Biology subjects

di Donato, M.

Publications and source records attributed to di Donato, M..

3 recordsLinked to original sources

bioRxiv2026

The FKBP42, TWISTED DWARF1, prioritizes auxin over brassinosteroidtransport by peptidyl-prolyl cis-trans isomerization of ABCB1

The ATP-binding cassette (ABC) transporter ABCB1 transports both auxins and the brassinosteroid brassinolide (BL). ABCB1-mediated auxin (IAA) transport depends on interaction with the FKBP42 protein TWISTED DWARF1 (TWD1), yet the mechanism underlying substrate selectivity remains unclear. Here, we confirm dual IAA and BL transport by ABCB1 and show that the two substrates compete for ABCB1-mediated transport. We demonstrate that a conserved proline residue (P1008) is required for IAA, but not BL, transport. Furthermore, we identify TWD1 as a calmodulin-activated peptidyl-prolyl cis-trans isomerase (PPIase) that selectively enhances IAA, but not BL, transport through isomerization of the E1007-P1008 peptide bond. Loss of TWD1 PPIase activity abolishes ABCB1-mediated IAA export without affecting BL transport, revealing a regulatory mechanism that prioritizes auxin over brassinosteroid transport. Cryo-EM, molecular docking, and molecular dynamics simulations of wild-type ABCB1 and the ABCB1P1008G variant suggest that the P1008 loop mediates long-range communication between the nucleotide-binding domain surface and the substrate-binding pocket, thereby providing a structural mechanism by which TWD1 modulates substrate specificity. In summary, our findings establish the structural basis of ABCB1 substrate selectivity and uncover a post-translational mechanism that selectively regulates auxin transport while preserving brassinosteroid transport. One Sentence SummaryTWD1 prioritizes ABCB1-mediated auxin over brassinosteroid transport

biochemistry↗

bioRxiv2022

TWISTED DWARF1 mediates myosin XI-associated vesicle trafficking required for auxin transport

Defects in plant development caused by loss-of the FKBP42, TWISTED DWARF1 (TWD1), have so far been accounted to a dual function of TWD1 acting as an ABCB chaperone that positively regulates ABCB biogenesis and transport activity. On the other hand, TWD1 was characterized as a modulator of actin cytoskeleton bundling and dynamics by interaction with ACTIN7, however, currently it is unclear if both events are connected. Here, we show that TWD1 positively regulates pollen tube germination and growth by controlling actin organization. We identify and verify myosin XI-K as TWD1 interacting protein, which is most likely linking the action of TWD1 on the actin cytoskeleton. We provide evidence that myosin XI-K is required for proper auxin exporter trafficking and auxin export. Further, we show that ER-localized TWD1 reshapes the ER network to overlay actin cables similar to mutations of myosin-XI and thus controls cytoplasmic streaming. In summary, our data support a model in that TWD1 functions as an ER-actin adapter proteins involved in myosin-dependent ER motility and cargo trafficking. Our findings provide a molecular explanation for the defects in early ABCB biogenesis in twd1 that are caused by defects in the three-way interaction between the ER, cytosolic myosin-XI and F-actin.

cell biology↗

bioRxiv2020

A conserved D/E-P motif in the nucleotide binding domain of plant ABCB/PGP-type ABC transporters defines their auxin transport capacity

Auxin transport activity of ABCB1 was suggested to be regulated by physical interaction with the FKBP42/Twisted Dwarf1 (TWD1), a bona fide peptidylprolyl cis-trans isomerase (PPIase), but all attempts to demonstrate such a PPIase activity on TWD1 have failed so far. By using a structure-based approach we have identified a series of surface-exposed proline residues in the C-terminal nucleotide binding fold and linker of Arabidopsis ABCB1 that do not alter ABCB1 protein stability or location but its catalytic transport activity. P1.008 was uncovered as part of a conserved signature D/E-P motif that seems to be specific for Auxin-Transporting ABCBs, we now refer to as ATAs. Beside the proline, also mutation of the acidic moiety prior to the proline abolishes auxin transport activity by ABCB1. So far, all higher plant ABCBs for that auxin transport was safely proven carry this conserved motif underlining its diagnostic potential. Introduction of this D/E-P motif into malate importer, ABCB14, increases both its malate and its background auxin transport activity, suggesting that this motif has an impact on transport capacity. The D/E-P1.008 motif is also important for ABCB1-TWD1 interaction and activation of ABCB1-mediated auxin transport by TWD1, supporting a scenario in that TWD1 acts as an activator of ABCB1 transport activity by means of its PPIase. In summary, our data imply a dual function for TWD1 acting as an ABCB co-chaperone required for ABCB biogenesis and as a putative activator of ABCB-mediated auxin transport by cis-trans isomerization of peptidyl-prolyl bonds.

biochemistry↗