RT Journal Article
SR Electronic
T1 Pumping mechanism of NM-R3, a light-driven bacterial chloride importer in the rhodopsin family
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP eaay2042
DO 10.1126/sciadv.aay2042
VO 6
IS 6
A1 Yun, Ji-Hye
A1 Ohki, Mio
A1 Park, Jae-Hyun
A1 Ishimoto, Naito
A1 Sato-Tomita, Ayana
A1 Lee, Wonbin
A1 Jin, Zeyu
A1 Tame, Jeremy R. H.
A1 Shibayama, Naoya
A1 Park, Sam-Yong
A1 Lee, Weontae
YR 2020
UL http://advances.sciencemag.org/content/6/6/eaay2042.abstract
AB A newly identified microbial rhodopsin, NM-R3, from the marine flavobacterium Nonlabens marinus, was recently shown to drive chloride ion uptake, extending our understanding of the diversity of mechanisms for biological energy conversion. To clarify the mechanism underlying its function, we characterized the crystal structures of NM-R3 in both the dark state and early intermediate photoexcited states produced by laser pulses of different intensities and temperatures. The displacement of chloride ions at five different locations in the model reflected the detailed anion-conduction pathway, and the activity-related key residues—Cys105, Ser60, Gln224, and Phe90—were identified by mutation assays and spectroscopy. Comparisons with other proteins, including a closely related outward sodium ion pump, revealed key motifs and provided structural insights into light-driven ion transport across membranes by the NQ subfamily of rhodopsins. Unexpectedly, the response of the retinal in NM-R3 to photostimulation appears to be substantially different from that seen in bacteriorhodopsin.