A new chitinase-like xylanase inhibitor protein (XIP) from coffee ( XXXX ) affects @entity1460 Asian rust ( @entity71934 ) spore germination.

@entity71934 @entity3264 @entity10056 @entity20760 @entity367 @entity1460 @entity3689
BACKGROUND: Asian rust ( @entity71934 ) is a common disease in Brazilian @entity1460 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 ( @entity20760 ) (CaclXIP) leaves was cloned into the pGAPZa-B vector for expression in @entity10056 . RESULTS: A cDNA encoding a chitinase-like xylanase inhibitor protein (XIP) from coffee ( @entity20760 ) (CaclXIP), was isolated from leaves. The @entity3689 sequence predicts a (b/a)8 topology common to Class III Chitinases (glycoside hydrolase family 18 proteins; GH18), and shares similarity with other GH18 members, although it lacks the @entity367 residue essential for catalysis, which is replaced by @entity3264 . CaclXIP was expressed as a recombinant protein in @entity10056 . Enzymatic assay showed that purified recombinant CaclXIP had only residual chitinolytic activity. However, it inhibited xylanases from Acrophialophora nainiana by approx. 60% when present at 12:1 (w/w) enzyme:inhibitor ratio. Additionally, CaclXIP at 1.5  g/ L inhibited the germination of spores of @entity71934 by 45%. CONCLUSIONS: 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.
