Santagati Vito Davide, Sestili Francesco, Lafiandra Domenico, D'Ovidio Renato, Rogniaux Helene, Masci Stefania
DAFNE, Department of Agricultural and Forestry Sciences, Tuscia University, Via San Camillo de Lellis snc, Viterbo, 01100, Italy.
INRA, UR1268 Biopolymers Interactions Assemblies, Rue de la Géraudière, Nantes Cedex 3, 44316, France.
J Mass Spectrom. 2016 Jul;51(7):512-7. doi: 10.1002/jms.3776.
Wheat high molecular weight glutenin subunit variation is important because of its great influence on glutenin polymer structure, that is related to dough technological properties. Among the different subunits, the pair Bx20 and By20 is known to have a negative effect on quality, but the reasons are not clear: Bx20 has two cysteines, which theoretically make this subunit a chain extender of the glutenin polymer, just like the other Bx subunits, showing four cysteines, two of which should be involved in intra-molecular disulfide bonds. By20 has never been characterized so far at molecular level. Here we report the nucleotide sequences of Bx20 and By20 genes isolated from the durum wheat cultivar 'Lira 45' and the validation of the corresponding deduced amino acid sequences by using MALDI-TOF and LC-MS/MS. Four nucleotide differences were identified in the Bx20 gene with respect to the deduced sequence present in NCBI, causing two amino acid substitutions. For the By20 subunit, nucleotide and amino acid sequences revealed a great similarity to By15, both at gene and protein levels, showing five nucleotide changes generating two amino acid differences. No evidence of post-translational modifications has been found. Hypotheses are formulated in regard to relationships with technological quality. Copyright © 2016 John Wiley & Sons, Ltd.
小麦高分子量谷蛋白亚基的变异很重要，因为它对谷蛋白聚合物结构有很大影响，而谷蛋白聚合物结构与面团工艺特性相关。在不同的亚基中，已知Bx20和By20这一对亚基对品质有负面影响，但原因尚不清楚：Bx20有两个半胱氨酸，理论上这使得该亚基成为谷蛋白聚合物的链延伸剂，就像其他Bx亚基一样，显示有四个半胱氨酸，其中两个应该参与分子内二硫键。到目前为止，By20在分子水平上从未被表征过。在此，我们报道了从硬粒小麦品种‘Lira 45’中分离出的Bx20和By20基因的核苷酸序列，并通过基质辅助激光解吸电离飞行时间质谱（MALDI-TOF）和液相色谱-串联质谱（LC-MS/MS）对相应推导的氨基酸序列进行了验证。相对于NCBI中存在的推导序列，在Bx20基因中鉴定出四个核苷酸差异，导致两个氨基酸替换。对于By20亚基，核苷酸和氨基酸序列在基因和蛋白质水平上都显示出与By15有很大的相似性，有五个核苷酸变化产生两个氨基酸差异。未发现翻译后修饰的证据。针对与工艺品质的关系提出了假设。版权所有© 2016约翰威立父子有限公司。
