Cloning and expression of a LMW-i glutenin gene

Endosperm-specific low-molecular-weight (LMW) glutenins are an important component of the polymeric gluten and, as such, play a key role in end-use functionality. Reports of N-terminal amino sequences of LMW glutenin fractions related that they have either a methionine or a serine residue at the first position of the mature peptide. These subunits were therefore called LMW-m and LMW-s type glutenins. A gene that is predicted to encode a LMW glutenin subunit having an isoleucine amino acid residue at position one of the mature protein was amplified and cloned from extra strong bread wheat cultivar Glenlea (pGH3.1). The predicted N-terminal sequence of this gene is truncated as compared to the m-type and s-type. The gene still codes for the expected number of eight cysteine residues which are all located in the C-terminal region. The propose to call it LMW-i based on the same nomenclature. Analysis of 277 doubled haploid lines derived from a single cross showed perfect co-segregation of the cloned PCR fragment with a rare LMW glutenin called LMW-50. The gene was subcloned in an expression vector and the protein was suppressed in E. coli. Western blot analysis using a prolamin-specific monoclonal antibody confirmed the co-migrational of the cloned protein with LMW-50 from Glenlea. (C) 2001 Academic Press.