers of Solanum tuberosum, it is controlled by a heteromultimeric isoamylase complex composed of ISA1 and ISA2. Moreover, two non-catalytic starch binding proteins (i.e., ESV1 and LESV) regulate leaf starch metabolism in Arabidopsis. Both proteins interact with starch glucans through a C-terminal antiparallel {beta}-sheet domain and differ by the presence of a 115 amino acid N-terminal overhang in LESV. Here we report the CRIPSR/Cas9 inactivation of LESV or ESV1 in potato and the characterization of the respective tuber starches. Starch from esv1 mutants was unaffected whereas granule diameter was severely reduced in tubers of lesv plants. This was negatively correlated to the number of granules, coherent with an altered starch initiation phenotype. Strikingly, scanning electron microscopy of purified starches revealed that lesv plants phenocopy isa1 and isa2 antisense lines described 20 years ago. A physical interaction between LESV and ISA1 was previously demonstrated in rice. Here, we confirmed this interaction in potato using yeast two-hybrid assays, providing molecular evidence for their functional association in potato. This interaction supports the hypothesis that LESV acts in concert with the ISA1/ISA2 complex, likely regulating the early steps of glucan organization required for proper starch granule formation.

plant biology↗

bioRxiv2023

Structural basis of the interaction between ESV1 and LESV from Arabidopsis thaliana with starch glucans.

Starch is the major energy storage compound in plants. Whether it is transient or stored, it is accumulated in the form of insoluble, semi-crystalline granules. The structure of these granules is related to the structure of the main component: amylopectin. Amylopectin consists of linear polymers of glucose units linked by -1,4 bonds, forming double helices that combine to form the semi-crystalline lamellae of the granules, and -1,6 branching points that form the amorphous lamellae. This particular structure of amylopectin is linked to the action of isoamylases, which cut the excess of branching points and allow the granules to be structured. For a long time, it was thought that the action of these enzymes was responsible for the structuring of starch granules. Recently, two new proteins, LESV and ESV1, have been characterized and are involved in the phase transition of amylopectin (LESV) or in the maintenance of the granule structure (ESV1). These proteins share a tryptophan-rich domain folded into an antiparallel {beta}-sheet that is particularly well suited to bind amylopectin double helices. In this paper we present the structural study of these interactions using integrative structural biology approaches and show that LESV, in contrast to ESV1 can intervenes during amylopectin biosynthesis.

biophysics↗

bioRxiv2022

Commonality of Odorant Receptor Choice Mechanism Revealed by Analysis of a Highly Represented Odorant Receptor Transgene

In the mouse, more than 1,100 odorant receptors (ORs) are expressed in a monogenic and monoallelic fashion, referred to as singular gene expression. Using a 21bp singular-choice enhancer (x21), we radically increase representation of olfactory sensory neurons (OSNs) choosing a 5x21 enhanced OR transgene, but not overexpression of its mRNA on a per cell basis. RNA-sequencing and differential expression analysis identified 425 differentially expressed genes (DEGs). ORs make up 86% of all DEGs, of which 325 have decreased representation and 40 have increased representation. Underrepresented ORs include Class I, Class II and TAAR genes and within each of their respective olfactory bulb domains: DI, DII, and DIII (TAAR) we committedly observe multiple homogeneous glomeruli with an OR1A1-identity. The underrepresentation of endogenous, class-specific ORs across evolutionarily distinct cell types in favor of the expression of the 5x21-OR1A1 transgene argues that a common mechanism of singular gene choice is present for all OR-expressing OSNs.

neuroscience↗

bioRxiv2021

A Genetic Platform for Functionally Profiling Odorant Receptors Ex Vivo Using Olfactory Cilia.

The molecular basis for odor perception in humans remains an enigma as odorant receptors (ORs) are notoriously difficult to study outside of their native environment. Efforts toward OR expression and functional profiling have been met with limited success due to poor efficiency of in vitro cell surface expression. Olfactory cilia are known to contain all components of the olfactory signal transduction machinery and can be placed into an ex vivo well-plate assay to rapidly measure robust, reproducible odor-specific responses. We now describe the isolation of cilia from mouse nose bioreactors for two human ORs, OR1A1 and OR5AN1, and reveal 10-100 fold more sensitivity compared to previously reported assays. A single animal can produce up to 4,000 384-well assay wells, and isolated olfactory cilia can be stored frozen and thus preserved. This pipeline offers a sensitive, highly scalable ex vivo odor screening platform that opens the door for decoding human olfaction. One Sentence Summaryolfactory-cilia based odor screening platform.

neuroscience↗