The Versatile Role of Plant Aquaglyceroporins in Metalloid Transport

Abstract

AbstractMetalloids are elements with intermediate chemical properties between metals and nonmetals. The metalloids are biologically important elements, ranging from essential to extremely toxic elements with contrasting effects on organisms. Plants deal with a considerable imbalance of metalloids in the environment. Plants must acquire adequate amounts of essential metalloids for metabolism or contrarily exclude toxic metalloids to avoid cellular toxicity. The process of uptake and exclusion is guided by channel proteins, which transport metalloids across cellular membranes. Major intrinsic proteins (MIPs) are a family of selective channels that includes aquaporins (water channels) and aquaglyceroporins (glycerol and other solute channels). Aquaglyceroporin facilitates the transport of small solutes, including glycerol, small uncharged solutes, and gasses across biological membranes. Plant MIPs are grouped into five subfamilies based on sequence similarity and subcellular localization. Plant MIPs are mainly categorized into five subfamilies – plasma membrane intrinsic proteins (PIPs), nodulin-26-like intrinsic proteins (NIPs), tonoplast intrinsic proteins (TIPs), small basic intrinsic proteins (SIPs), and uncharacterized intrinsic proteins (XIPs). The uptake of environmental metalloids by aquaglyceroporins explains how beneficial elements such as silicon are taken up in plants. Conversely, toxic elements such as arsenic and antimony also enter the food chain via these channel proteins. The present review summarizes the role of various MIP homologs for transporting metalloids into and out of plant cells. This review discusses the detailed mechanism of MIPs for acquiring essential metalloids and their role in the influx and efflux in plant cells.KeywordsMetalloidsMajor intrinsic proteinsAquaglyceroporinsHomeostasisToxicity