Publications by authors named "Pengchao Hao"

12 Publications

  • Page 1 of 1

Effect of catalyst and reaction conditions on aromatic monomer yields, product distribution, and sugar yields during lignin hydrogenolysis of silver birch wood.

Bioresour Technol 2020 Nov 28;316:123907. Epub 2020 Jul 28.

Chemical & Biological Engineering Department, Montana State University, United States; Division of Sustainable Process Engineering, Luleå University of Technology, Luleå, Sweden. Electronic address:

The impact of catalyst choice and reaction conditions during catalytic hydrogenolysis of silver birch biomass are assessed for their effect on aromatic monomer yields and selectivities, lignin removal, and sugar yields from enzymatic hydrolysis. At a reaction temperature of 220 °C with no supplemental H, it was demonstrated that both Co/C and Ni/C exhibited aromatic monomer yields of >50%, which were close to the theoretical maximum expected for the lignin based on total β-O-4 content and exhibited high selectivities for 4-propylguaiacol and 4-propylsyringol. Pd/C exhibited a significantly different set of products, and using a model lignin dimer, showed a product profile that shifted upon inclusion of supplemental H, suggesting that the generation of surface hydrogen is critical for this catalyst system. Lignin removal during hydrogenolysis could be correlated to glucose yields and inclusion of lignin depolymerizing catalysts significantly improves lignin removal and subsequent enzymatic hydrolysis yields.
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http://dx.doi.org/10.1016/j.biortech.2020.123907DOI Listing
November 2020

Auxin-transporting ABC transporters are defined by a conserved D/E-P motif regulated by a prolylisomerase.

J Biol Chem 2020 09 22;295(37):13094-13105. Epub 2020 Jul 22.

Department of Biology, University of Fribourg, Fribourg, Switzerland. Electronic address:

The plant hormone auxin must be transported throughout plants in a cell-to-cell manner to affect its various physiological functions. ABCB transporters are critical for this polar auxin distribution, but the regulatory mechanisms controlling their function is not fully understood. The auxin transport activity of ABCB1 was suggested to be regulated by a physical interaction with FKBP42/Twisted Dwarf1 (TWD1), a peptidylprolyl isomerase (PPIase), but all attempts to demonstrate such a PPIase activity by TWD1 have failed so far. By using a structure-based approach, we identified several surface-exposed proline residues in the nucleotide binding domain and linker of Arabidopsis ABCB1, mutations of which do not alter ABCB1 protein stability or location but do affect its transport activity. P1008 is part of a conserved signature D/E-P motif that seems to be specific for uxin-ransporting BCBs, which we now refer to as ATAs. Mutation of the acidic residue also abolishes auxin transport activity by ABCB1. All higher plant ABCBs for which auxin transport has been conclusively proven carry this conserved motif, underlining its predictive potential. Introduction of this D/E-P motif into malate importer, ABCB14, increases both its malate and its background auxin transport activity, suggesting that this motif has an impact on transport capacity. The D/E-P1008 motif is also important for ABCB1-TWD1 interactions and activation of ABCB1-mediated auxin transport by TWD1. In summary, our data imply a new function for TWD1 acting as a putative activator of ABCB-mediated auxin transport by isomerization of peptidyl-prolyl bonds.
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http://dx.doi.org/10.1074/jbc.RA120.014104DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7489919PMC
September 2020

Biomimetic Reductive Cleavage of Keto Aryl Ether Bonds by Small-Molecule Thiols.

ChemSusChem 2019 Nov 11;12(21):4775-4779. Epub 2019 Sep 11.

Department of Biochemistry & Molecular Biology, Michigan State University, 603 Wilson Rd, East Lansing, Michigan, 48824, USA.

The nucleophilic and reductive properties of thiolates and thiols make them ideal candidates as redox mediators via the thiol/disulfide couple. One mechanism for biological lignin depolymerization entails reduction of keto aryl ether bonds by an S 2 mechanism with the thiol redox mediator glutathione. In this study, mimicking this chemistry in a simple protein- and metal-free process, several small organic thiols are surveyed for their ability to cleave aryl keto ethers that model the β-O-4 linkages found in partially oxidized lignin. In polar aprotic solvents, β-mercaptoethanol and dithiothreitol yielded up to 100 % formation of phenol and acetophenone products from 2-phenoxyacetophenone, but not from its reduced alcohol congener. The effects of reaction conditions and of substituents on the aryl rings and the keto ether linkage are assessed. These results, together with activation barriers computed by quantum chemical simulations and direct observation of the expected intermediate thioether, point to an S 2 mechanism. This study confirms that small organic thiols can reductively break down lignin-relevant keto aryl ether linkages.
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http://dx.doi.org/10.1002/cssc.201901742DOI Listing
November 2019

A transportome-scale amiRNA-based screen identifies redundant roles of Arabidopsis ABCB6 and ABCB20 in auxin transport.

Nat Commun 2018 10 11;9(1):4204. Epub 2018 Oct 11.

School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, 69978, Israel.

Transport of signaling molecules is of major importance for regulating plant growth, development, and responses to the environment. A prime example is the spatial-distribution of auxin, which is regulated via transporters to govern developmental patterning. A critical limitation in our ability to identify transporters by forward genetic screens is their potential functional redundancy. Here, we overcome part of this functional redundancy via a transportome, multi-targeted forward-genetic screen using artificial-microRNAs (amiRNAs). We generate a library of 3000 plant lines expressing 1777 amiRNAs, designed to target closely homologous genes within subclades of transporter families and identify, genotype and quantitatively phenotype, 80 lines showing reproducible shoot growth phenotypes. Within this population, we discover and characterize a strong redundant role for the unstudied ABCB6 and ABCB20 genes in auxin transport and response. The unique multi-targeted lines generated in this study could serve as a genetic resource that is expected to reveal additional transporters.
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http://dx.doi.org/10.1038/s41467-018-06410-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6182007PMC
October 2018

Tomato ATP-Binding Cassette Transporter SlABCB4 Is Involved in Auxin Transport in the Developing Fruit.

Plants (Basel) 2018 Aug 13;7(3). Epub 2018 Aug 13.

Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan.

Plant ATP binding cassette (ABC) transporters are membrane proteins that are important for transporting a wide range of compounds, including secondary metabolites and phytohormones. In Arabidopsis, some members of the ABCB subfamily of ABC transporter, also known as Multi-Drug Resistance proteins (MDRs), have been implicated in auxin transport. However, reports on the roles of the auxin-mediated ABCBs in fleshy fruit development are rare. Here, we present that SlABCB4, a member of the tomato ABCB subfamily, transports auxin in the developing fruit of tomato. Transient expression of SlABCB4-GFP fusion proteins in tobacco cells showed plasma membrane localization. The transport activity of SlABCB4, expressed in protoplasts, revealed substrate specificity for indole-3-acetic acid export. Gene expression analysis of SlABCB4 revealed high expression levels at the early stages of fruit development. Therefore, SlABCB4 is considered to facilitate auxin distribution in tomato fruit, which is important for tomato fruit development.
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http://dx.doi.org/10.3390/plants7030065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6161087PMC
August 2018

A Critical View on ABC Transporters and Their Interacting Partners in Auxin Transport.

Plant Cell Physiol 2017 Oct;58(10):1601-1614

University of Fribourg, Department of Biology, CH-1700 Fribourg, Switzerland.

Different subclasses of ATP-binding cassette (ABC) transporters have been implicated in the transport of native variants of the phytohormone auxin. Here, the putative, individual roles of key members belonging to the ABCB, ABCD and ABCG families, respectively, are highlighted and the knowledge of their assumed expression and transport routes is reviewed and compared with their mutant phenotypes. Protein-protein interactions between ABC transporters and regulatory components during auxin transport are summarized and their importance is critically discussed. There is a focus on the functional interaction between members of the ABCB family and the FKBP42, TWISTED DWARF1, acting as a chaperone during plasma membrane trafficking of ABCBs. Further, the mode and relevance of functional ABCB-PIN interactions is diagnostically re-evaluated. A new nomenclature describing precisely the most likely ABCB-PIN interaction scenarios is suggested. Finally, available tools for the detection and prediction of ABC transporter interactomes are summarized and the potential of future ABC transporter interactome maps is highlighted.
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http://dx.doi.org/10.1093/pcp/pcx104DOI Listing
October 2017

TWISTED DWARF1 Mediates the Action of Auxin Transport Inhibitors on Actin Cytoskeleton Dynamics.

Plant Cell 2016 04 6;28(4):930-48. Epub 2016 Apr 6.

Department of Biology, University of Fribourg, CH-1700 Fribourg, Switzerland Department of Plant and Microbial Biology, University of Zurich, CH-8008 Zurich, Switzerland

Plant growth and architecture is regulated by the polar distribution of the hormone auxin. Polarity and flexibility of this process is provided by constant cycling of auxin transporter vesicles along actin filaments, coordinated by a positive auxin-actin feedback loop. Both polar auxin transport and vesicle cycling are inhibited by synthetic auxin transport inhibitors, such as 1-N-naphthylphthalamic acid (NPA), counteracting the effect of auxin; however, underlying targets and mechanisms are unclear. Using NMR, we map the NPA binding surface on the Arabidopsis thaliana ABCB chaperone TWISTED DWARF1 (TWD1). We identify ACTIN7 as a relevant, although likely indirect, TWD1 interactor, and show TWD1-dependent regulation of actin filament organization and dynamics and that TWD1 is required for NPA-mediated actin cytoskeleton remodeling. The TWD1-ACTIN7 axis controls plasma membrane presence of efflux transporters, and as a consequence act7 and twd1 share developmental and physiological phenotypes indicative of defects in auxin transport. These can be phenocopied by NPA treatment or by chemical actin (de)stabilization. We provide evidence that TWD1 determines downstream locations of auxin efflux transporters by adjusting actin filament debundling and dynamizing processes and mediating NPA action on the latter. This function appears to be evolutionary conserved since TWD1 expression in budding yeast alters actin polarization and cell polarity and provides NPA sensitivity.
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http://dx.doi.org/10.1105/tpc.15.00726DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4863381PMC
April 2016

Integrated Proteome Analysis of the Wheat Embryo and Endosperm Reveals Central Metabolic Changes Involved in the Water Deficit Response during Grain Development.

J Agric Food Chem 2015 Sep 15;63(38):8478-87. Epub 2015 Sep 15.

College of Life Sciences, Capital Normal University , Beijing 100048, China.

The embryo and endosperm of wheat have different physiological functions and large differences in protein level. In this study, we performed the first integrated proteome analysis of wheat embryo and endosperm in response to the water deficit during grain development. In total, 155 and 130 differentially expressed protein (DEP) spots in the embryo and endosperm, respectively, were identified by nonlinear two-dimensional electrophoresis and tandem mass spectrometry. These DEPs in the embryo were mainly involved in stress/defense responses such as heat shock-related proteins (HSP) and peroxidase, whereas those in endosperm were mainly related to starch and storage protein synthesis such as α-amylase inhibitor and the globulin-1 S allele. In particular, some storage proteins such as avenin-like proteins and high-molecular weight glutenin subunit Dy12 displayed higher expression levels in the mature endosperm under a water deficit, which might contribute to the improvement in the quality of breadmaking.
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http://dx.doi.org/10.1021/acs.jafc.5b00575DOI Listing
September 2015

An integrative proteome analysis of different seedling organs in tolerant and sensitive wheat cultivars under drought stress and recovery.

Proteomics 2015 May;15(9):1544-63

College of Life Science, Capital Normal University, Beijing, P. R. China.

Roots, leaves, and intermediate sections between roots and leaves (ISRL) of wheat seedlings show different physiological functions at the protein level. We performed the first integrative proteomic analysis of different tissues of the drought-tolerant wheat cultivar Hanxuan 10 (HX-10) and drought-sensitive cultivar Chinese Spring (CS) during a simulated drought and recovery. Differentially expressed proteins (DEPs) in the roots (122), ISRLs (146), and leaves (163) showed significant changes in expression in response to drought stress and recovery. Numerous DEPs associated with cell defense and detoxifications were significantly regulated in roots and ISRLs, while in leaves, DEPs related to photosynthesis showed significant changes in expression. A significantly larger number of DEPs related to stress defense were upregulated in HX-10 than in CS. Expression of six HSPs potentially related to drought tolerance was significantly upregulated under drought conditions, and these proteins were involved in a complex protein-protein interaction network. Further phosphorylation analysis showed that the phosphorylation levels of HSP60, HSP90, and HOP were upregulated in HX-10 under drought stress. We present an overview of metabolic pathways in wheat seedlings based on abscisic acid signaling and important protein expression patterns.
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http://dx.doi.org/10.1002/pmic.201400179DOI Listing
May 2015

Molecular cloning, phylogenetic analysis, and expression profiling of endoplasmic reticulum molecular chaperone BiP genes from bread wheat (Triticum aestivum L.).

BMC Plant Biol 2014 Oct 1;14:260. Epub 2014 Oct 1.

Background: The endoplasmic reticulum chaperone binding protein (BiP) is an important functional protein, which is involved in protein synthesis, folding assembly, and secretion. In order to study the role of BiP in the process of wheat seed development, we cloned three BiP homologous cDNA sequences in bread wheat (Triticum aestivum), completed by rapid amplification of cDNA ends (RACE), and examined the expression of wheat BiP in wheat tissues, particularly the relationship between BiP expression and the subunit types of HMW-GS using near-isogenic lines (NILs) of HMW-GS silencing, and under abiotic stress.

Results: Sequence analysis demonstrated that all BiPs contained three highly conserved domains present in plants, animals, and microorganisms, indicating their evolutionary conservation among different biological species. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) revealed that TaBiP (Triticum aestivum BiP) expression was not organ-specific, but was predominantly localized to seed endosperm. Furthermore, immunolocalization confirmed that TaBiP was primarily located within the protein bodies (PBs) in wheat endosperm. Three TaBiP genes exhibited significantly down-regulated expression following high molecular weight-glutenin subunit (HMW-GS) silencing. Drought stress induced significantly up-regulated expression of TaBiPs in wheat roots, leaves, and developing grains.

Conclusions: The high conservation of BiP sequences suggests that BiP plays the same role, or has common mechanisms, in the folding and assembly of nascent polypeptides and protein synthesis across species. The expression of TaBiPs in different wheat tissue and under abiotic stress indicated that TaBiP is most abundant in tissues with high secretory activity and with high proportions of cells undergoing division, and that the expression level of BiP is associated with the subunit types of HMW-GS and synthesis. The expression of TaBiPs is developmentally regulated during seed development and early seedling growth, and under various abiotic stresses.
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http://dx.doi.org/10.1186/s12870-014-0260-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4189733PMC
October 2014

Dynamic development of starch granules and the regulation of starch biosynthesis in Brachypodium distachyon: comparison with common wheat and Aegilops peregrina.

BMC Plant Biol 2014 Aug 6;14:198. Epub 2014 Aug 6.

Background: Thorough understanding of seed starch biosynthesis and accumulation mechanisms is of great importance for agriculture and crop improvement strategies. We conducted the first comprehensive study of the dynamic development of starch granules and the regulation of starch biosynthesis in Brachypodium distachyon and compared the findings with those reported for common wheat (Chinese Spring, CS) and Aegilops peregrina.

Results: Only B-granules were identified in Brachypodium Bd21, and the shape variation and development of starch granules were similar in the B-granules of CS and Bd21. Phylogenetic analysis showed that most of the Bd21 starch synthesis-related genes were more similar to those in wheat than in rice. Early expression of key genes in Bd21 starch biosynthesis mediate starch synthesis in the pericarp; intermediate-stage expression increases the number and size of starch granules. In contrast, these enzymes in CS and Ae. peregrina were mostly expressed at intermediate stages, driving production of new B-granules and increasing the granule size, respectively. Immunogold labeling showed that granule-bound starch synthase (GBSSI; related to amylose synthesis) was mainly present in starch granules: at lower levels in the B-granules of Bd21 than in CS. Furthermore, GBSSI was phosphorylated at threonine 183 and tyrosine 185 in the starch synthase catalytic domain in CS and Ae. peregrina, but neither site was phosphorylated in Bd21, suggesting GBSSI phosphorylation could improve amylose biosynthesis.

Conclusions: Bd21 contains only B-granules, and the expression of key genes in the three studied genera is consistent with the dynamic development of starch granules. GBSSI is present in greater amounts in the B-granules of CS than in Bd21; two phosphorylation sites (Thr183 and Tyr185) were found in Triticum and Aegilops; these sites were not phosphorylated in Bd21. GBSSI phosphorylation may reflect its importance in amylose synthesis.
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http://dx.doi.org/10.1186/s12870-014-0198-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4256708PMC
August 2014

iTRAQ-based quantitative proteomic analysis reveals new metabolic pathways of wheat seedling growth under hydrogen peroxide stress.

Proteomics 2013 Oct 13;13(20):3046-58. Epub 2013 Sep 13.

College of Life Sciences, Capital Normal University, Beijing, China.

As an abundant ROS, hydrogen peroxide (H2 O2 ) plays pivotal roles in plant growth and development. In this work, we conducted for the first time an iTRAQ-based quantitative proteomic analysis of wheat seedling growth under different exogenous H2 O2 treatments. The growth of seedlings and roots was significantly restrained by increased H2 O2 concentration stress. Malondialdehyde, soluble sugar, and proline contents as well as peroxidase activity increased with increasing H2 O2 levels. A total of 3,425 proteins were identified by iTRAQ, of which 157 showed differential expression and 44 were newly identified H2 O2 -responsive proteins. H2 O2 -responsive proteins were mainly involved in stress/defense/detoxification, signal transduction, and carbohydrate metabolism. It is clear that up-regulated expression of signal transduction and stress/defence/detoxification-related proteins under H2 O2 stress, such as plasma membrane intrinsic protein 1, fasciclin-like arabinogalactan protein, and superoxide dismutase, could contribute to H2 O2 tolerance of wheat seedlings. Increased gluconeogenesis (phosphoenol-pyruvate carboxykinase) and decreased pyruvate kinase proteins are potentially related to the higher H2 O2 tolerance of wheat seedlings. A metabolic pathway of wheat seedling growth under H2 O2 stress is presented.
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http://dx.doi.org/10.1002/pmic.201300042DOI Listing
October 2013
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