Proc Natl Acad Sci U S A. 2000 Nov 7;97(23):12902-7.

LEUNIG, a putative transcriptional corepressor that regulates AGAMOUS expression during flower development.

Source

Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA.

Abstract

Regulation of homeotic gene expression is critical for proper developmental patterns in both animals and plants. LEUNIG is a key regulator of the Arabidopsis floral homeotic gene AGAMOUS. Mutations in LEUNIG cause ectopic AGAMOUS mRNA expression in the outer two whorls of a flower, leading to homeotic transformations of floral organ identity as well as loss of floral organs. We isolated the LEUNIG gene by using a map-based approach and showed that LEUNIG encodes a glutamine-rich protein with seven WD repeats and is similar in motif structure to a class of functionally related transcriptional corepressors including Tup1 from yeast and Groucho from Drosophila. The nuclear localization of LEUNIG-GFP is consistent with a role of LEUNIG as a transcriptional regulator. The detection of LEUNIG mRNA in all floral whorls at the time of their inception suggests that the restricted activity of LEUNIG in the outer two floral whorls must depend on interactions with other spatially restricted factors or on posttranslational regulation. Our finding suggests that both animals and plants use similar repressor proteins to regulate critical developmental processes.

PMID:: 11058164; [PubMed - indexed for MEDLINE]
PMCID:: PMC18862

Free PMC Article

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Figure 2

Molecular cloning of LUG. (A) A physical map of LUG on chromosome 4. Open bars represent yeast artificial chromosome (YAC) and bacterial artificial chromosome (BAC) clones. The relative position of several PCR-based markers is placed above the chromosome. Cosmids 31–1 and 31-G both complemented the lug-16 mutant. (B) The protein sequence of LUG from L-er. The position of five lug mutations is indicated above the amino acid sequence. The two glutamine-rich regions are in bold. The seven WD repeats are underlined and are identified by using http://pfam.wustl.edu/hmmsearch.shtml. The specific base pair changes in each lug allele are described below based on the sequences of cosmid L23H3 (AL050398). lug-3 causes a C to T change at 25309; lug-12 causes a C to T change at 25198; lug-16 causes a G to A change at 24693; lug-1 mutation causes a G to A change at 26267; lug-14 mutation inserts an A after 29080. (C) Structural similarity between LUG, LUH (AC 003974), the S. cerevisiae Tup1 (19), and the Drosophila Gro (20). Numbers above and in parentheses correspond to amino acids. The percentage between the amino acid numbers indicates the level of identity between LUG and LUH. The LUFS domain in LUG and LUH is indicated by a dotted region. A second highly conserved region between LUG and LUH immediately precedes the WD repeats and is marked by wavy lines. The level of similarity is identified by using http://www.bioinformatix.com/sas/. (D) Sequence alignment in the LUFS domain among LUG, LUH (AC003974), Flo8, and a human single-strand DNA-binding protein (AF077048). Numbers correspond to amino acids. Flo8 has extra 21 aa indicated by (X)21. Amino acids conserved in all four genes are in bold and are indicated by *. Amino acids conserved in three of the four genes are in bold and are indicated by :.

LEUNIG, a putative transcriptional corepressor that regulates AGAMOUS expression during flower development

Proc Natl Acad Sci U S A. 2000 November 7;97(23):12902-12907.