Abstract
Members of the P4 subfamily of P-type ATPases are believed
to catalyze transport of phospholipids across cellular bilayers.
However, most P-type ATPases pump small cations or metal
ions, and atomic structures revealed a transport mechanism that
is conserved throughout the family. Hence, a challenging problem
is to understand how this mechanism is adapted in P4-
ATPases to flip phospholipids. P4-ATPases form heteromeric
complexes with Cdc50 proteins. The primary role of these additional
polypeptides is unknown. Here, we show that the affinity
of yeast P4-ATPase Drs2p for its Cdc50-binding partner fluctuates
during the transport cycle, with the strongest interaction
occurring at a point where the enzyme is loaded with phospholipid
ligand. We also find that specific interactions with Cdc50p
are required to render the ATPase competent for phosphorylation
at the catalytically important aspartate residue. Our data
indicate that Cdc50 proteins are integral components of the
P4-ATPase transport machinery. Thus, acquisition of these subunits
may have been a crucial step in the evolution of flippases
from a family of cation pumps.
Original language | Undefined/Unknown |
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Pages (from-to) | 17956-17967 |
Number of pages | 12 |
Journal | Journal of Biological Chemistry |
Volume | 284 |
Issue number | 27 |
Publication status | Published - 2009 |