A new chitinase-like xylanase inhibitor protein (XIP) from coffee (<it>Coffea arabica</it>) affects Soybean Asian rust (<it>Phakopsora pachyrhizi</it>) spore germination

• Main Authors: Mehta Angela, Filho Edivaldo XF, Fitches Elaine, Price Daniel, Oliveira-Neto Osmundo B, Silva Marilia S, Moreira Leonora RS, Seixas Claudine DS, Godoy Claudia V, Santana Celso G, Vasconcelos Erico AR, Gatehouse John A, Grossi-De-Sa Maria F
• Format: Article
• Language: English
• Published: BMC 2011-02-01
• Series: BMC Biotechnology
• Online Access: http://www.biomedcentral.com/1472-6750/11/14

<p>Abstract</p> <p>Background</p> <p>Asian rust (<it>Phakopsora pachyrhizi</it>) is a common disease in Brazilian soybean fields and it is difficult to control. To identify a biochemical candidate with potential to combat this disease, a new chitinase-like xylanase inhibitor protein (XIP) from coffee (<it>Coffea arabica</it>) (CaclXIP) leaves was cloned into the pGAPZα-B vector for expression in <it>Pichia pastoris</it>.</p> <p>Results</p> <p>A cDNA encoding a chitinase-like xylanase inhibitor protein (XIP) from coffee (<it>Coffea arabica</it>) (CaclXIP), was isolated from leaves. The amino acid sequence predicts a (β/α)₈topology common to Class III Chitinases (glycoside hydrolase family 18 proteins; GH18), and shares similarity with other GH18 members, although it lacks the glutamic acid residue essential for catalysis, which is replaced by glutamine. CaclXIP was expressed as a recombinant protein in <it>Pichia pastoris</it>. Enzymatic assay showed that purified recombinant CaclXIP had only residual chitinolytic activity. However, it inhibited xylanases from <it>Acrophialophora nainiana </it>by approx. 60% when present at 12:1 (w/w) enzyme:inhibitor ratio. Additionally, CaclXIP at 1.5 μg/μL inhibited the germination of spores of <it>Phakopsora pachyrhizi </it>by 45%.</p> <p>Conclusions</p> <p>Our data suggests that CaclXIP belongs to a class of naturally inactive chitinases that have evolved to act in plant cell defence as xylanase inhibitors. Its role on inhibiting germination of fungal spores makes it an eligible candidate gene for the control of Asian rust.</p>