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The PufX quinone channel enables the light‐harvesting 1 antenna to bind more carotenoids for light collection and photoprotection
Author(s) -
Olsen John D.,
Martin Elizabeth C.,
Hunter C. Neil
Publication year - 2017
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.12575
Subject(s) - photoprotection , rhodobacter sphaeroides , photosynthesis , photosynthetic reaction centre , chemistry , biophysics , photochemistry , carotenoid , photosystem ii , botany , biology , biochemistry
Photosynthesis in some phototrophic bacteria requires the PufX component of the reaction centre–light‐harvesting 1–PufX ( RC ‐ LH 1‐PufX) complex, which creates a pore for quinone/quinol (Q/ QH 2 ) exchange across the LH 1 barrier surrounding the RC . However, photosynthetic bacteria such as Thermochromatium (T.) tepidum do not require PufX because there are fewer carotenoid binding sites, which creates multiple pores in the LH 1 ring for Q/ QH 2 exchange. We show that an αTrp ‐24 →Phe alteration of the Rhodobacter (Rba.) sphaeroides LH 1 antenna impairs carotenoid binding and allows photosynthetic growth in the absence of PufX. We propose that acquisition of PufX and confining Q/ QH 2 traffic to a pore adjacent to the RC Q B site is an evolutionary upgrade that allows increased LH 1 carotenoid content for enhanced light absorption and photoprotection.