1clv
From Proteopedia
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YELLOW MEAL WORM ALPHA-AMYLASE IN COMPLEX WITH THE AMARANTH ALPHA-AMYLASE INHIBITOR
Overview
BACKGROUND: alpha-Amylases constitute a family of enzymes that catalyze, the hydrolysis of alpha-D-(1,4)-glucan linkages in starch and related, polysaccharides. The Amaranth alpha-amylase inhibitor (AAI) specifically, inhibits alpha-amylases from insects, but not from mammalian sources. AAI, is the smallest proteinaceous alpha-amylase inhibitor described so far and, has no known homologs in the sequence databases. Its mode of inhibition of, alpha-amylases was unknown until now. RESULTS: The crystal structure of, yellow meal worm alpha-amylase (TMA) in complex with AAI was determined at, 2.0 A resolution. The overall fold of AAI, its three-stranded twisted beta, sheet and the topology of its disulfide bonds identify it as a, knottin-like protein. The inhibitor binds into the active-site groove of, TMA, blocking the central four sugar-binding subsites. Residues from two, AAI segments target the active-site residues of TMA. A comparison of the, TMA-AAI complex with a modeled complex between porcine pancreatic, alpha-amylase (PPA) and AAI identified six hydrogen bonds that can be, formed only in the TMA-AAI complex. CONCLUSIONS: The binding of AAI to TMA, presents a new inhibition mode for alpha-amylases. Due to its unique, specificity towards insect alpha-amylases, AAI might represent a valuable, tool for protecting crop plants from predatory insects. The close, structural homology between AAI and 'knottins' opens new perspectives for, the engineering of various novel activities onto the small scaffold of, this group of proteins.
About this Structure
1CLV is a Protein complex structure of sequences from Tenebrio molitor with CA and CL as ligands. Active as Alpha-amylase, with EC number 3.2.1.1 Full crystallographic information is available from OCA.
Reference
Specific inhibition of insect alpha-amylases: yellow meal worm alpha-amylase in complex with the amaranth alpha-amylase inhibitor at 2.0 A resolution., Pereira PJ, Lozanov V, Patthy A, Huber R, Bode W, Pongor S, Strobl S, Structure. 1999 Sep 15;7(9):1079-88. PMID:10508777
Page seeded by OCA on Tue Nov 20 12:34:06 2007
