Xijun Chen;Xiaowei Liu;Si-min Zuo;Yulong Ma;Tong YunHui;Pan X;Jing X

Key Laboratory of Plant Functional Genomics of Ministry of Education / Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, Yangzhou University, Yangzhou 225009, China;Horticulture and Plant Protection College, Yangzhou University, Yangzhou 225009, China;Horticulture and Plant Protection College, Yangzhou University, Yangzhou 225009, Chin

Ospgip1 gene;polygalacturonase-inhibiting protein;prokaryotic expression;bioinformatic analysis;rice;Rhizoctonia solan

Using the reference sequences of pgip genes in GenBank, a fragment of 930 bp covering the open reading frame (ORF) of rice Ospgip1 (Oryza sativa polygalacturonase-inhibiting protein 1) was amplified. The prokaryotic expression product of the gene inhibited the growth of Rhizoctonia solani, the causal agent of rice sheath blight, and reduced its polygalacturonase activity. Bioinformatic analysis showed that OsPGIP1 is a hydrophobic protein with a molecular weight of 32.8 kDa and an isoelectric point (pI) of 7.26. The protein is mainly located in the cell wall of rice, and its signal peptide cleavage site is located between the 17th and 18th amino acids. There are four cysteines in both the N- and C-termini of the deduced protein, which can form three disulfide bonds (between the 56th and 63rd, the 278th and 298th, and the 300th and 308th amino acids). The protein has a typical leucine-rich repeat (LRR) domain, and its secondary structure comprises alpha-helices, beta-sheets and irregular coils. Compared with polygalacturonase-inhibiting proteins (PGIPs) from other plants, the 7th LRR is absent in OsPGIP1. The nine LRRs could form a cleft that might associate with proteins from pathogenic fungi, such as polygalacturonase.