Guru Rao

Guru 2015 - Cropped 091115


  • Structure-function relationships of plant proteins
  •  Protein-protein interactions in plant signal transduction
  •  Protein engineering

1210 Molecular Biology Building
Dept. of Biochemistry, Biophysics & Molecular Biology
Iowa State University
Ames, IA  50011

Lab #0049
Roy J Carver Co-labs
Ames, IA  50011-3650

Phone: (515) 294-6116


Ph.D., Biochemistry, University of Mysore, India, 1981
Postdoctoral Fellow, Case Western University, 1980-1983
Research Assistant Professor, University of South Carolina (Columbia, SC) 1983-87

Research Interests

Our research interests in protein science are broad, with an emphasis on the biochemical characterization of proteins to establish structure-activity relationships, protein engineering for altering protein function, protein folding, protein stability and protein-protein interactions. As the genome sequencing projects ‘unravel’ the primary structure of proteins, the crux of the issue becomes not the sequence per se but the characterization of proteins (i.e. post-translational modifications) and establishing function not only in isolation but through a network of interactions. Elucidation of the signal transduction pathways is expected to provide key insights into strategies to produce grain for food, feed and renewable fuels.

Signal transduction in plants

  1. Cell surface receptor-mediated perception of signals is a common theme among living
    organisms. In animals, cellular signaling occurs predominantly through tyrosine kinase activity.
    In contrast, in plants, all available information indicates that serine/threonine kinase activity is exclusively
    used in signal transduction. One member of the ser/thr receptor-like kinase (RLK) family in plants
    is crinkly4 (CR4). The crinkly4 gene, encodes a tumor necrosis factor like (TNFR-like) receptor
    kinase CR4, which has beensuggested to participate in an as yet unidentified ligand-induced
    signal for aleurone differentiation in maize seeds (Becraft et al., 1996). The homolog in Arabidopsis
    is designated as ACR4. The objectives in my research program are to apply biochemical and biophysical
    techniques to understand the structure-function properties of ACR4 and to delineate the downstream
    protein-protein interactions mediated by the kinase domain. Elucidation of the signal transduction pathways
    in seed development is expected to provide key insights into novel strategies to produce grain for food, feed
    and renewable fuels.
  2. The second project is a collaborative project with Applied Biotechnology Institute in California and is focused on the biochemical and biophysical characterization of Hepatitis B Surface Antigen (HBsAg) expressed in maize.  Hepatitis B is an infectious disease of the liver caused by the Hepatitus B virus.  The Hepatitis B surface antigen (HBsAg) is a lipoprotein antigen of the virus and is associated with the early symptoms of the disease.  Tests for serum HBsAg are used in the diagnosis of acute or chronic Hepatitis B and in testing blood products for infectivity.  The antigen is an effective vaccine for the treatment of this widespread disease and a safe and immunogenic form of the protein has been recombinantly expressed/purified from yeast.  This protein has been used as a parenteral vaccine for over 20 years.  More recently, the antigen has been produced in maize.  The primary goal of this project is to characterize HBsAg purified from maize grain in terms of primary, secondary, and tertiary structure using a variety of biochemical and biophysical techniques.  Applied Biotechnology Institute (ABI) will provide raw material for the investigations in addition to protocols/techniques, such as immunochemical methods, to aid in the characterization of the protein.  The properties of the maize-derived HBsAg will then be compared to the protein produced from yeast. Our preliminary studies received extensive press coverage at the Experimental Biology 2015 meeting in Boston in March 2015 (

Research Funding 

1.  Gateways for photoperiod-mediated RNA trafficking (P.I., David Hannapel; Co-P.I., Guru Rao)USDA-NRI-CGP,
$400,000 for the period 2008-2012.

2.  Transferring research from a model system to uncover the network that regulates long-distance signaling in
potato (P.I., David Hannapel (ISU) ; Co-P.I’s: Guru Rao (ISU); William J. Lucas (U.C. Davis); Jeffery Coller (CWRU).
NSF, Plant Genome Research Program. $2.76M for the period 2008-2012.

3.  A comprehensive application of phage display for high throughput screening and affinity selection of
protein/peptide ligands (P.I. Guru Rao). Funding from Archer Daniels Midland (ADM), $489,469 for the period
1/1/2011 through 12/31/2013.

Selected Publications

2015.  Yue, K., Sandal, P., et al. Reciprocal regulation between ACR4 and PP2A-3 regulates formative cell divisions
in the Arabidopsis root (Submitted).

2015.  Shah, S., Hayden, C.A., Fischer, M.E., Rao, A.G., Howard, J.A. Biochemical and Biophysical Characterization
of Maize-derived HBsAg for the Development of an Oral Vaccine. (Submitted).

2015.  Cho, S.K., Sharma, P., Butler, N.M., Kang, I.H., Shah, S., Rao, A.G., Hannapel, D.J. Polypyrimidine
tract-binding proteins of potato mediate tuberization through an interaction with StBEL5 RNA. J. Exp. Bot. August 17
(ePublication ahead of print).

2015.  Meyer, M.R., Shah, S., Zhang, J., Rohrs, H & Rao, A.G. Evidence for intermolecular interactions between the
intracellular domains of the Arabidopsis Receptor-like kinase ACR4, its homologs and Wox5 transcription factor.
PLoS One 10(3)
: e0118861.

2013.  Shah, S., Butler, N.M., Hannapel, D.J., & Rao, A.G. Mapping and Characterization of the interaction interface
between two polypyrimidine-tract binding proteins and a Nova-type protein of Solanum tuberosum.
PLoS One 8(5)
: e64783.

2013.  Meyer, M.R., Shah, S., & Rao, A.G. Insights into molecular interactions between the juxtamembrane and kinase subdomains of the Arabidopsis Crinkly-4 receptor-like kinase. Arch Biochem. Biophys. 535: 101-110.

2013.  Srivastava, R., Deng, Y., Shah, S., Rao, A.G., Howell, S.H. BINDING PROTEIN Is a Master Regulator of the
Endoplasmic Reticulum Stress Sensor/Transducer bZIP28 in Arabidopsis. Plant Cell. 25: 1416-29.

2011.  Meyer, M.R., Lichti, C.F., Townsend, R.R., & Rao, A.G. Identification of in vitro autophosphorylation sites and the
effects of phosphorylation on the Arabidopsis Crinkly4 (ACR4) receptor-like kinase intracellular domain: insights into
conformation, oligomerization and activity. Biochemistry 50: 2170-2186.

2011.  Shah, S., Lee, Y-J., Hannapel, D.J. & Rao, A.G. Protein profiling of the potato petiole under short day and long day photoperiods. J of Proteomics 74: 212-230.

2010.  Stokes, K.D., & Rao, A.G. The role of individual amino acids in the dimerization of CR4 and ACR4 transmembrane domains. Arch. Biochem. Biophys. 502, 104-111.

2008.  Stokes, K.D., & Rao, A.G. Dimerization properties of the transmembrane domains of Arabidopsis CRINKLY4 receptor-like kinase and homologs. Arch. Biochem. Biophys. 477, p. 219.

2008.  Rao, A.G. The outlook for protein engineering in crop improvement. Plant Physiol., 147, p. 6  (Invited Review)

Invited Talks

2007 – Engineering proteins for nutritional value. International meeting of the Crop Science Society of America,
New Orleans, November 4-8.

2005 – Improving the Plant Secretory System for Nutrition and Health. Mini-symposium organized by the Rank
Prize Funds, Grasmere, U.K., May 23-26.


2010 – Provisional patent application “Peptide Domains that Bind Small Molecules of Industrial Significance”

2009 – Isolated polynucleotide molecules corresponding to mutant and wild-type alleles of the maize D9 gene and
methods of use (patent # 7,557,266)

2007 – Expression cassettes for producing plants with increased levels of essential amino acids (patent # 7,211,431 B2)

2007 – Altering protein functional properties through terminal fusions (patent # 7,160,988)

2007 – Method for integration of foreign DNA into eukaryotic genomes (patent # 7223601)

2006 – Alteration of amino acid composition in seeds (patent # 7053282)

2005 – Composition and methods for altering amino acid content of proteins (patent # 6905877)

2004 – Novel high lysine proteins (patent # 6,800,726)

2001 – Amino polyol amine oxidase and related polypeptides and methods of use (patent # 6211434).

2001 – Method for integration of foreign DNA into eukaryotic genome (patent # 6262341)

2000 – Peptide derivatives of tachyplesin having antimicrobial activity (patent # 6015941).

1999 – Derivatives of Bauhinia purpurea lectin and their use as larvicides (patent # 5945589)

1999 – High lysine derivatives of -hordothionin (patent # 5990389)

1999 – High threonine derivatives of -hordothionin (patent # 5885801)

1999 – High methionine derivatives of -hordothionin(patent # 5885802)

1998 – Commercial production of aprotinin in plants (patent # 5824870)

1997 –  Methionine derivatives of hordothionin for pathogen control (patent # 5703049)

1997 – Synthetic antimicrobial peptides (patent # 5607914 and 5717061)

1996 – Peptide derives. of Tachyplesin having inhibitory activity towards plant pathogenic fungi (patent # 5580852)

1996 – Peptide with inhibitory activity towards plant pathogenic fungi (patent # 5488035)

1995 – Synthetic antifungal peptides (patent # 5464944)

1995 – Larvicidal Lectins and Plant Insect Resistance Based Thereon (patent # 5407454)