Fe starvation induces a second LHCI tetramer to photosystem I in green algae

Helen W Liu; Radhika Khera; Patricia Grob; Sean D Gallaher; Samuel O Purvine; Carrie D Nicora; Mary S Lipton; Krishna K Niyogi; Eva Nogales; Masakazu Iwai; Sabeeha S Merchant

doi:10.1101/2024.12.11.624522

Fe starvation induces a second LHCI tetramer to photosystem I in green algae

bioRxiv [Preprint]. 2024 Dec 12:2024.12.11.624522. doi: 10.1101/2024.12.11.624522.

Authors

Helen W Liu¹, Radhika Khera^{1

2}, Patricia Grob^{2

3}, Sean D Gallaher³, Samuel O Purvine⁴, Carrie D Nicora⁴, Mary S Lipton⁴, Krishna K Niyogi^{1

2

5}, Eva Nogales^{2

3

5

6}, Masakazu Iwai^{1

5}, Sabeeha S Merchant^{1

3

6

7}

Affiliations

¹ Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
² Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA.
³ California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, USA.
⁴ Earth and Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
⁵ Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
⁶ Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
⁷ Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, USA, CA 94720.

Abstract

Iron (Fe) availability limits photosynthesis at a global scale where Fe-rich photosystem (PS) I abundance is drastically reduced in Fe-poor environments. We used single-particle cryo-electron microscopy to reveal a unique Fe starvation-dependent arrangement of light-harvesting chlorophyll (LHC) proteins where Fe starvation-induced TIDI1 is found in an additional tetramer of LHC proteins associated with PSI in Dunaliella tertiolecta and Dunaliella salina. These cosmopolitan green algae are resilient to poor Fe nutrition. TIDI1 is a distinct LHC protein that co-occurs in diverse algae with flavodoxin (an Fe-independent replacement for the Fe-containing ferredoxin). The antenna expansion in eukaryotic algae we describe here is reminiscent of the iron-starvation induced (isiA-encoding) antenna ring in cyanobacteria, which typically co-occurs with isiB, encoding flavodoxin. Our work showcases the convergent strategies that evolved after the Great Oxidation Event to maintain PSI capacity.

Keywords: TIDI; flavodoxin; iron homeostasis; iron starvation-induced protein A (isiA); phytoplankton; structural biology.

Publication types

Preprint

Grants and funding

R01 GM129325/GM/NIGMS NIH HHS/United States