Descrizione del progetto
Logistica dei cloroplasti e ruolo dei complessi di importazione delle proteine
Le cellule sono fabbriche complesse con singoli organelli legati alla membrana che contribuiscono a categorizzare i lavori e le risorse necessarie per svolgerli, migliorando l’efficienza. La logistica cellulare può diventare piuttosto complicata dato che le proteine sono codificate nel nucleo, assemblate sui ribosomi e trasportate al loro posto di lavoro in tutta la cellula. I cloroplasti sono gli organelli fotosintetici nelle cellule vegetali e dispongono di macchine molecolari specializzate che traslocano le proteine attraverso il loro involucro di membrana a doppia parete. Il cosiddetto apparato di traslocazione nella membrana cloroplastica dell’involucro esterno ha almeno due configurazioni principali corrispondenti al carico pre-proteico importato. Il progetto TOC-maker, finanziato dall’UE, sta studiando i dettagli del processo di assemblaggio e l’organizzazione strutturale finale dei complessi di trasloconi TOC.
Obiettivo
Plants convert solar energy into chemical energy by the process called photosynthesis in a specialized compartment of the cell known as chloroplasts. Chloroplasts are majorly enriched with nucleus-encoded proteins and to import them, chloroplast outer and inner envelope membranes are equipped with apparatus called the TOC and TIC translocons, respectively. For the TOC apparatus, there are two major configurations, TOC-P and TOC-H, reported so far, which import highly abundant, Photosynthetic and Housekeeping pre-proteins, respectively. TOC-P and TOC-H are multiprotein complexes which must be specifically assembled for proper development and homeostasis of the chloroplast. Due to the dynamic nature of the translocons, component synthesis and assembly must be rapid and tightly coupled, making the process difficult to investigate. Thus, understanding the mechanisms of the assembly process is both challenging and exciting. Biogenesis of TOC complexes is rapidly enhanced during chloroplast development or de-etiolation, and I will exploit this process to investigate the assembly of different TOC configurations, using the model plant Arabidopsis thaliana. For this purpose, transgenic plants expressing epitope-tagged TOC components and cells expressing nascent polypeptides of TOC components with stalled ribosomes will be generated. Proteins transiently interacting with new TOC components, which are predicted to assist integration and assembly of the TOC complex, will be studied by using affinity purification, pulse-chase experiments, and other biochemical techniques, and thus a sequence of assembly events will be elucidated. Although the molecular composition of the TOC protein import machinery has been well studied, the detailed structural organization of TOC complexes has not yet been elucidated. I will address this knowledge gap by analysing affinity-purified TOC complexes from mature chloroplasts at high resolution by cryo-electron microscopy.
Campo scientifico
- engineering and technologyenvironmental engineeringenergy and fuelsrenewable energysolar energy
- natural sciencesbiological sciencesbiochemistrybiomoleculesproteins
- natural sciencesphysical sciencesopticsmicroscopy
- medical and health sciencesbasic medicinephysiologyhomeostasis
- natural sciencesbiological sciencesbotany
Parole chiave
Programma(i)
Argomento(i)
Meccanismo di finanziamento
MSCA-IF - Marie Skłodowska-Curie Individual Fellowships (IF)Coordinatore
OX1 2JD Oxford
Regno Unito