Biochemistry

Joseph C. Polacco

Professor Emeritus of Biochemistry

E-mail:polaccoj@missouri.edu

Mail: Biochemistry
117 Schweitzer Hall
University of Missouri
Columbia, MO 65211

Phone: 573-882-4845

Fax: 573-882-5635

Lab: 573-882-9940

Educational background

Notable honors and service

• Fulbright Research Awards (2000, 2005)

Research description

A long-standing interest of the Polacco lab has been on the assimilatory roles, and Ni activation, of the soybean ureases. In the former, he is currently collaborating with Kristin D. Bilyeu (USDA-Agronomy) on elucidating differential expression of two paralogous genes (UreF) involved urease activation. Both encode functional proteins, but the expression of one gene is suppressed by poor translation due to an upstream in-frame ATG in the processed transcript.

As of 2010 Polacco is refocusing his interest in ureases on their insecticidal, inflammatory, and fungitoxic properties. In collaboration with Brazilian labs (of Celia Carlini, Giancarlo Pasquali and Maria-Helena Zanettini of the Universidade Federal do Rio Grande do Sul) modes of action, and target sites are being investigated.

While the physiological roles of ureases in plants are no longer a major research thrust by Polacco, there are still interesting remaining questions. Is arginine both a source of urea (proven) and nitric oxide (NO, unproven) in plants? Mutants lacking either of the Arabidopsis arginases appear to produce more NO, manifested by a fluorescence assay as well as a greater propensity to form lateral roots in response to external auxin. Possible NOS-arginase interactions are now being examined.

The Polacco group, in collaboration with Kristin Bilyeu (MU USDA and Agronomy), has developed a low phytic acid soybean line that produces a phytase in the developing embryo. The enzyme remains active in the mature seed, allowing use of its meal to lower phytic acid in meals of other grains in feed mixtures.

Selected publications

Tovar-Mendez A, Todd CD and Polacco JC. The mitochondrial connection: Arginine degradation versus arginine conversion to nitric oxide. Plant Signaling and Behavior 2008;3:1106-1108.

Flores T, Todd CD, Tovar-Mendez A, Dhanoa PK, Correa-Aragunde N, Hoyos ME, Brownfield DM, Mullen RT, Lamattina L and Polacco JC. Arginase-negative mutants of Arabidopsis exhibit increased nitric oxide signaling in root development. Plant Physiology 2008;147(4):1936-1946.

Carlini CR and Polacco JC. Toxic properties of urease. Crop Science 2008;48(5):1665-1672.

Bilyeu KD, Zeng P, Coello P, Zhang ZJ, Krishnan HB, Bailey A, Beuselinck PR and Polacco JC. Quantitative conversion of phytate to inorganic phosphorus in soybean seeds expressing a bacterial phytase. Plant Physiology 2008;146(2):468-477.

Todd, CD, Tipton P, Blevins DG, Pineda M, Piedras P, Polacco JC (2006) Update on ureide degradation in legumes. J Exp Botany 57: 5-12

Lombardo MC, Graziano M, Polacco JC, Lamattina L (2006) Nitric oxide functions as a positive regulator of root hair development. Plant Signaling & Behavior 1: 28-33

Todd CD, Polacco JC (2006) AtAAH, an allantoate amidohydrolase from Arabidopsis thaliana. Planta 223: 1108 - 1113

Palmieri L, Todd CD, Arrigoni R, Hoyos ME, Santoro A, Polacco JC (2006) Arabidopsis mitochondria have two basic amino acid transporters with partially overlapping specificities and differential expression in seedling development. Biochimica et Biophysica Acta 1757: 1277-1283

Todd CD, Polacco JC. Soybean cultivars 'Williams 82' and 'Maple Arrow' produce both urea and ammonia during ureide degradation. J Exp Bot 2004;55: 867-877.

Todd, CD, Peiyu Z, Rodriguez Huete AM, Hoyos ME, Polacco JC. Transcripts of MYB-like genes respond to phosphorus and nitrogen deprivation in Arabidopsis. Planta 2004;219: 1003-1009.

Jeff Reneker J, Shyu C-R, Zeng, P, Polacco JC, Gassmann W. ACMES: Fast multiple-genome searches for short repeat sequences with concurrent cross-species information retrieval. Nuc Acid Res 2004;32:W649-W653

Vodkin LO, Khanna A, Shealy R, Clough SJ, Delkin OG, Philip R, Zabala G, Thibaud-Nissen F, Sidarous M, Stromvik MV, Shoop E, Schmidt C, Retzel E, Erpelding J, Shoemaker RC, Rodriguez-Huete A, Polacco JC, Coryell V, Keim P, Gong G, Liu L, Pardinas J, Schweitzer P. Microarrays for global expression using 27,500 sequenced cDNAs representing an array of developmental stages and physiological conditions of the soybean plant. Online, Bio Med Cent Genomics 2004;5, 73