The Major Facilitator Superfamily(MFS)is ubiquitous in living organisms and represents the largest group of secondary active membrane transporters.In plants,significant research efforts have focused on the role of spe...The Major Facilitator Superfamily(MFS)is ubiquitous in living organisms and represents the largest group of secondary active membrane transporters.In plants,significant research efforts have focused on the role of specific families within the MFS,particularly those transporting macronutrients(C,N,and P)that constitute the vast majority of the members of this superfamily.Other MFS families remain less explored,although a plethora of additional substrates and physiological functions have been uncovered.Nevertheless,the lack of a systematic approach to analyzing the MFS as a whole has obscured the high diversity and versatility of these transporters.Here,we present a phylogenetic analysis of all annotated MFS domaincontaining proteins encoded in the Arab/dops/s fA?a//ana genome and propose that this superfamily of transporters consists of 218 members,clustered in 22 families.In reviewing the available information regarding the diversity in biological functions and substrates of Arab/dops/s MFS members,we provide arguments for intensified research on these membrane transporters to unveil the breadth of their physiological relevance,disclose the molecular mechanisms underlying their mode of action,and explore their biotechnological potential.展开更多
Serine/arginine-rich(SR)proteins are conserved splicing regulators that play important roles in plant stress responses,namely those mediated by the abscisic acid(ABA)hormone.The Arabidopsis thaliana SR-like protein SR...Serine/arginine-rich(SR)proteins are conserved splicing regulators that play important roles in plant stress responses,namely those mediated by the abscisic acid(ABA)hormone.The Arabidopsis thaliana SR-like protein SR45 is a described negative regulator of the ABA pathway during early seedling development.How the inhibition of growth by ABA signaling is counteracted to maintain plant development under stress conditions remains largely unknown.Here,we show that SR45 overexpression reduces Arabidopsis sensitivity to ABA during early seedling development.Biochemical and confocal microscopy analyses of transgenic plants expressing fluorescently tagged SR45 revealed that exposure to ABA dephosphorylates the protein at multiple amino acid residues and leads to its accumulation,due to SR45 stabilization via reduced ubiquitination and proteasomal degradation.Using phosphomutant and phosphomimetic transgenic Arabidopsis lines,we demonstrate the functional relevance of ABA-mediated dephosphorylation of a single SR45 residue,T264,in antagonizing SR45 ubiquitination and degradation to promote its function as a repressor of seedling ABA sensitivity.Our results reveal a mechanism that negatively autoregulates ABA signaling and allows early plant growth under stress via posttranslational control of the SR45 splicing factor.展开更多
文摘The Major Facilitator Superfamily(MFS)is ubiquitous in living organisms and represents the largest group of secondary active membrane transporters.In plants,significant research efforts have focused on the role of specific families within the MFS,particularly those transporting macronutrients(C,N,and P)that constitute the vast majority of the members of this superfamily.Other MFS families remain less explored,although a plethora of additional substrates and physiological functions have been uncovered.Nevertheless,the lack of a systematic approach to analyzing the MFS as a whole has obscured the high diversity and versatility of these transporters.Here,we present a phylogenetic analysis of all annotated MFS domaincontaining proteins encoded in the Arab/dops/s fA?a//ana genome and propose that this superfamily of transporters consists of 218 members,clustered in 22 families.In reviewing the available information regarding the diversity in biological functions and substrates of Arab/dops/s MFS members,we provide arguments for intensified research on these membrane transporters to unveil the breadth of their physiological relevance,disclose the molecular mechanisms underlying their mode of action,and explore their biotechnological potential.
基金This work was funded by the Fundac¸ao para a Ciencia e a Tecnologia(FCT)through grant PTDC/ASP-PLA/2550/2021 and a PhD fellowship PD/BD/128401/2017 awarded to R.A.-M.Funding from the research unit GREEN-it"Bioresources for Sustainability"(UIDB/04551/2020)is also acknowledgedA.M.J.and J.R.were funded by the Gatsby Charitable Foundation and BBSRC(BB/P018572/1).
文摘Serine/arginine-rich(SR)proteins are conserved splicing regulators that play important roles in plant stress responses,namely those mediated by the abscisic acid(ABA)hormone.The Arabidopsis thaliana SR-like protein SR45 is a described negative regulator of the ABA pathway during early seedling development.How the inhibition of growth by ABA signaling is counteracted to maintain plant development under stress conditions remains largely unknown.Here,we show that SR45 overexpression reduces Arabidopsis sensitivity to ABA during early seedling development.Biochemical and confocal microscopy analyses of transgenic plants expressing fluorescently tagged SR45 revealed that exposure to ABA dephosphorylates the protein at multiple amino acid residues and leads to its accumulation,due to SR45 stabilization via reduced ubiquitination and proteasomal degradation.Using phosphomutant and phosphomimetic transgenic Arabidopsis lines,we demonstrate the functional relevance of ABA-mediated dephosphorylation of a single SR45 residue,T264,in antagonizing SR45 ubiquitination and degradation to promote its function as a repressor of seedling ABA sensitivity.Our results reveal a mechanism that negatively autoregulates ABA signaling and allows early plant growth under stress via posttranslational control of the SR45 splicing factor.
