Transcriptional control of lignin biosynthesis by tobacco LIM protein.
Lignin is a complex phenolic plant polymer that is essential for mechanical support, defense, and water transport in higher plants. The AC-rich motif, Pal-box is an important cis-acting element for gene expression in phenylpropanoid biosynthesis. We isolated a cDNA clone (Ntlim1) encoding a Pal-box binding protein by Southwestern screening. The deduced amino acid sequence of Ntlim1 is highly similar to members of the LIM protein family that contain a zinc finger motif. Moreover, Ntlim1 had a specific DNA-binding ability and transiently activated transcription of a beta-glucuronidase reporter gene driven by the Pal-box sequence. The results of transient expression assays with tobacco cultured cells showed that fusion proteins between GFP and Ntlim1 can enter nuclei. Transgenic tobacco plants with antisense Ntlim1 showed low levels of transcripts from some key phenylpropanoid pathway genes such as phenylalanine ammonia-lyase, hydroxycinnamate CoA ligase and cinnamyl alcohol dehydrogenase. Furthermore, a greater than 20% reduction in lignin content was observed in transgenic tobacco with antisense Ntlim1.
Kawaoka
A
A
Nippon Paper Industries Co., Ltd, Pulp and Paper Research Laboratory, 5-21-1, Oji, Kita-ku, Tokyo 114-0002, Japan. akiyoshi.kawaoka@nifty.ne.jp
Ebinuma
H
H
D000595:Amino Acid Sequence; D001483:Base Sequence; D018076:DNA, Complementary; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D060588:LIM Domain Proteins; D008031:Lignin / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D010940:Plant Proteins; D010947:Plants, Toxic; D014026:Nicotiana / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology*
D018076:DNA, Complementary; D060588:LIM Domain Proteins; C434801:Ntlim1 protein, Nicotiana tabacum; D010940:Plant Proteins; D014157:Transcription Factors; D008031:Lignin