Hybrid Rubisco with Complete Replacement of Rice Rubisco Small Subunits by Sorghum Counterparts Confers C4 Plant-like High Catalytic Activity  

作　　者：Hiroyoshi Matsumura Keita Shiomi Akito Yamamoto Yuri Taketani Noriyuki Kobayashi Takuya Yoshizawa Shun-ichi Tanaka Hiroki Yoshikawa Masaki Endo Hiroshi Fukayama 

机构地区：[1]Department of Biotechnology,College of Life Sciences,Ritsumeikan University,1-1-1 Noji-Higashi,Kusatsu 525-8577,Japan [2]Graduate School of Agricultural Science,Kobe University,1-1 Rokkodai-tyou,Nada-ku,Kobe 657-8501,Japan [3]Faculty of Agriculture,Kobe University,1-1 Rokkodai-tyou,Nada-ku,Kobe 657-8501,Japan [4]Division of Applied Genetics,Institute of Agrobiological Sciences,National Agriculture and Food Research Organization,1-2 Owashi,Tsukuba 305-8634,Japan [5]Department of Biomolecular Chemistry,Kyoto Prefectural University,Hangi-cho,Shimogamo,Sakyo-ku,Kyoto 606-8522,Japan

出　　处：《Molecular Plant》2020年第11期1570-1581,共12页分子植物（英文版）

基　　金：Grants-in-Aid for Scientific Research(17H05732,18K06094,19H04735,and 19K07582 to H.M.,24580021 and 15H04443 to H.F.);the Program for the Third-Phase R-GIRO。

摘　　要：Photosynthetic rate at the present atmospheric condition is limited by the CO2-fixing enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase(Rubisco)because of its extremely low catalytic rate(kcat)and poor affinity for C02(Kc)and specificity for CO2(Sc/O).Rubisco in C4 plants generally shows higher k cat than that in C3 plants.Rubisco consists of eight large subunits and eight small subunits(RbcS).Previously,the chimeric incorporation of sorghum C4-type RbcS significantly increased the k cat of Rubisco in a C3 plant,rice.In this study,we knocked out rice RbcS multigene family using the CRISPR-Cas9 technology and completely replaced rice RbcS with sorghum RbcS in rice Rubisco.Obtained hybrid Rubisco showed almost C4 plant-like catalytic properties,i.e.,higher kcai,higher Kc,and lower Sc/O.Transgenic lines expressing the hybrid Rubisco accumulated reduced levels of Rubisco,whereas they showed slightly but significantly higher photosynthetic capacity and similar biomass production under high C 02 condition compared with wild-type rice.High-resolution crystal structural analysis of the wild-type Rubisco and hybrid Rubisco revealed the structural differences around the central pore of Rubisco and the pC-pD hairpin in RbcS.We propose that such differences,particularly in the pC-pD hairpin,may impact the flexibility of Rubisco catalytic site and change its catalytic properties.

关 键 词：CRISPR-Cas9 C4 plant PHOTOSYNTHESIS RICE RUBISCO 

分 类 号：S511[农业科学—作物学]