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標題: The C-terminal sequence of LMADS1 is essential for the formation of homodimers for B function proteins
作者: Tzeng, T.Y.
Liu, H.C.
Yang, C.H.
關鍵字: mads-box genes;floral organ identity;homeotic gene;flower;development;molecular evolution;multigene family;arabidopsis;apetala3;expression;pistillata
Project: Journal of Biological Chemistry
期刊/報告no:: Journal of Biological Chemistry, Volume 279, Issue 11, Page(s) 10747-10755.
LMADS1, a lily ( Lilium longiflorum) AP3 orthologue, contains the complete consensus sequence of the paleoAP3 ( YGSHDLRLA) and PI-derived (YEFRVQPSQPNLH) motifs in the C-terminal region of the protein. Interestingly, through yeast two-hybrid analysis, LMADS1 was found to be capable of forming homodimers. These results indicated that LMADS1 represents an ancestral form of the B function protein, which retains the ability to form homodimers in regulating petal and stamen development in lily. To explore the involvement of the conserved motifs in the C-terminal region of LMADS1 in forming homodimers, truncated forms of LMADS1 were generated, and their ability to form homodimers was analyzed using yeast two-hybrid and electrophoretic mobility shift assay. The ability of LMADS1 to form homodimers decreased once the C-terminal paleoAP3 motif was deleted. When both paleoAP3 and PI-derived motifs were deleted, the ability of LMADS1 to form homodimers was completely abolished. This result indicated that although the paleoAP3 motif promotes the formation of LMADS1 homodimers, the PI-derived motif is essential. Deletion analysis indicated that two amino acids, RV, of the 5 final amino acids, YEFRV, in the PI-derived motif are essential for the formation of homodimers. Further, point mutation analysis indicated that amino acid Val was absolutely necessary, whereas residue Arg played a less important role in the formation of homodimers. Furthermore, Arabidopsis AP3 was able to form homodimers once its C-terminal region was replaced by that of LMADS1. This result indicated that the C-terminal region of LMADS1 is responsible and essential for homodimer formation of the ancestral form of the B function protein.
ISSN: 0021-9258
DOI: 10.1074/jbc.M311646200
Appears in Collections:生物科技學研究所

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