title: Interaction of FIE, a polycomb protein, with pRb: a possible mechanism regulating endosperm development.
abstract: Inactivation of the Arabidopsis protein FERTILIZATION INDEPENDENT ENDOSPERM (FIE) induces division of the central cell of the embryo sac, leading to endosperm development in the absence of fertilization. The mechanism whereby FIE regulates this process is unknown. We postulated that activation of central cell division in fie mutant plants might involve the retinoblastoma protein (pRb), a cell cycle regulatory element. Pull-down and surface plasmon resonance assays demonstrated that FIE interacts in-vitro with the pRb homologues from Arabidopsis (AtRb), maize (ZmRb) and human (HuRb). The interaction of FIE with ZmRB and HuRb in the yeast two-hybrid system supports the possibility that a FIE-pRb interaction may occur also in planta. Mutational analysis showed that this interaction does not occur via the LxCxE motif of the FIE protein nor via the pocket B domain of pRb. These results suggest that FIE may inhibit premature division of the central cell of the embryo sac, at least partly, through interaction with pRb, and suppression of pRb-regulated genes.
authors.affiliation: Department of Plant Sciences, Tel-Aviv University, 69978, Tel Aviv, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Mosquna
authors.forename: A
authors.initials: A
authors.lastname: Katz
authors.forename: S
authors.initials: S
authors.lastname: Shochat
authors.forename: G
authors.initials: G
authors.lastname: Grafi
authors.forename: N
authors.initials: N
authors.lastname: Ohad
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D006801:Humans; D009154:Mutation; D030821:Plants, Genetically Modified; D025941:Protein Interaction Mapping; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D016160:Retinoblastoma Protein / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000737:chemistry; D020349:Surface Plasmon Resonance; D003313:Zea mays
chemical_list: D029681:Arabidopsis Proteins; C118816:FIE protein, Arabidopsis; D012097:Repressor Proteins; D016160:Retinoblastoma Protein