Characterization of the HMW glutenin subunits from Aegilops searsii and identification of a novel variant HMW glutenin subunit.
High molecular weight (HMW) glutenin subunits are conserved seed storage proteins in wheat and related species. Here we describe a more detailed characterization of the HMW glutenin subunits from Aegilops searsii, which is diploid and contains the S(s) genome related to the S genome of Aegilops speltoides and the A, B and D genomes of hexaploid wheat. SDS-PAGE experiments revealed two subunits (one x and one y) for each of the nine Ae. searsii accessions analyzed, indicating that the HMW glutenin subunit gene locus of Ae. searsii is similar to the Glu-1 locus found in wheat in containing both x and y genes. The primary structure of the four molecularly cloned subunits (from two Ae. searsii accessions) was highly similar to that of the previously reported x and y subunits. However, in one accession (IG49077), the last 159 residues of the x subunit (1S(s)x49077), which contained the sequence element GHCPTSPQQ, were identical to those of the y subunit (1S(s)y49077) from the same accession. Consequently, 1S(s)x49077 contains an extra cysteine residue located at the C-terminal part of its repetitive domain, which is novel compared to the x-type subunits reported so far. Based on this and previous studies, the structure and expression of the Glu-1 locus in Ae. searsii is discussed. A hypothesis on the genetic mechanism generating the coding sequence for the novel 1S(s)x49077 subunit is presented.
Sun
Xia
X
The State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Hu
Shanglian
S
Liu
Xin
X
Qian
Weiqiang
W
Hao
Shanting
S
Zhang
Aimin
A
Wang
Daowen
D
D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D014644:Genetic Variation; D005983:Glutens / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D010802:Phylogeny; D006109:Poaceae / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein
D021122:Protein Subunits; D005983:Glutens; C037302:glutenin