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Lichtblau, D. M.

Publications and source records attributed to Lichtblau, D. M..

2 recordsLinked to original sources
bioRxiv2023

The small iron-deficiency-induced protein OLIVIA and its relation to the bHLH transcription factor POPEYE

Iron (Fe) is a crucial micronutrient needed in many metabolic processes. To balance needs and potential toxicity, plants control the amount of Fe they take up and allocate to leaves and seeds during their development. One important regulator of this process is POPEYE (PYE). PYE is a Fe deficiency-induced key bHLH transcription factor (TF) for allocation of internal Fe in plants. In the absence of PYE, there is altered Fe translocation and plants develop a leaf chlorosis. NICOTIANAMINE SYNTHASE4 (NAS4), FERRIC-REDUCTION OXIDASE3 (FRO3), and ZINC-INDUCED FACILITATOR1 (ZIF1) genes are expressed at higher level in pye-1 indicating that PYE represses these genes. PYE activity is controlled in a yet unknown manner. Here, we show that a small Fe deficiency-induced protein OLIVIA (OLV) can interact with PYE. OLV has a conserved C-terminal motif, that we named TGIYY. Through deletion mapping, we pinpointed that OLV TGIYY and several regions of PYE can be involved in the protein interaction. An OLV overexpressing (OX) mutant line exhibited an enhanced NAS4 gene expression. This was a mild Fe deficiency response phenotype that was related to PYE function. Leaf rosettes of olv mutants remained smaller than those of wild type, indicating that OLV promotes plant growth. Taken together, our study identified a small protein OLV as a candidate that may connect aspects of Fe homeostasis with regulation of leaf growth. HighlightsO_LIOLIVIA (OLV), a small protein, can interact with the bHLH transcription factor POPEYE (PYE) C_LIO_LIOLV has a conserved motif, named TGIYY, that can be involved in protein interaction with PYE C_LIO_LIOLV mutant plants have mild phenotypes related with PYE and NAS4 regulation. C_LIO_LIOLV promotes rosette growth. C_LI

plant biology↗
bioRxiv2021

The effector FEP3/IRON MAN1 modulates interaction between BRUTUS-LIKE1 and bHLH subgroup IVb and IVc proteins

Plants use the micronutrient iron (Fe) efficiently to balance the requirements for Fe during growth with its potential cytotoxic effects. A cascade of basic helix-loop-helix (bHLH) transcription factors is initiated by bHLH proteins of the subgroups IVb and IVc. This induces more than 50 genes in higher plants that can be grouped in co-expression clusters. Gene co-expression networks contain information on functional protein interactomes. We conducted a targeted yeast two-hybrid screen with pairwise combinations of 23 proteins stemming from previously characterized Fe-deficiency-induced gene co-expression clusters and regulators. We identified novel and described interactions, as well as interaction hubs with multiple interactions within the network. We found that BRUTUS-LIKE E3 ligases (BTSL1, BTSL2) interacted with basic helix-loop-helix (bHLH) transcription factors of the subgroups IVb and IVc including PYE, bHLH104 and ILR3, and with small FE UPTAKE-INDUCING PEPTIDE3/IRON MAN1 (FEP3/IMA1). Through deletion studies and with support of molecular docking, we mapped the interaction sites to three-amino-acid regions in BTSL1 and FEP3/IMA1. The FEP3/IMA1 active residues are present in interacting sites of the bHLH IVc factors. FEP3/IMA1 attenuated interaction of BTSL1 with bHLH proteins in a quantitative yeast three-hybrid assay suggesting that it is an inhibitor. Co-expression of BTSL1 and bHLH IVb and IVc factors uncovered unexpected patterns of subcellular localization. Combining deletion mapping, protein interaction and physiological analysis, we discuss the model that FEP3/IMA1 is a small effector protein inhibiting BTSL1/BTSL2-mediated degradation of bHLH subgroup IVb and IVc proteins. HighlightsO_LIA targeted yeast two-hybrid screen of Fe deficiency-regulated proteins reveals a regulatory protein interactome consisting of E3 ligases BTS/BTSL, bHLH transcription factors of subgroups IVb and IVc and small protein FEP3/IMA1. C_LIO_LIInteraction sites between BTSL1, FEP3/IMA1, and bHLH IVc transcription factors were fine-mapped. C_LIO_LIFEP3/IMA1 is as a small effector protein that selectively attenuates the bHLH interaction with BTSL1 to regulate Fe deficiency responses. C_LI One sentence summaryA targeted protein interaction screen uncovered a interactions of E3 ligase BTSL1, bHLH proteins of subgroup IVb and IVc and effector protein FEP3/IMA1 to regulate Fe deficiency responses.

plant biology↗