Arabidopsis NF-YB subunits LEC1 and LEC1-LIKE activate transcription by interacting with seed-specific ABRE-binding factors.
LEAFY COTYLEDON 1 (LEC1) plays vital roles in the regulation of seed maturation in Arabidopsis. LEC1 encodes a homolog of yeast HAP3 or mammalian NF-YB/CBF-A subunit of trimeric CCAAT binding factor (CBF). Among the nine paralogs of NF-YB in Arabidopsis, LEC1-LIKE (L1L) is most closely related to LEC1, and can complement the lec1 mutation when expressed under the control of the LEC1 promoter. Although the nature of the B3-type seed maturation regulators as transcription factors have been investigated, knowledge of the molecular action of LEC1 is limited. When co-expressed with NF-YC2 in the presence of ABA, we found that LEC1 or L1L, but not other NF-YBs, activated the promoter of CRUCIFERIN C (CRC), which encodes a seed storage protein. However, additional expression of an NF-YA subunit interfered with the activation. The LEC1/L1L-[NF-YC2] activation depended on ABA-response elements present in the promoter, which led to the finding that LEC1/L1L-[NF-YC2] can strongly activate the CRC promoter in the absence of ABA when co-expressed with a seed-specific ABA-response element (ABRE)-binding factor, bZIP67. Functional coupling of LEC1/L1L-[AtNF-YC2] and bZIP67 was also observed in the regulation of sucrose synthase 2 (SUS2). Immunoprecipitation experiments revealed that L1L and bZIP67 formed a protein complex in vivo. These results demonstrate a novel plant-specific mechanism for NF-Y subunit function that enables LEC1 and L1L to regulate a defined developmental network.
Yamamoto
Akiko
A
Bioscience and Biotechnology Center, Nagoya University, Chikusa-ku, Nagoya, Japan.
Kagaya
Yasuaki
Y
Toyoshima
Ryoko
R
Kagaya
Michiko
M
Takeda
Shin
S
Hattori
Tsukaho
T
D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D016254:Mutagenesis, Insertional; D011401:Promoter Regions, Genetic; D018749:RNA, Plant / Q000235:genetics; D012097:Repressor Proteins / Q000378:metabolism; D020218:Response Elements; D012639:Seeds / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D022762:CCAAT-Enhancer-Binding Proteins; C113191:LEC1 protein, Arabidopsis; D018749:RNA, Plant; D012097:Repressor Proteins; C500132:Zip67 protein, Arabidopsis; D000040:Abscisic Acid