A mutation of the H-loop selectively affects rhodamine transport by the yeast multidrug ABC transporter Pdr5

摘要: The yeast ABC transporter Pdr5 plays a major role in drug resistance against large number of structurally unrelated compounds. Although has been extensively studied, many important aspects regarding its molecular mechanisms remain unresolved. For example, striking degeneration conserved amino acid residues exists the nucleotide binding domains (NBDs), but their functional relevance is unknown. Here, we performed vivo and vitro experiments to address asymmetry NBDs. It became evident by ATPase activity transport studies that catalysis at only one two NBD composite sites crucial for protein function. Furthermore, mutations proposed “catalytic carboxylate” (E1036) dyad histidine” (H1068) were characterized. mutation glutamate abolished substrate transport, H1068 had no influence on ATP consumption. However, H1068A rhodamine vitro, while leaving other substrates unaffected. By contrast mammalian P-glycoprotein (P-gp), not stimulated addition substrates, indicating an uncoupled constantly hydrolyses ensure active transport. Taken together, our data provide insights into mechanism suggest solely transmembrane dictate selection.