A Critical View on ABC Transporters and Their Interacting Partners in Auxin Transport

Abstract

Different subclasses of ATP-binding cassette (ABC) transporters have been implicated in the transport of native variants of the phytohormone auxin. Here, the putative, individual roles of key members belonging to the ABCB, ABCD and ABCG families, respectively, are highlighted and the knowledge of their assumed expression and transport routes is reviewed and compared with their mutant phenotypes. Protein-protein interactions between ABC transporters and regulatory components during auxin transport are summarized and their importance is critically discussed. There is a focus on the functional interaction between members of the ABCB family and the FKBP42, TWISTED DWARF1, acting as a chaperone during plasma membrane trafficking of ABCBs. Further, the mode and relevance of functional ABCB-PIN interactions is diagnostically re-evaluated. A new nomenclature describing precisely the most likely ABCB-PIN interaction scenarios is suggested. Finally, available tools for the detection and prediction of ABC transporter interactomes are summarized and the potential of future ABC transporter interactome maps is highlighted.

Out of Shape During Stress: A Key Role for Auxin

“…Another large family of auxin carriers influencing auxin flow in the root is the ABCB transporter family [11]. Recently, several studies have shown a role for ABCB transporters during salt stress.…”

PIN FORMED 2 facilitates the transport of Arsenite inArabidopsis thaliana

“…PINs have been shown to interact with another group of membrane transporter family protein PGP/ABCBs (ATP-binding cassette transporters of the B subfamily), involved in auxin transport (Blakeslee et al, 2007; Zazímalová et al, 2010; Cho et al, 2012; Geisler et al, 2017). “Concerted” interactions have been shown between ABCB19 and PIN1 or ABCB1/ABCB4 and PIN2 in auxin transport in polar PM domains, where ABCBs and PINs can physically interact (Blakeslee et al, 2007; Titapiwatanakun et al, 2009; Cho et al, 2012).…”

“…“Concerted” interactions have been shown between ABCB19 and PIN1 or ABCB1/ABCB4 and PIN2 in auxin transport in polar PM domains, where ABCBs and PINs can physically interact (Blakeslee et al, 2007; Titapiwatanakun et al, 2009; Cho et al, 2012). It was also proposed that while members of the ABCB and PIN families can function as independent auxin transport catalysts, “a strict co-operative or mutual functionality” cannot be excluded (Geisler et al, 2017). In many organisms, proteins from PGP/ABCB/MDR group are involved in active efflux of various xenobiotics, including metals, from the cells.…”

Seeing is better than believing: visualization of membrane transport in plants

“…However, presence of a transporter on a cellular subdomain does not automatically reflect local activity levels. Moreover, this approach failed so far in the prediction of transport routes for non-polar transporters known to be involved in long-distance transport [12].…”