@article{thomas_herrero_eng_gomaa_gillikin_noar_beseli_daub_2020, title={Engineering Cercospora disease resistance via expression of Cercospora nicotianae cercosporin-resistance genes and silencing of cercosporin production in tobacco}, volume={15}, ISSN={1932-6203}, url={http://dx.doi.org/10.1371/journal.pone.0230362}, DOI={10.1371/journal.pone.0230362}, abstractNote={Fungi in the genus Cercospora cause crop losses world-wide on many crop species. The wide host range and success of these pathogens has been attributed to the production of a photoactivated toxin, cercosporin. We engineered tobacco for resistance to Cercospora nicotianae utilizing two strategies: 1) transformation with cercosporin autoresistance genes isolated from the fungus, and 2) transformation with constructs to silence the production of cercosporin during disease development. Three C. nicotianae cercosporin autoresistance genes were tested: ATR1 and CFP, encoding an ABC and an MFS transporter, respectively, and 71cR, which encodes a hypothetical protein. Resistance to the pathogen was identified in transgenic lines expressing ATR1 and 71cR, but not in lines transformed with CFP. Silencing of the CTB1 polyketide synthase and to a lesser extent the CTB8 pathway regulator in the cercosporin biosynthetic pathway also led to the recovery of resistant lines. All lines tested expressed the transgenes, and a direct correlation between the level of transgene expression and disease resistance was not identified in any line. Resistance was also not correlated with the degree of silencing in the CTB1 and CTB8 silenced lines. We conclude that expression of fungal cercosporin autoresistance genes as well as silencing of the cercosporin pathway are both effective strategies for engineering resistance to Cercospora diseases where cercosporin plays a critical role.}, number={3}, journal={PLOS ONE}, publisher={Public Library of Science (PLoS)}, author={Thomas, Elizabeth and Herrero, Sonia and Eng, Hayde and Gomaa, Nafisa and Gillikin, Jeff and Noar, Roslyn and Beseli, Aydin and Daub, Margaret E.}, editor={Wilson, Richard A.Editor}, year={2020}, month={Mar}, pages={e0230362} } @article{selote_matthiadis_gillikin_sato_long_2018, title={The E3 ligase BRUTUS facilitates degradation of VOZ1/2 transcription factors}, volume={41}, ISSN={["1365-3040"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85050368197&partnerID=MN8TOARS}, DOI={10.1111/pce.13363}, abstractNote={AbstractBRUTUS (BTS) is an iron binding E3 ligase that has been shown to bind to and influence the accumulation of target basic helix‐loop‐helix transcription factors through 26S proteasome‐mediated degradation in Arabidopsis thaliana. Vascular Plant One‐Zinc finger 1 (VOZ1) and Vascular plant One‐Zinc finger 2 (VOZ2) are NAM, ATAF1/2 and CUC2 (NAC) domain transcription factors that negatively regulate drought and cold stress responses in plants and have previously been shown to be degraded via the 26S proteasome. However, the mechanism that initializes this degradation is unknown. Here, we show that BTS interacts with VOZ1 and VOZ2 and that the presence of the BTS RING domain is essential for these interactions. Through cell‐free degradation and immunodetection analyses, we demonstrate that BTS facilitates the degradation of Vascular plant One‐Zinc finger 1/2 (VOZ1/2) protein in the nucleus particularly under drought and cold stress conditions. In addition to its known role in controlling the iron‐deficiency response in plants, here, we report that BTS may play a role in drought and possibly other abiotic stress responses by facilitating the degradation of transcription factors, VOZ1/2.}, number={10}, journal={PLANT CELL AND ENVIRONMENT}, publisher={Wiley}, author={Selote, Devarshi and Matthiadis, Anna and Gillikin, Jeffrey W. and Sato, Masa H. and Long, Terri A.}, year={2018}, month={Oct}, pages={2463–2474} } @article{selote_samira_matthiadis_gillikin_long_2015, title={Iron-Binding E3 Ligase Mediates Iron Response in Plants by Targeting Basic Helix-Loop-Helix Transcription Factors}, volume={167}, ISSN={["1532-2548"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84920141665&partnerID=MN8TOARS}, DOI={10.1104/pp.114.250837}, abstractNote={AbstractIron uptake and metabolism are tightly regulated in both plants and animals. In Arabidopsis (Arabidopsis thaliana), BRUTUS (BTS), which contains three hemerythrin (HHE) domains and a Really Interesting New Gene (RING) domain, interacts with basic helix-loop-helix transcription factors that are capable of forming heterodimers with POPEYE (PYE), a positive regulator of the iron deficiency response. BTS has been shown to have E3 ligase capacity and to play a role in root growth, rhizosphere acidification, and iron reductase activity in response to iron deprivation. To further characterize the function of this protein, we examined the expression pattern of recombinant ProBTS::β-GLUCURONIDASE and found that it is expressed in developing embryos and other reproductive tissues, corresponding with its apparent role in reproductive growth and development. Our findings also indicate that the interactions between BTS and PYE-like (PYEL) basic helix-loop-helix transcription factors occur within the nucleus and are dependent on the presence of the RING domain. We provide evidence that BTS facilitates 26S proteasome-mediated degradation of PYEL proteins in the absence of iron. We also determined that, upon binding iron at the HHE domains, BTS is destabilized and that this destabilization relies on specific residues within the HHE domains. This study reveals an important and unique mechanism for plant iron homeostasis whereby an E3 ubiquitin ligase may posttranslationally control components of the transcriptional regulatory network involved in the iron deficiency response.}, number={1}, journal={PLANT PHYSIOLOGY}, author={Selote, Devarshi and Samira, Rozalynne and Matthiadis, Anna and Gillikin, Jeffrey W. and Long, Terri A.}, year={2015}, month={Jan}, pages={273-+} } @article{rueschhoff_gillikin_sederoff_daub_2013, title={The SOS4 pyridoxal kinase is required for maintenance of vitamin B-6-mediated processes in chloroplasts}, volume={63}, ISSN={["0981-9428"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84872415352&partnerID=MN8TOARS}, DOI={10.1016/j.plaphy.2012.12.003}, abstractNote={Vitamin B(6) (pyridoxal 5'-phosphate and its vitamers) is an important cofactor in numerous enzymatic reactions. In spite of its importance, the consequences of altering vitamin B(6) content on plant growth and development are not well understood. This study compares two mutants for vitamin B(6)-metabolizing enzymes in Arabidopsis thaliana: a pdx1.3 mutant in the de novo synthesis pathway and a salvage pathway sos4 mutant that accumulates more vitamin B(6). We show that despite a difference in total B(6) content in leaf tissue, both mutants share similar phenotypes, including chlorosis, decreased size, altered chloroplast ultrastructure, and root sensitivity to sucrose. Assay of B(6) vitamer content from isolated chloroplasts showed that, despite differing B(6) vitamer content in whole leaf tissue, both mutants share a common deficiency in total and phosphorylated vitamers in chloroplasts. One of the splice variants of the SOS4 proteins was shown to be located in the chloroplast. Our data indicate that some of the phenotypic consequences shared between the pdx1.3 and sos4 mutants are due to B(6) deficiency in chloroplasts, and show that SOS4 is required for maintenance of phosphorylated B(6) vitamer concentrations in chloroplasts. Further, our data are consistent with a diffusion model for transport of vitamin B(6) into chloroplasts.}, journal={PLANT PHYSIOLOGY AND BIOCHEMISTRY}, author={Rueschhoff, Elizabeth E. and Gillikin, Jeffrey W. and Sederoff, Heike W. and Daub, Margaret E.}, year={2013}, month={Feb}, pages={281–291} } @article{herrero_gonzalez_gillikin_velez_daub_2011, title={Identification and characterization of a pyridoxal reductase involved in the vitamin B6 salvage pathway in Arabidopsis}, volume={76}, ISSN={["1573-5028"]}, DOI={10.1007/s11103-011-9777-x}, abstractNote={Vitamin B6 (pyridoxal phosphate) is an essential cofactor in enzymatic reactions involved in numerous cellular processes and also plays a role in oxidative stress responses. In plants, the pathway for de novo synthesis of pyridoxal phosphate has been well characterized, however only two enzymes, pyridoxal (pyridoxine, pyridoxamine) kinase (SOS4) and pyridoxamine (pyridoxine) 5' phosphate oxidase (PDX3), have been identified in the salvage pathway that interconverts between the six vitamin B6 vitamers. A putative pyridoxal reductase (PLR1) was identified in Arabidopsis based on sequence homology with the protein in yeast. Cloning and expression of the AtPLR1 coding region in a yeast mutant deficient for pyridoxal reductase confirmed that the enzyme catalyzes the NADPH-mediated reduction of pyridoxal to pyridoxine. Two Arabidopsis T-DNA insertion mutant lines with insertions in the promoter sequences of AtPLR1 were established and characterized. Quantitative RT-PCR analysis of the plr1 mutants showed little change in expression of the vitamin B6 de novo pathway genes, but significant increases in expression of the known salvage pathway genes, PDX3 and SOS4. In addition, AtPLR1 was also upregulated in pdx3 and sos4 mutants. Analysis of vitamer levels by HPLC showed that both plr1 mutants had lower levels of total vitamin B6, with significantly decreased levels of pyridoxal, pyridoxal 5'-phosphate, pyridoxamine, and pyridoxamine 5'-phosphate. By contrast, there was no consistent significant change in pyridoxine and pyridoxine 5'-phosphate levels. The plr1 mutants had normal root growth, but were significantly smaller than wild type plants. When assayed for abiotic stress resistance, plr1 mutants did not differ from wild type in their response to chilling and high light, but showed greater inhibition when grown on NaCl or mannitol, suggesting a role in osmotic stress resistance. This is the first report of a pyridoxal reductase in the vitamin B6 salvage pathway in plants.}, number={1-2}, journal={PLANT MOLECULAR BIOLOGY}, author={Herrero, Sonia and Gonzalez, Eugenia and Gillikin, Jeffrey W. and Velez, Heriberto and Daub, Margaret E.}, year={2011}, month={May}, pages={157–169} } @article{kim_gibbon_gillikin_larkins_boston_jung_2006, title={The maize Mucronate mutation is a deletion in the 16-kDa gamma-zein gene that induces the unfolded protein response}, volume={48}, ISSN={["0960-7412"]}, DOI={10.1111/j.1365-313X.2006.02884.x}, abstractNote={Summary Mucronate (Mc) was identified as a dominant maize (Zea mays L.) opaque kernel mutation that alters zein storage protein synthesis. Zein protein bodies in Mc endosperm are misshapen and are associated with increased levels of ER Lumenal Binding Protein (BiP). Using GeneCallingTM to profile endosperm RNA transcripts, we identified an aberrant RNA in Mc that encodes the 16‐kDa γ‐zein protein. The transcript contains a 38‐bp deletion (nucleotides 406–444 after the initiation codon) that creates a frame‐shift mutation and an abnormal sequence for the last 63 amino acids. Genetic mapping revealed the Mc mutation is linked with the locus encoding the 16‐kDa γ‐zein, and two‐dimensional gel electrophoresis confirmed the 16‐kDa γ‐zein protein is altered in Mc. The mutant protein exhibited changes in solubility properties and co‐immunoprecipitated with the molecular chaperone, BiP. Transgenic maize plants expressing the Mc 16‐kDa γ‐zein manifested an opaque kernel phenotype with enhanced levels of BiP in the endosperm, similar to the Mc mutant. Unlike the wild‐type protein, the Mc 16‐kDa γ‐zein interacted only weakly with the 22‐kDa α‐zein when expressed in the yeast two‐hybrid system. These results indicate that the Mc phenotype results from a frame‐shift mutation in the gene encoding the 16‐kDa γ‐zein protein, leading to the unfolded protein response in developing endosperm.}, number={3}, journal={PLANT JOURNAL}, author={Kim, Cheol Soo and Gibbon, Bryan C. and Gillikin, Jeffrey W. and Larkins, Brian A. and Boston, Rebecca S. and Jung, Rudolf}, year={2006}, month={Nov}, pages={440–451} } @article{pagny_cabanes-macheteau_gillikin_leborgne-castel_lerouge_boston_faye_gomord_2000, title={Protein recycling from the Golgi apparatus to the endoplasmic reticulum in plants and its minor contribution to calreticulin retention}, volume={12}, ISSN={["1531-298X"]}, DOI={10.1105/tpc.12.5.739}, abstractNote={Using pulse–chase experiments combined with immunoprecipitation and N-glycan structural analysis, we showed that the retrieval mechanism of proteins from post–endoplasmic reticulum (post-ER) compartments is active in plant cells at levels similar to those described previously for animal cells. For instance, recycling from the Golgi apparatus back to the ER is sufficient to block the secretion of as much as 90% of an extracellular protein such as the cell wall invertase fused with an HDEL C-terminal tetrapeptide. Likewise, recycling can sustain fast retrograde transport of Golgi enzymes into the ER in the presence of brefeldin A. However, on the basis of our data, we propose that this retrieval mechanism in plants has little impact on the ER retention of a soluble ER protein such as calreticulin. Indeed, the latter is retained in the ER without any N-glycan–related evidence for a recycling through the Golgi apparatus. Taken together, these results indicate that calreticulin and perhaps other plant reticuloplasmins are possibly largely excluded from vesicles exported from the ER. Instead, they are probably retained in the ER by mechanisms that rely primarily on signals other than H/KDEL motifs.}, number={5}, journal={PLANT CELL}, author={Pagny, S and Cabanes-Macheteau, M and Gillikin, JW and Leborgne-Castel, N and Lerouge, P and Boston, RS and Faye, L and Gomord, V}, year={2000}, month={May}, pages={739–755} } @article{gillikin_zhang_coleman_bass_larkins_boston_1997, title={A defective signal peptide tethers the floury-2 zein to the endoplasmic reticulum membrane}, volume={114}, ISSN={["0032-0889"]}, DOI={10.1104/pp.114.1.345}, abstractNote={Abstract The maize (Zea mays L.) floury-2 (fl2) mutation is associated with a general decrease in storage protein synthesis, altered protein body morphology, and the synthesis of a novel 24-kD α--zein storage protein. Unlike storage proteins in normal kernels and the majority of storage proteins in fl2 kernels, the 24-kD α--zein contains a signal peptide that would normally be removed during protein synthesis and processing. The expected processing site of this α--zein reveals a putative mutation alaine->valine (Ala->Val) that is not found at other junctions between signal sequences and mature proteins. To investigate the impact of such a mutation on signal peptide cleavage, we have assayed the 24-kD fl2 α--zein in a co-translational processing system in vitro. Translation of RNA from fl2 kernels or synthetic RNA encoding the fl2 α--zein in the presence of microsomes yielded a 24-kD polypeptide. A normal signal peptide sequence, generated by site-directed mutagenesis, restored the capacity of the RNA to direct synthesis of a properly processed protein in a cell-free system. Both the fl2 α--zein and the fl2 α--zein (Val->Ala) were translocated into the lumen of the endoplasmic reticulum. The processed fl2 α--zein (Val->Ala) was localized in the soluble portion of the microsomes, whereas the fl2 α--zein co-fractionated with the microsomal membranes. By remaining anchored to protein body membranes during endosperm maturation, the fl2 zein may thus constrain storage protein packing and perturb protein body morphology.}, number={1}, journal={PLANT PHYSIOLOGY}, author={Gillikin, JW and Zhang, F and Coleman, CE and Bass, HW and Larkins, BA and Boston, RS}, year={1997}, month={May}, pages={345–352} } @article{boston_gillikin_wrobel_zhang_1997, title={Molecular chaperone activity of er-resident proteins in seeds}, volume={16}, number={1997}, journal={Current Topics in Plant Biochemistry and Physiology}, author={Boston, R. S. and Gillikin, J. W. and Wrobel, R. L. and Zhang, F.}, year={1997}, pages={3–4} }