Dissection of Functional Modules of AT-HOOK MOTIF NUCLEAR LOCALIZED PROTEIN 4 in the Development of the Root Xylem

Abstract

Xylem development in the Arabidopsis root apical meristem requires a complex cross talk between plant hormone signaling and transcriptional factors (TFs). The key processes involve fine-tuning between neighboring cells, mediated via the intercellular movement of signaling molecules. As an example, we previously reported that AT-HOOK MOTIF NUCLEAR LOCALIZED PROTEIN (AHL) 4 (AHL4), a member of the 29 AT-hook family TFs in Arabidopsis, moves into xylem precursors from their neighbors to determine xylem differentiation. As part of the effort to understand the molecular functions of AHL4, we performed domain swapping analyses using AHL1 as a counterpart, finding that AHL4 has three functionally distinctive protein modules. The plant and prokaryotes conserved (PPC) domain of AHL4 acts as a mediator of protein–protein interactions with AHL members. The N-terminus of AHL4 is required for the regulation of xylem development likely via its unique DNA-binding activity. The C-terminus of AHL4 confers intercellular mobility. Our characterization of modules in the AHL4 protein will augment our understanding of the complexity of regulation and the evolution of intercellular mobility in AHL4 and its relatives.

The Danger-Associated Peptide PEP1 Directs Cellular Reprogramming in the Arabidopsis Root Vascular System

“…4 ). Based on the section images, we categorized vessel organizations into four types, as reported previously ( Seo and Lee, 2021 ). The first type is defined as “five xylem cells” with two protoxylem cells on opposite ends along the xylem axis and three metaxylem cells between them ( Figs.…”

“…S4 ). We previously reported that AT-hook motif nuclear localized proteins (AHLs) tightly control the xylem-procambium boundaries ( Seo and Lee, 2021 ; Zhou et al, 2013 ). However, it is not known whether AHL transcriptional networks are influenced by PEP1.…”

“…Confocal microscopy was performed on a Zeiss LSM700 and a Leica TCS SP8 confocal laser scanning microscope as previously reported ( Kim et al, 2020 ; Seo and Lee, 2021 ). Pictures were taken with either a 20× dry objective lens or a 63× water-immersion objective lens.…”

AHL10 phosphorylation determines RRP6L1 chromatin association and growth suppression during water stress

“…AHLs bind AT-rich DNA sequences via their N-terminal AT-hook domain (Fujimoto et al, 2004;Zhao et al, 2013). AHLs also contain a Plant and Prokaryote Conserved (PPC)/DUF296 domain which is involved in self-interaction, or cross-interaction among AHLs, to form trimers (Fujimoto et al, 2004;Seo and Lee, 2021). In contrast to many other types of transcriptional regulators, AHLs bind the minor groove of DNA and it has been proposed that binding of AHL complexes to AT-rich sites can modify DNA architecture to bring to together loops of DNA and place otherwise distal elements in close proximity to induce the formation of transcriptional regulatory complexes (Zhao et al, 2013;Franco-Zorrilla et al, 2014).…”

Systematical Characterization of the AT-Hook Gene Family in Juglans regia L. and the Functional Analysis of the JrAHL2 in Flower Induction and Hypocotyl Elongation

“…AT-hook motifs can be divided into two categories according to the conserved amino acid sequence: Type-I AT-hook motif contains ‘Gly-Ser-Lys-Asn-Lys’ consensus sequences at the end of the ‘Arg-Gly-Arg’ core, while the Type-II contains ‘Arg-Lys-Tyr.’ The PPC domain, also known as the Domain of Unknown Function #296 (DUF296), is also found in, archaea, prokaryotes, and higher plants. The PPC domain was involved in the physical interaction with other AHL (or themselves) or nuclear proteins [ 1 , 4 ]. According to sequence differences, the PPC can be divided into two categories: Type-A and Type-B.…”