Identification and analysis of proteins that interact with the Avena fatua homologue of the maize transcription factor VIVIPAROUS 1

Abstract

SummaryThe Avena fatua (wild oat) homologue of VIVIPAROUS 1 (AfVP1) has been implicated in controlling the maintenance of embryo dormancy in mature imbibed seeds, but the detailed mechanisms by which this transcription factor family activates embryo maturation pathways and simultaneously represses germination are not known. A two-hybrid screen in yeast identi®ed three proteins that interacted speci®cally with AfVP1 (AfVP1 interacting proteins; AfVIPs). AfVIPs 2 and 3 interacted with the C-terminus of AfVP1, which contains the B2 + B3 domains, previously shown to bind DNA, whereas AfVIP1 interacted with the isolated B3 domain. Using puri®ed proteins in in vitro experiments, all three AfVIPs were shown also to interact with the Arabidopsis homologue ABSCISIC ACID INSENSITIVE 3 (ABI3). The three AfVIPs were expressed in both dormant and non-dormant embryos, but the abundance of AfVIP1 and 3 transcripts was greater in germinated than dormant seeds, whereas transcripts of AfVIP2 (and AfVP1) were more highly expressed in dormant embryos. The AfVIP3 protein has homology to a human cell-crisis gene with a predicted role in the cell cycle; AfVIP2 contains a ring-type zinc ®nger motif. These homologies, together with analysis of expression studies, suggest that these proteins may play speci®c roles in AfVP1-mediated regulation of the dormancy to germination transition in A. fatua seeds.

S Phase Progression Is Required for Transcriptional Activation of the β-Phaseolin Promoter

“…7C). A yeast two-hybrid screen for interacting partners of VP1 and ABI3 identified AIP3, a protein with sequence similarities to human transcription factor C1 (36,49) that is thought to have a role in cell cycle control (50). The lack of any substantial decrease for aip3 transcripts in inhibitor-treated samples (Fig.…”

Annotations and Functional Analyses of the RiceWRKYGene Superfamily Reveal Positive and Negative Regulators of Abscisic Acid Signaling in Aleurone Cells

“…Instead, only two elements are present in this promoter fragment: the ABA response element (ABRE) that is bound by ABI5 or its related bZIP proteins (Kim and Thomas, 1998;Hobo et al, 1999;Finkelstein and Lynch, 2000;Casaretto and Ho, 2003) and CE1 that is bound by an APETALA2 domain containing transcription factor ABI4 (Finkelstein et al, 1998;Niu et al, 2002). It is suggested (Shen et al, 1996) that the interaction of ABRE and CE-binding proteins might be mediated by VP1, which also interacts with 14-3-3 protein, ring (C 3 HC 3 -type) finger proteins, and RNA polymerase II subunit RPB5 (Schultz et al, 1998;Hobo et al, 1999;Jones et al, 2000;Kurup et al, 2000). Hence, OsWRKY72 and -77 might, as a non-DNA-binding component, form a complex with VP1, 14-3-3 protein, ring (C 3 HC 3 -type) finger proteins, ABI4, and ABI5 to modulate ABA signaling in aleurone cells.…”

A Conifer ABI3-Interacting Protein Plays Important Roles during Key Transitions of the Plant Life Cycle

“…In angiosperms, several proteins that interact with ABI3 and VP1 have been identified by yeast (Saccharomyces cerevisiae) twohybrid methods (Hobo et al, 1999b;Jones et al, 2000;Kurup et al, 2000;Nakamura et al, 2001). A bZIP factor, TRAB1, was isolated and showed bona fide interactions with both VP1 and with ABREs of target genes (Hobo et al, 1999b).…”