open access

https://hdl.handle.net/2115/68388

Loop 5 region is important for the activity of the long-chain base transporter Rsb1

英語

transporter

2017-02

Oxford University Press

Journal of biochemistry

161(2)

207-213

Intracellular lipid amounts are regulated not only by metabolism but also by efflux. Yeast Rsb1 is the only known transporter/floppase of the sphingolipid components long-chain bases (LCBs). However, even fundamental knowledge about Rsb1, such as important amino acid residues for activity and substrate recognition, still remains unclear. Rsb1 belongs to the Rtal-like family. To date, it has not been determined whether all family members share a common ability to export LCBs. Here, we revealed that within the Rtal-like family, only Rsb1 suppressed the hypersensitivity of the mutant cells lacking LCB 1-phoshate-degrading enzymes, suggesting that LCB-exporting activity is specific to Rsb1. Rsb1 contains a characteristic region (loop 5), which does not exist in other proteins of the Rtal-like family. We found that deletion of this region caused loss of Rsb1 function. Further mutational analysis of loop 5 revealed that the charged amino acid residues E223, D225 and R236 were important for Rsb1 activity. In addition to LCBs, Rsb1 facilitated the export of 1-hexadecanol, but not pahnitic acid, which suggests that Rsb1 recognizes the C1 hydroxyl group. Thus, our findings provide an important clue for understanding the molecular mechanism of LCB export.

学術雑誌論文

Accepted Manuscript

This is a pre-copyedited, author-produced version of an article accepted for publication in Journal of Biochemistry following peer review. The version of record 161(2), 207-213, 2017 is available online at: DOI:10.1093/jb/mvw059.

0021-924X