NAI1 gene encodes a basic-helix-loop-helix-type putative transcription factor that regulates the formation of an endoplasmic reticulum-derived structure, the ER body.
Plant cells develop various types of endoplasmic reticulum (ER)-derived structures with specific functions. ER body, an ER-derived compartment in Arabidopsis thaliana, is a spindle-shaped structure. The NAI1 gene regulates the development of ER bodies because mutation of NAI1 abolishes the formation of ER bodies. To better understand the role of NAI1, we cloned the NAI1 gene using a positional cloning strategy. The nai1-1 mutant had a single nucleotide change at an intron acceptor site of At2g22770 (NAI1 gene). Because of this mutation, aberrant splicing of NAI1 mRNA occurs in the nai1-1 mutant. NAI1 encodes a transcription factor that has a basic-helix-loop-helix (bHLH) domain. Transient expression of NAI1 induced ER bodies in the nai1-1 mutant. Two-dimensional electrophoresis and RT-PCR analyses showed that a putative lectin was depressed at both the mRNA and protein levels in nai1 mutants, as was a beta-glucosidase (PYK10). Our results provide direct evidence that a bHLH protein plays a role in the formation of ER bodies.
Matsushima
Ryo
R
Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502 Japan.
Fukao
Yoichiro
Y
Nishimura
Mikio
M
Hara-Nishimura
Ikuko
I
D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D032461:Chromosomes, Plant / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D015536:Down-Regulation; D015180:Electrophoresis, Gel, Two-Dimensional; D004721:Endoplasmic Reticulum / Q000737:chemistry / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005959:Glucosidases / Q000378:metabolism; D018257:Helix-Loop-Helix Motifs; D037102:Lectins / Q000737:chemistry; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation / Q000235:genetics; D020161:Physical Chromosome Mapping; D012326:RNA Splicing / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics; D005644:alpha-L-Fucosidase / Q000378:metabolism
D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D037102:Lectins; D012333:RNA, Messenger; C036483:T-DNA; D014157:Transcription Factors; D005959:Glucosidases; D005644:alpha-L-Fucosidase