The transcription factor CONSTANS (CO) integrates day-length information to induce the expression of florigen FLOWERING LOCUS T (FT) in Arabidopsis. We recently reported that the C-terminal CCT domain of CO forms a complex with NUCLEAR FACTOR-YB/YC to recognize multiple cis-elements in the FT pro-moter, and the N-terminal tandem B-box domains form a homomultimeric assembly. However, the mechanism and biological function of CO multi-merization remained unclear. Here, we report that CO takes on a head-to-tail oligomeric configuration via its B-boxes to mediate FT activation in long days. The crystal structure of B-boxesCO reveals a closely connected tandem B-box fold forming a continuous head-to-tail assembly through unique CDHH zinc fingers. Mutating the key residues involved in CO oligomerization resulted in a non-functional CO, as evidenced by the inability to rescue co mutants. By contrast, a transgene encoding a human p53-derived tetrameric peptide in place of the B-boxesCO rescued co mutant, emphasizing the essential role of B-boxesCO-mediated oligomerization. Furthermore, we found that the four TGTG-bearing cis-elements in FT proximal promoter are required for FT activation in long days. Our results suggest that CO forms a multimer to bind to the four TGTG motifs in the FT promoter to mediate FT activation.

Xiaolin Zeng;Xinchen Lv;Rui Liu;Hang He;Shiqi Liang;Lixian Chen;Fan Zhang;Liu Chen;Yuehui He;Jiamu Du

Peking-Tsinghua Center for Life Sciences,School of Advanced Agricultural Sciences,Peking University,Beijing 100871,China;National Key Laboratory of Plant Molecular Genetics&Shanghai Center for Plant Stress Biology,Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences,Shanghai 201602,China;Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes,Institute of Plant and Food Science,Department of Biology,School of Life Sciences,Southern University of Science and Technology,Shenzhen 518055,China;Peking University Institute of Advanced Agricultural Sciences,Weifang 261000,China

植物学报（英文版）

[1]Xiaolin Zeng;Xinchen Lv;Rui Liu;Hang He;Shiqi Liang;Lixian Chen;Fan Zhang;Liu Chen;Yuehui He;Jiamu Du-.Molecular basis of CONSTANS oligomerization in FLOWERING LOCUS T activation)[J].植物学报（英文版）,2022(03):731-740

florigen,NUCLEAR,homomultimeric,boxesCO,CDHH,Mutating,tetrameric,multimer

Molecular,basis,CONSTANS,oligomerization,FLOWERING,LOCUS,activation,transcription,integrates,length,information,induce,expression,FT,Arabidopsis,We,recently,reported,that,terminal,CCT,forms,complex,FACTOR,YB,YC,recognize,multiple,cis,elements,tandem,domains,assembly,However,mechanism,biological,remained,unclear,Here,takes,head,tail,oligomeric,configuration,via,its,long,days,crystal,structure,reveals,closely,connected,fold,forming,continuous,through,unique,zinc,fingers,key,residues,involved,resulted,functional,evidenced,by,inability,mutants,By,contrast,transgene,encoding,human,p53,derived,peptide,place,rescued,emphasizing,essential,role,mediated,Furthermore,found,four,TGTG,bearing,proximal,promoter,are,required,Our,results,suggest,bind,motifs

0.505366