Interplay of four auxiliary factors is required for the assembly of photosystem I reaction center subcomplex

Sreedhar Nellaepalli, Rick G. Kim, Arthur R. Grossman, Yuichiro Takahashi

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The photosystem I (PSI) complex consisting of reaction center (RC) subunits, several peripheral subunits and many co-factors, is present in the thylakoid membranes of chloroplasts and cyanobacteria. The assembly of RC subunits (PsaA/B) that bind electron transfer co-factors and antenna pigments is an intricate process, and is mediated by several auxiliary factors such as Ycf3, Y3IP1/CGL59, Ycf4 and Ycf37/PYG7/CGL71. However, their precise molecular mechanisms in RC assembly remain to be addressed. Here we purified four PSI auxiliary factors by affinity chromatography, and characterized co-purified PSI assembly intermediates. We suggest that Ycf3 assists the initial assembly of newly synthesized PsaA/B subunits into an RC subcomplex, while Y3IP1 may be involved in transferring the RC subcomplex from Ycf3 to the Ycf4 module that stabilizes it. CGL71 may form an oligomer that transiently interacts with the PSI RC subcomplex, physically protecting it under oxic conditions until association with the peripheral PSI subunits occurs. Together, our results reveal the interplay among four auxiliary factors required for the stepwise assembly of the PSI RC.

    Original languageEnglish
    Pages (from-to)1075-1086
    Number of pages12
    JournalPlant Journal
    Volume106
    Issue number4
    DOIs
    Publication statusPublished - May 2021

    Keywords

    • CGL71
    • Chlamydomonas reinhardtii
    • Y3IP1
    • Ycf3
    • Ycf4
    • photosystem I assembly

    ASJC Scopus subject areas

    • Genetics
    • Plant Science
    • Cell Biology

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