skip to main content

Attention:

The NSF Public Access Repository (NSF-PAR) system and access will be unavailable from 11:00 PM ET on Friday, April 12 until 2:00 AM ET on Saturday, April 13 due to maintenance. We apologize for the inconvenience.


Title: Engineering ‘designer’ glycomodules for boosting recombinant protein secretion in tobacco hairy root culture and studying hydroxyproline‐ O ‐glycosylation process in plants
Summary

The key technical bottleneck for exploiting plant hairy root cultures as a robust bioproduction platform for therapeutic proteins has been low protein productivity, particularly low secreted protein yields. To address this, we engineered novel hydroxyproline (Hyp)‐O‐glycosylated peptides (HypGPs) into tobacco hairy roots to boost the extracellular secretion of fused proteins and to elucidate Hyp‐O‐glycosylation process of plant cell wall Hyp‐rich glycoproteins. HypGPs representing two major types of cell wall glycoproteins were examined: an extensin module consisting of 18 tandem repeats of ‘Ser‐Hyp‐Hyp‐Hyp‐Hyp’ motif or (SP4)18and an arabinogalactan protein module consisting of 32 tandem repeats of ‘Ser‐Hyp’ motif or (SP)32. Each module was expressed in tobacco hairy roots as a fusion to the enhanced green fluorescence protein (EGFP). Hairy root cultures engineered with a HypGPmodule secreted up to 56‐fold greater levels ofEGFP, compared with anEGFPcontrol lacking any HypGPmodule, supporting the function of HypGPmodules as a molecular carrier in promoting efficient transport of fused proteins into the culture media. The engineered (SP4)18and (SP)32modules underwent Hyp‐O‐glycosylation with arabino‐oligosaccharides and arabinogalactan polysaccharides, respectively, which were essential in facilitating secretion of the fusedEGFPprotein. Distinct non‐Hyp‐O‐glycosylated (SP4)18EGFPand (SP)32EGFPintermediates were consistently accumulated within the root tissues, indicating a rate‐limiting trafficking and/or glycosylation of the engineered HypGPmodules. An updated model depicting the intracellular trafficking, Hyp‐O‐glycosylation and extracellular secretion of extensin‐styled (SP4)18module andAGP‐styled (SP)32module is proposed.

 
more » « less
NSF-PAR ID:
10081546
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Plant Biotechnology Journal
Volume:
17
Issue:
6
ISSN:
1467-7644
Page Range / eLocation ID:
p. 1130-1141
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    Reconstructing the chemical and structural characteristics of the plant cell wall represents a promising solution to overcoming lignocellulosic biomass recalcitrance to biochemical deconstruction. This study aims to leverage hydroxyproline (Hyp)‐O‐glycosylation, a process unique to plant cell wall glycoproteins, as an innovative technology for de novo design and engineering in planta of Hyp‐O‐glycosylated biopolymers (HypGP) that facilitate plant cell wall reconstruction. HypGP consisting of 18 tandem repeats of “Ser–Hyp–Hyp–Hyp–Hyp” motif or (SP4)18was designed and engineered into tobacco plants as a fusion peptide with either a reporter protein enhanced green fluorescence protein or the catalytic domain of a thermophilic E1 endoglucanase (E1cd) fromAcidothermus cellulolyticus. The engineered (SP4)18module was extensively Hyp‐O‐glycosylated with arabino‐oligosaccharides, which facilitated the deposition of the fused protein/enzyme in the cell wall matrix and improved the accumulation of the protein/enzyme in planta by 1.5–11‐fold. The enzyme activity of the recombinant E1cd was not affected by the fused (SP4)18module, showing an optimal temperature of 80°C and optimal pH between 5 and 8. The plant biomass engineered with the (SP4)18‐tagged protein/enzyme increased the biomass saccharification efficiency by up to 3.5‐fold without having adverse impact on the plant growth.

     
    more » « less
  2. Summary

    Plants mount coordinated immune responses to defend themselves against pathogens. However, the cellular components required for plant immunity are not fully understood. The jasmonate‐mimicking coronatine (COR) toxin produced byPseudomonas syringaepv.tomato(Pst)DC3000 functions to overcome plant immunity. We previously isolated eight Arabidopsis (scord) mutants that exhibit increased susceptibility to aCOR‐deficient mutant ofPstDC3000. Among them, thescord6mutant exhibits defects both in stomatal closure response and in restricting bacterial multiplication inside the apoplast. However, the identity ofSCORD6remained elusive.

    In this study, we aim to identify theSCORD6gene.

    We identifiedSCORD6via next‐generation sequencing and found it to beMURUS1(MUR1), which is involved in the biosynthesis ofGDPl‐fucose.

    Discovery ofSCORD6asMUR1led to a series of experiments that revealed a multi‐faceted role ofl‐fucose biosynthesis in stomatal and apoplastic defenses as well as in pattern‐triggered immunity and effector‐triggered immunity, including glycosylation of pattern‐recognition receptors. Furthermore, compromised stomatal and/or apoplastic defenses were observed in mutants of several fucosyltransferases with specific substrates (e.g.O‐glycan,N‐glycan or theDELLAtranscriptional repressors). Collectively, these results uncover a novel and broad role ofl‐fucose and protein fucosylation in plant immunity.

     
    more » « less
  3. Summary

    Protein quality control pathways require AAA+ proteases, such as Clp and Lon. Lon protease maintains UmuD, an important component of the error‐prone DNA repair polymerase (Pol V), at very low levels inE.coli. Most members of the phylum Cyanobacteria lack Lon (including the model cyanobacterium,Synechocystissp. PCC6803), so maintenance of UmuD at low levels must employ different proteases. We demonstrate that the first 19 residues from the N‐terminus of UmuD (Sug1‐19) fused to a reporter protein are adequate to trigger complete proteolysis and that mutation of a single leucine residue (L6) to aspartic acid inhibits proteolysis. This process appears to follow the N‐end rule and is mediated by ClpA/P protease and the ClpS adaptor. Additionally, mutations of arginine residues in the Sug1‐19tag suggest that the ClpX/P pathway also plays a role in proteolysis. We propose that there is a dual degron at the N‐terminus of the UmuD protein inSynechocystissp. PCC6803, which is distinct from the degron required for degradation of UmuD inE.coli. The use of two proteolysis pathways to tune levels of UmuD might reflect how a photosynthetic organism responds to multiple environmental stressors.

     
    more » « less
  4. Summary

    The collaborative non‐self‐recognition model for S‐RNase‐based self‐incompatibility predicts that multiple S‐locus F‐box proteins (SLFs) produced by pollen of a givenS‐haplotype collectively mediate ubiquitination and degradation of all non‐self S‐RNases, but not self S‐RNases, in the pollen tube, thereby resulting in cross‐compatible pollination but self‐incompatible pollination. We had previously used pollen extracts containingGFP‐fused S2SLF1 (SLF1 with anS2‐haplotype) ofPetunia inflatafor co‐immunoprecipitation (Co‐IP) and mass spectrometry (MS), and identified PiCUL1‐P (a pollen‐specific Cullin1), PiSSK1 (a pollen‐specific Skp1‐like protein) and PiRBX1 (a conventional Rbx1) as components of theSCFS2–SLF1complex. Using pollen extracts containing PiSSK1:FLAG:GFPfor Co‐IP/MS, we identified two additionalSLFs (SLF4 andSLF13) that were assembled intoSCFSLFcomplexes. As 17SLFgenes (SLF1toSLF17) have been identified inS2andS3pollen, here we examined whether all 17SLFs are assembled into similar complexes and, if so, whether these complexes are unique toSLFs. We modified the previous Co‐IP/MSprocedure, including the addition of style extracts from four differentS‐genotypes to pollen extracts containing PiSSK1:FLAG:GFP, to perform four separate experiments. The results taken together show that all 17SLFs and anSLF‐like protein,SLFLike1 (encoded by anS‐locus‐linked gene), co‐immunoprecipitated with PiSSK1:FLAG:GFP. Moreover, of the 179 other F‐box proteins predicted byS2andS3pollen transcriptomes, only a pair with 94.9% identity and another pair with 99.7% identity co‐immunoprecipitated with PiSSK1:FLAG:GFP. These results suggest thatSCFSLFcomplexes have evolved specifically to function in self‐incompatibility.

     
    more » « less
  5. Summary

    In flowering plants, cell–cell communication plays a key role in reproductive success, as both pollination and fertilization require pathways that regulate interactions between many different cell types. Some of the most critical of these interactions are those between the pollen tube (PT) and the embryo sac, which ensure the delivery of sperm cells required for double fertilization. Synergid cells function to attract thePTthrough secretion of small peptides and inPTreception via membrane‐bound proteins associated with the endomembrane system and the cell surface. While many synergid‐expressed components regulatingPTattraction and reception have been identified, few tools exist to study the localization of membrane‐bound proteins and the components of the endomembrane system in this cell type. In this study, we describe the localization and distribution of seven fluorescent markers that labelled components of the secretory pathway in synergid cells ofArabidopsis thaliana. These markers were used in co‐localization experiments to investigate the subcellular distribution of the twoPTreception componentsLORELEI, aGPI‐anchored surface protein, andNORTIA, aMILDEW RESISTANCE LOCUSO protein, both found within the endomembrane system of the synergid cell. These secretory markers are useful tools for both reproductive and cell biologists, enabling the analysis of membrane‐associated trafficking within a haploid cell actively involved in polar transport.

     
    more » « less