title: Identification of the isoamylase 3 gene in common wheat and its expression profile during the grain-filling period.
abstract: In higher plants, isoamylase-type starch debranching enzyme catalyzes the α-1,6-glucosidic linkages of glycogen and phytoglycogen. We cloned an isoamylase-type starch debranching enzyme ISA3 cDNA sequence (2883 bp), designated as TaISA3, from common wheat (Triticum aestivum), using the rapid amplification of cDNA ends method. The open reading frame of TaISA3 was found to have 2331 bp, and its deduced amino acid sequence was found to share high similarity with those of other gramineous plant ISA3 proteins. It contains a putative transit peptide (68 amino acids), N-terminus domain (107 amino acids), and a catalytic domain (173 amino acids). We extracted the expressed TaISA3 protein from Escherichia coli (BL21), and measured starch isoamylase activity. During the wheat grain-filling period, transcripts of the TaISA3 gene reached a maximum level at the early developmental stage, then declined, and increased again near the final maturation stage of the grain. We confirm that the ISA3 gene is present in common wheat; it appears to play a role in starch synthesis during early and late stages of the grain-filling period.
authors.affiliation: National Engineering Research Centre for Wheat, Key Laboratory of Physiology, Ecology and Genetic Improvement of Food Crops in Henan Province, Henan Agricultural University, Zhengzhou, China zkangg@163.com.
authors.forename: G Z
authors.initials: GZ
authors.lastname: Kang
authors.forename: G Q
authors.initials: GQ
authors.lastname: Liu
authors.forename: W
authors.initials: W
authors.lastname: Xu
authors.forename: Y J
authors.initials: YJ
authors.lastname: Zhu
authors.forename: C Y
authors.initials: CY
authors.lastname: Wang
authors.forename: H Q
authors.initials: HQ
authors.lastname: Ling
authors.forename: T C
authors.initials: TC
authors.lastname: Guo
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004790:Enzyme Induction; D004926:Escherichia coli; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D007517:Isoamylase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D017422:Sequence Analysis, DNA; D013213:Starch / Q000737:chemistry; D014908:Triticum / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D013213:Starch; D007517:Isoamylase