The spectrum of low molecular weight alpha-amylase/protease inhibitor genes expressed in the US bread wheat Butte 86

Authors: Altenbach, Susan; Vensel, William; Dupont, Frances

Submitted to: BMC Research Notes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2011
Publication Date: 7/20/2011
Citation: Altenbach, S.B., Vensel, W.H., Dupont, F.M. 2011. The spectrum of low molecular weight alpha-amylase/protease inhibitor genes expressed in the US bread wheat Butte 86. BMC Research Notes. 4:242.

Interpretive Summary: The alpha amylase/protease inhibitors are a group of small proteins accumulated in wheat kernels that protect the grain from insects, mites and other predators. These proteins are present in reasonably large quantities in wheat flour and are a major cause of baker’s asthma, an important occupational allergy that affects millers and bakers. In addition, some of these proteins have been implicated in human food allergies. To better understand the role of these proteins in human allergies, the complement of alpha amylase/protease inhibitor genes expressed in the US commercial wheat cultivar Butte 86 was investigated. Eighteen different gene sequences were identified and the relative expression levels of the genes were evaluated. Four of the gene sequences encoded proteins that were substantially different from alpha amylase/protease inhibitors reported previously. Sixteen gene sequences were unequivocally associated with individual proteins present in the flour. Information on the spectrum of alpha amylase/protease inhibitors expressed in a single wheat cultivar is central to understanding the importance of these proteins in both plant defense mechanisms and human allergies.

Technical Abstract: The complement of genes encoding alpha-amylase/protease inhibitors expressed in Triticum aestivum cv. Butte 86 was characterized by transcript and proteomic analysis. Coding sequences for 18 distinct proteins were identified among a collection of expressed sequence tags (ESTs) from Butte 86 developing grain. These included two monomeric (WMAI), four dimeric (WDAI), and six tetrameric (WTAI) inhibitors of exogenous alpha-amylases, two inhibitors of endogenous alpha-amylase (WASI), three putative trypsin inhibitors (CMx) and one putative chymotrypsin inhibitor (WCI). Most of the encoded proteins were identical or very similar to proteins in NCBI. Sequences not reported previously included variants of the WTAI inhibitor CM3 and three CMx inhibitors. Based on numbers of ESTs, Butte 86 genes encoding WTAI-CM3-Bu-1, WMAI-Bu-1 and WTAI-CM16-Bu-1 were the most highly expressed in developing grain and were expressed at levels comparable to alpha gliadins. Sixteen coding sequences, including the three CMx sequences, were unequivocally associated with specific protein spots identified by tandem mass spectrometry (MS/MS) in a previous proteomic analysis of total wheat flour from Butte 86. Information on the spectrum of alpha-amylase/protease inhibitors expressed in a single wheat cultivar is central to understanding the importance of these proteins in both plant defense mechanisms and human allergies.