Cloning and Expression of Low Molecular Weight Glutenin Genes from the Chinese Elite Wheat Cultivar “Xiaoyan 54”

Abstract

AbstractThe low molecular weight (LMW) glutenin subunits account for 40% of wheat gluten protein content by mass and these proteins are considered to significantly affect dough quality characteristics. Five new full‐length LMW glutenin genes (designated LMW‐5, LMW‐7, LMW‐42, LMW‐58, and LMW‐34) were isolated from the Chinese elite wheat cultivar “Xiaoyan 54” by PCR amplification of genomic DNA using a pair of degenerate primers designed from the conserved sequences of the N‐ and C‐terminal regions of published LMW glutenin genes. Deduced amino acid sequence analysis showed that LMW‐5 belongs to the LMW‐i type genes and that the other four belong to LMW‐m type genes. Sequence comparisons revealed that point mutations occasionally occurred in signal peptide and N‐terminus domains and often existed in domain III and domain V. Small insertions and deletions are represented in the repetitive domain. There is a stop codon after amino acid position 110 in the repetitive domain of LMW‐34, indicating that it is a pseudogene. The other four genes have complete open reading frames and the putative mature regions of these genes were subcloned into pET‐30a expression vector and successfully expressed in Escherichia coli. Protein sodium dodecyl sulfate‐polyacrylamide gel electro‐phoresis analysis showed that all proteins expressed in E. coli by the four genes could be related to B‐group LMW glutenin subunits of wheat.(Managing editor: Li‐Hui Zhao)