Multidrug And Toxic Compound Extrusion Proteins Research Articles

Cr(VI) behaves differently than Cr(III) in the uptake, translocation and detoxification in rice roots

Excessive accumulation of chromium (Cr) causes severe damage to both physiological and biochemical processes and consequently growth repression in plants. Hexavalent chromium [Cr(VI)]-elicited alterations in plants have been widely elucidated at either physiological or molecular level, whereas little is known about trivalent chromium [Cr(III)]. Here, we found that both Cr(III) and Cr(VI) significantly inhibited root growth in rice plants. However, rice plants under Cr(VI) showed significantly less inhibition in root growth than those under Cr(III) at low levels, which might be attributed to the different hormetic effects of Cr(III) and Cr(VI) on rice plants. It was unexpected that Cr(III) could be actively taken up by rice roots similarly to Cr(VI); whereas they exhibited different kinetic uptake patterns. Furthermore, root-to-shoot Cr translocation under Cr(VI) was much lower than that under Cr(III). These results indicate that the uptake, translocation, and toxicity of Cr(III) differed greatly from those of Cr(VI). Transcriptome profiling of rice roots revealed that a series of gene families involved in detoxification, including ATP-binding cassette (ABC) transporters, multidrug and toxic compound extrusion proteins (MATEs), and Tau class glutathione S-transferases (GSTUs), were significantly associated with Cr accumulation and detoxification in rice roots. In addition, much more members of these gene families were upregulated by Cr(VI) compared to Cr(III), suggesting their vital roles in Cr uptake, translocation, and detoxification, especially under Cr(VI) stress. Further comparison of gstu9 and gstu10/50 mutants with their wild type confirmed that GSTUs play complex roles in the intracellular Cr transport and redox homeostasis during Cr(III) or Cr(VI) stress. Taken together, our findings provides new insights into the differential behaviors of Cr(III) and Cr(VI) in rice roots, as well as new candidate genes such as OsABCs and OsGSTUs, to further elucidate the mechanisms of the uptake, translocation, and detoxification of Cr(III) and Cr(VI).

Characterization and expression analysis of MATEs in Cannabis sativa L. reveals genes involving in cannabinoid synthesis.

The medicinal plant Cannabis sativa L. (C. sativa) accumulates plant cytotoxic but medicinally important cannabinoids in glandular trichomes and flowers of female plants. Although the major biosynthetic pathway of cannabinoids has been revealed, their transportation mechanism is still unknown. Multidrug and toxic compound extrusion proteins (MATEs) can transport plant metabolites, ions and phytohormones intra and inter-cellularly. MATEs could have the potential to translocate cannabinoids or their synthetic intermediates to cellular compartment, thus protecting them from unwanted modifications and cytotoxicity. In this study, we performed a genome-wide identification and expression analysis of Cannabis sativa MATEs (CsMATEs) and revealed 42 CsMATEs that were classified phylogenetically into four conserved subfamilies. Forty-two CsMATEs were unevenly distributed on 10 chromosomes, with 50% CsMATEs were physically adjacent to at least one another CsMATEs and 83% CsMATEs localized on plasma membrane. Tandem duplication is the major evolutionary driving force for CsMATEs expansion. Real-time quantitative PCR revealed CsMATE23, CsMATE28 and CsMATE34 mainly expressed in flower, whereas CsMATE17 and CsMATE27 showed strong transcription in root. Light responsive cis-acting element was most abundant in promoters of CsMATE23, CsMATE28 and CsMATE34. Finally, the contents of cannabinoids and corresponding biosynthetic intermediates as well as expressions of CsMATE28 and CsMATE34 were determined under UV-B treatment, among which strong correlation was found. Our results indicates that CsMATEs might involve in biosynthesis of cannabinoids and has the potential to be used in heterologous production of cannabinoids.

ClbM is a versatile, cation-promiscuous MATE transporter found in the colibactin biosynthetic gene cluster

Multidrug transporters play key roles in cellular drug resistance to toxic molecules, yet these transporters are also involved in natural product transport as part of biosynthetic clusters in bacteria and fungi. The genotoxic molecule colibactin is produced by strains of virulent and pathobiont Escherichia coli and Klebsiella pneumoniae. In the biosynthetic cluster is a multidrug and toxic compound extrusion protein (MATE) proposed to transport the prodrug molecule precolibactin across the cytoplasmic membrane, for subsequent cleavage by the peptidase ClbP and cellular export. We recently determined the X-ray structure of ClbM, and showed preliminary data suggesting its specific role in precolibactin transport. Here, we define a functional role of ClbM by examining transport capabilities under various biochemical conditions. Our data indicate ClbM responds to sodium, potassium, and rubidium ion gradients, while also having substantial transport activity in the absence of alkali cations.

Expression of OsMATE1 and OsMATE2 alters development, stress responses and pathogen susceptibility in Arabidopsis

Multidrug and Toxic compound Extrusion proteins (MATE) are a group of secondary active transporters with ubiquitous occurrences in all domains of life. This is a newly characterized transporter family with limited functional knowledge in plants. In this study, we functionally characterised two members of rice MATE gene family, OsMATE1 and OsMATE2 through expression in heterologous system, Arabidopsis. Expression of OsMATEs in Arabidopsis altered growth and morphology of transgenic plants. Genome-wide expression analysis revealed modulation of genes involved in plant growth, development and biotic stress in transgenic lines. Transgenic plants displayed sensitivity for biotic and abiotic stresses. Elevated pathogen susceptibility of transgenic lines was correlated with reduced expressions of defence related genes. Promoter and cellular localization studies suggest that both MATEs express in developing and reproductive organs and are plasma-membrane localised. Our results reveal that OsMATE1 and OsMATE2 regulate plant growth and development as well as negatively affect disease resistance.