| Michael Held
Department of Chemistry and Biochemistry
Biochemistry Research Facility Rm 118
350 W. State St.
Athens, OH 45701
Plant cell walls are composed of polymeric networks of cellulose, crosslinking glycans, matrix polysaccharides, structural glycoproteins, and crosslinking phenolic compounds. With few exceptions, cell wall components are synthesized in the plant Golgi apparatus and targeted to the cell wall via the secretory pathway. Understanding the mechanisms that govern both the biosynthesis and the trafficking of these polymers are the principle research areas of interest in my lab. Plant cell wall biosynthesis is a highly coordinated process at the level of gene expression. Using an approach called virus-induced gene silencing (VIGS) in barley and wheat, we are investigated the transcriptional and post-transcriptional responses to silencing various components of cell wall biosynthetic machinery. The consequences that silencing these genes have on cell wall biosynthesis are also being examined. Plant cell wall biosynthesis is also coordinated at the protein catalytic level. Evidence indicates that many cell wall biosynthetic enzymes participate as part of multi-subunit complexes. Using various cell biological and proteomic techniques, we are studying the nature of these enzyme complexes in order to gain a better understanding of the mechanisms of biosynthesis as well as trafficking.
Debarati Basu, Yan Liang, Xiao Liu, Klaus Himmeldirk, Ahmed Faik, Marcia Kieliszewski, Michael Held, and Allan M. Showalter (2013) Functional Identification of a Hydroxyproline-O- Galactosyltransferase Specific for Arabinogalactan-Protein Biosynthesis in Arabidopsis. J. Biol. Chem, Accepted Feb 19.
SFederica Brandizzi and Michael A. Held (2012) “This study demonstrates that members of the GT61 glycosyltransferase family in both wheat and rice are able to catalyze the addition of arabinofuranosyl units onto a xylan backbone.” Evaluation of: [Anders N et al. Glycosyl transferases in family 61 mediate arabinofuranosyl transfer onto xylan in grasses. Proc Natl Acad Sci U S A. 2012 Jan 17; 109(3):989-93; doi: 10.1073/pnas.1115858109].Faculty of 1000 Cell Biology, Mar 13, 2012.
Renata Conger, Yani Chen, Silvia Fornaciari, Carmen Faso, Michael Held, Luciana Renna and Federica Brandizzi (2011) Evidence for the involvement of the Arabidopsis Sec24A, a component of the COPII coat, in pollen germination. J. Exp Bot. 62, 4017-26.
Erin Slabaugh, Michael Held, and Federica Brandizzi (2011) Control of root hair development in Arabidopsis thaliana by an endoplasmic reticulum-anchored member of the R2R3-MYB transcription factor. Plant J. 67, 395-405 (COVER ARTICLE)
Michael A. Held, Evan Be, Starla Zemelis, Saunia Withers, Curtis Wilkerson, and Federica Brandizzi (2011) CGR3: A Golgi-localized protein influencing homogalacturonan methylesterification. Mol. Plant 4, 832-44..
Miaoying Tian, Joe Win, Elizabeth Savory, Michael Held, Federica Brandizzi, Sophien Kamoun, and Brad Day (2011) 454 genome sequencing of Pseudoperonospora cubensis reveals effector proteins with a putative QXLR translocation motif. Molecular Plant-Microbe Interactions (Accepted Jan. 7, 2011).
Lucia Marti, Giovanni Stefano, Kentaro Tamura, Chris Hawes, Luciana Renna, Michael Held and Federica Brandizzi (2010) A novel missense mutation in the vacuolar protein GOLD36 causes organizational defects in the ER and aberrant protein trafficking in the plant secretory pathway. Plant J. 63, 901
Carmen Faso, Yani Chen, Kentaro Tamura, Michael A. Held, Starla Zemelis, RamuSubramanian Saravanan, Eric Hummel, Leslie Kung, Elizabeth Miller, Chris Hawes and Federica Brandizzi (2009) A missense mutation in the Arabidopsis COPII coat protein Sec24A induces the formation of clusters of the endoplasmic reticulum and Golgi apparatus. Plant Cell 21, 3655.
Michael A. Held, Bryan Penning, Amanda S. Brandt, Sarah A. Kessans, Weidong Yong, Steven R. Scofield and Nicholas C. Carpita. (2008) Small-interfering RNAs from natural antisense transcripts derived from a cellulose synthase gene modulate cell wall biosynthesis in barley. Proc Nat Acad Sci USA 105, 20534.
Michael A. Held, Aurelia Boulaflous, and Federica Brandizzi. (2008) Advances in Fluorescent Protein-Based Imaging for the Analysis of Plant Endomembranes. Plant Physiol. 147, 1469-1481.
Sally L. Hanton, Laurent Chatre, Loren Matheson, Marika Rossi, Michael A. Held, and Federica Brandizzi. (2008) Plant SAR1 Isoforms with near-identical protein sequences exhibit different localisations and effects on secretion. Plant Mol. Bio. 67, 283-294.
Athikkattuvalasu S. Karthikeyan, Deepa K. Varadarajan, Ajay Jain, Michael A. Held, Nicholas C. Carpita and Kashchandra G. Raghothama. (2007) Phosphate starvation response and sugar signaling in Arabidopsis. Planta 225, 907-918.
Ben Wegenhart, Li Tan, Michael Held, Marcia Kieliszewski, and Liwei Chen. (2006) Aggregate structure of hydroxyproline-rich glycoprotein (HRGP) and HRGP assisted dispersion of carbon nanotubes. Nanoscale Res. Lett. 1, 154-159.
Michael A. Held, Li Tan, Abdolreza Kamyab, Michael Hare, Elena Shpak, and Marcia J. Kieliszewski. (2004) Di-isodityrosine Is the Intermolecular Cross-link of Isodityrosine-rich Extensin Analogs Cross-linked in Vitro. J. Biol. Chem. 279, 55474-55482.
Patents Marcia J. Kieliszewski and Michael A. Held. "Cross-Linkable Glycoproteins and Methods of Making the Same." US20080262198. Filed April 19, 2004.