Pumping with plant P-type ATPases

Abstract

In the past 10 years, research on P-type ATPases in plants has advanced from its roots in biochemistry to molecular biology, genetics, structure, and back to biochemistry. Since the first cloning of a plant proton pump, plant genes have been identified from all five groups of P-type ATPases. These pumps have been implicated in the transport of multiple ions, including protons, calcium, manganese, molybdenum, copper, and phospholipids. To mediate similar cellular functions, plants and animals in some cases utilize entirely different ion pumps. For example, plants utilize an H+ATPase instead of an Na+/K+-ATPase to energize the plasma membrane with an electrochemical gradient. Another distinction between plants and animals is that in some cases similar pumps are used in different subcellular locations. For example, while in animals the ‘plasma membrane’-type calmodulin-regulated Ca2+-ATPases are exclusively found in plasma membrane, several plant homologues have been found in endomembrane locations, such as the ER and tonoplast. Through multidisciplinary approaches the next decade should reveal insights into important questions, including: What are the ion specificities of various divergent pumps? What are the structural changes mediating ion translocation? What are the cellular and organismal functions of different pumps? How are pumps regulated? and, ultimately, How can we use our knowledge of P-type ATPases for applications in agriculture?