title: Subtle Regulation of Potato Acid Invertase Activity by a Protein Complex of Invertase, Invertase Inhibitor, and SUCROSE NONFERMENTING1-RELATED PROTEIN KINASE.
abstract: Slowing down cold-induced sweetening (CIS) of potato (Solanum tuberosum) tubers is of economic importance for the potato industry to ensure high-quality products. The conversion of sucrose to reducing sugars by the acid invertase StvacINV1 is thought to be critical for CIS. Identification of the specific StvacINV1 inhibitor StInvInh2B and the α- and β-subunits of the interacting protein SUCROSE NONFERMENTING1-RELATED PROTEIN KINASE from the wild potato species Solanum berthaultii (SbSnRK1) has led to speculation that invertase activity may be regulated via a posttranslational mechanism that remains to be elucidated. Using bimolecular fluorescence complementation assays, this study confirmed the protein complex by pairwise interactions. In vitro kinase assays and protein phosphorylation analysis revealed that phosphorylation of SbSnRK1α is causal for StvacINV1 activity and that its active form blocks the inhibition of StInvInh2B by SbSnRK1β, whereas its inactive form restores the function of SbSnRK1β that prevents StInvInh2B from repressing StvacINV1. Overexpression of SbSnRK1α in CIS-sensitive potato confirmed that SbSnRK1α has significant effects on acid invertase-associated sucrose degradation. A higher level of SbSnRK1α expression was accompanied by elevated SbSnRK1α phosphorylation, reduced acid invertase activity, a higher sucrose-hexose ratio, and improved chip color. Our results lend new insights into a subtle regulatory mode of invertase activity and provide a novel approach for potato CIS improvement.
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, National Center for Vegetable Improvement (Central China), Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, People's Republic of China (Y.L., T.L., J.L., X.L., Y.O., H.Z., M.L., B.S., C.X.); andBiochemistry Division, Department of Biology, Friedrich-Alexander-University Erlangen-Nuernberg, 91058 Erlangen, Germany (U.S.).
authors.forename: Yuan
authors.identifier: http://orcid.org/0000-0002-2904-6390
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, National Center for Vegetable Improvement (Central China), Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, People's Republic of China (Y.L., T.L., J.L., X.L., Y.O., H.Z., M.L., B.S., C.X.); andBiochemistry Division, Department of Biology, Friedrich-Alexander-University Erlangen-Nuernberg, 91058 Erlangen, Germany (U.S.).
authors.forename: Tengfei
authors.initials: T
authors.lastname: Liu
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, National Center for Vegetable Improvement (Central China), Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, People's Republic of China (Y.L., T.L., J.L., X.L., Y.O., H.Z., M.L., B.S., C.X.); andBiochemistry Division, Department of Biology, Friedrich-Alexander-University Erlangen-Nuernberg, 91058 Erlangen, Germany (U.S.).
authors.forename: Jun
authors.identifier: http://orcid.org/0000-0002-4012-3596
authors.initials: J
authors.lastname: Liu
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, National Center for Vegetable Improvement (Central China), Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, People's Republic of China (Y.L., T.L., J.L., X.L., Y.O., H.Z., M.L., B.S., C.X.); andBiochemistry Division, Department of Biology, Friedrich-Alexander-University Erlangen-Nuernberg, 91058 Erlangen, Germany (U.S.).
authors.forename: Xun
authors.identifier: http://orcid.org/0000-0002-4873-6610
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, National Center for Vegetable Improvement (Central China), Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, People's Republic of China (Y.L., T.L., J.L., X.L., Y.O., H.Z., M.L., B.S., C.X.); andBiochemistry Division, Department of Biology, Friedrich-Alexander-University Erlangen-Nuernberg, 91058 Erlangen, Germany (U.S.).
authors.forename: Yongbin
authors.identifier: http://orcid.org/0000-0002-4347-7146
authors.initials: Y
authors.lastname: Ou
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, National Center for Vegetable Improvement (Central China), Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, People's Republic of China (Y.L., T.L., J.L., X.L., Y.O., H.Z., M.L., B.S., C.X.); andBiochemistry Division, Department of Biology, Friedrich-Alexander-University Erlangen-Nuernberg, 91058 Erlangen, Germany (U.S.).
authors.forename: Huiling
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, National Center for Vegetable Improvement (Central China), Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, People's Republic of China (Y.L., T.L., J.L., X.L., Y.O., H.Z., M.L., B.S., C.X.); andBiochemistry Division, Department of Biology, Friedrich-Alexander-University Erlangen-Nuernberg, 91058 Erlangen, Germany (U.S.).
authors.forename: Meng
authors.initials: M
authors.lastname: Li
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, National Center for Vegetable Improvement (Central China), Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, People's Republic of China (Y.L., T.L., J.L., X.L., Y.O., H.Z., M.L., B.S., C.X.); andBiochemistry Division, Department of Biology, Friedrich-Alexander-University Erlangen-Nuernberg, 91058 Erlangen, Germany (U.S.).
authors.forename: Uwe
authors.identifier: http://orcid.org/0000-0003-1835-5339
authors.initials: U
authors.lastname: Sonnewald
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, National Center for Vegetable Improvement (Central China), Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, People's Republic of China (Y.L., T.L., J.L., X.L., Y.O., H.Z., M.L., B.S., C.X.); andBiochemistry Division, Department of Biology, Friedrich-Alexander-University Erlangen-Nuernberg, 91058 Erlangen, Germany (U.S.) songbotao@mail.hzau.edu.cn xiech@mail.hzau.edu.cn.
authors.forename: Botao
authors.initials: B
authors.lastname: Song
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, National Center for Vegetable Improvement (Central China), Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, People's Republic of China (Y.L., T.L., J.L., X.L., Y.O., H.Z., M.L., B.S., C.X.); andBiochemistry Division, Department of Biology, Friedrich-Alexander-University Erlangen-Nuernberg, 91058 Erlangen, Germany (U.S.) songbotao@mail.hzau.edu.cn xiech@mail.hzau.edu.cn.
authors.forename: Conghua
authors.identifier: http://orcid.org/0000-0002-6988-7776
authors.initials: C
authors.lastname: Xie
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D018506:Gene Expression Regulation, Plant; D006601:Hexoses / Q000378:metabolism; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D035281:Plant Tubers / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D011198:Solanum tuberosum / Q000235:genetics / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism; D043324:beta-Fructofuranosidase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D006601:Hexoses; D010940:Plant Proteins; D013395:Sucrose; D017346:Protein Serine-Threonine Kinases; D043324:beta-Fructofuranosidase