ABC transporters are transmembrane proteins that utilise the energy offered by ATP to perform various biological processes. One such process is the translocation of molecules (metabolites, toxic substances, ions) across membranes. In plants, ABC transporters regulate stomatal movement, the pores found in the epidermis of leaves. Arabidopsis thaliana contains about 130 ABC proteins which participate in the transport of different substances. Understanding the mechanisms of hormone transport such as auxin is also important for breeding purposes and could further be exploited for biomass production. In mammalian cells, ABC transporters confer resistance to drugs in cancer cells and also cause disease, such as in the case of cystic fibrosis. The EU-funded ABC TRANSPORTER project wished to analyse the sequence of ABC transporters in plants and associate it with their substrate specificity. Considerable part of the work was devoted to the identification of the binding partner of the AtABCB14 importer protein which helps malate enter plant cells under high carbon dioxide concentrations. In search of transporters of weak acids in yeast, scientists identified two genes which confer acetic acid resistance. To investigate the impact of these genes on the plant phenotype, they generated mutants in the model plant Arabidopsis thaliana. Knockout of the AtABCC8 gene induced a lower coniferin, monolignol glucoside content than that of wild type. This clearly indicated that ABC transporters have more than one substrate and that AtABCC8 could participate both in acid and monolignol glucoside transport. This may be helpful to understand the mechanism of lignin accumulation and enable the breeding of plants with reduced lignin content, suitable for bioenergy production. Taken together, the results of the ABC TRANSPORTER study provide important insight into plant development and growth. Furthermore, given the medical importance of ABC transporters, the generated knowledge could be extrapolated to human cells and may help identify novel pharmaceutical targets.
Bioenergy, ABC transporter, ATP, Arabidopsis thaliana, protein, auxin, breeding, biomass, AtABCB14, monolignol glucoside, lignin