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上海士鋒生物關于轉運蛋白家族雙重作用的介紹
點擊次數：1669 發布時間：2013-5-21
研究人員發現，在根部ZIFL1編碼的蛋白對生長素運輸至關重要，是植物生長和發育*的激素。然而，在葉片中，ZIFL1編碼的蛋白能促進植物耐旱性。
這項研究中的基因能編碼兩種蛋白且發揮不同生物學功能，實屬少數。ZIFL1屬于轉運蛋白家族基因，存在于所有生物類別。但多數家族成員的功能尚不清楚。目前已知的是轉運基因編碼的蛋白能整合至細胞膜，并允許小分子通過他們。
通過對模式植物擬南芥進行遺傳和細胞生物學研究， Paula Duque的研究團隊對ZIFL1基因的功能進行分析。讓科學吃驚的是，無法產生ZIFL1轉運蛋白的突變植物不同的器官和功能呈現特異缺陷。一方面，與正常植物相比，他們的根生長、分枝、取向出現問題。
總之，通過確定兩個異構體亞細胞和組織分布，選擇性剪切確定了ZIFL1轉運蛋白的雙重作用。
原文摘要：
A Major Facilitator Superfamily Transporter Plays a Dual Role in Polar Auxin Transport and Drought Stress Tolerance in Arabidopsis
Many key aspects of plant development are regulated by the polarized transport of the phytohormone auxin. Cellular auxin efflux, the rate-limiting step in this process, has been shown to rely on the coordinated action of PIN-formed （PIN） and B-type ATP binding cassette （ABCB） carriers. Here, we report that polar auxin transport in the Arabidopsis thaliana root also requires the action of a Major Facilitator Superfamily （MFS） transporter, Zinc-Induced Facilitator-Like 1 （ZIFL1）. Sequencing, promoter-reporter, and fluorescent protein fusion experiments indicate that the full-length ZIFL1.1 protein and a truncated splice isoform, ZIFL1.3, localize to the tonoplast of root cells and the plasma membrane of leaf stomatal guard cells, respectively. Using reverse genetics, we show that the ZIFL1.1 transporter regulates various root auxin-related processes, while the ZIFL1.3 isoform mediates drought tolerance by regulating stomatal closure. Auxin transport and immunolocalization assays demonstrate that ZIFL1.1 indirectly modulates cellular auxin efflux during shootward auxin transport at the root tip, likely by regulating plasma membrane PIN2 abundance. Finally, heterologous expression in yeast revealed that ZIFL1.1 and ZIFL1.3 share H+-coupled K+transport activity. Thus, by determining the subcellular and tissue distribution of two isoforms, alternative splicing dictates a dual function for the ZIFL1 transporter. We propose that this MFS carrier regulates stomatal movements and polar auxin transport by modulating potassium and proton fluxes in Arabidopsiscells.