Similarities of omega gliadins from Triticum urartu to those encoded on chromosome 1A of hexaploid wheat and evidence for their post-translational processing.
The omega-gliadins encoded on chromosome 1 of the A genome were purified from Triticum aestivum L. (2n=6 x=42, AABBDD) cv. Butte86, nullisomic 1D-tetrasomic 1A of cv. Chinese Spring (CS N1DT1A), and the diploid T. urartu (2n=2 x=14, AA ). Reverse-phase high-performance liquid chromatography combined with sodium dodecyl sulfate-polyacrylamide gel electrophoresis of gliadin extracts from CS nullisomic-tetrasomic (NT) lines confirmed the assignment to chromosome 1A. The purified omega-gliadins were characterized by mass spectrometry and N-terminal sequencing. The 1A-encoded omega-gliadins were smaller than 1B- or 1D-encoded omega-gliadins. The N-terminal amino acid sequences for 1A omega-gliadin mature peptides were nearly identical to those for the T. urartu omega-gliadins and were more similar to 1D omega-gliadin sequences than to sequences for T. monococum omega-gliadins, barley C-hordeins, or rye omega-secalins. They diverged greatly from the N-terminal sequences for the 1B omega-gliadins. The data suggest that T. urartu is the A-genome donor, and that post-translational cleavage by an asparaginyl endoprotease produces those omega-gliadins with N-terminal sequences beginning with KEL.
DuPont
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USDA Agricultural Research Service, 800 Buchanan Street, Albany, CA 94710, USA. fmd@pw.usda.gov
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D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D032461:Chromosomes, Plant / Q000235:genetics*; D004591:Electrophoresis, Polyacrylamide Gel; D005903:Gliadin / Q000235:genetics / Q000378:metabolism*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D011123:Polyploidy; D011499:Protein Processing, Post-Translational / Q000235:genetics*; D020539:Sequence Analysis, Protein; D014908:Triticum / Q000235:genetics*
D005903:Gliadin