Molecular structures reveal the origin of spectral variation in cryptophyte light harvesting antenna proteins
- Univ. of New South Wales, Sydney, NSW (Australia)
- Univ. of New South Wales, Sydney, NSW (Australia); Australian Nuclear Science and Technology Organisation (ANSTO), Clayton, VIC (Australia). Australian Synchrotron
- Univ. of British Columbia, Vancouver, BC (Canada)
- Univ. of Cologne (Germany)
- Macquarie Univ., NSW (Australia)
In addition to their membrane-bound chlorophyll a/c light-harvesting antenna, the cryptophyte algae have evolved a unique phycobiliprotein antenna system located in the thylakoid lumen. The basic unit of this antenna consists of two copies of an αβ protomer where the α and β subunits scaffold different combinations of a limited number of linear tetrapyrrole chromophores. While the β subunit is highly conserved, encoded by a single plastid gene, the nuclear-encoded α subunits have evolved diversified multigene families. It is still unclear how this sequence diversity results in the spectral diversity of the mature proteins. By careful examination of three newly determined crystal structures in comparison with three previously obtained, we show how the α subunit amino acid sequences control chromophore conformations and hence spectral properties even when the chromophores are identical. Previously we have shown that α subunits control the quaternary structure of the mature αβ.αβ complex (either open or closed), however, each species appeared to only harbor a single quaternary form. Here we show that species of the Hemiselmis genus contain expressed α subunit genes that encode both distinct quaternary structures. Finally, we have discovered a common single-copy gene (expressed into protein) consisting of tandem copies of a small α subunit that could potentially scaffold pairs of light harvesting units. Together, our results show how the diversity of the multigene α subunit family produces a range of mature cryptophyte antenna proteins with differing spectral properties, and the potential for minor forms that could contribute to acclimation to varying light regimes.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
- Sponsoring Organization:
- National Institute of General Medical Sciences (NIGMS); National Institutes of Health (NIH); US Air Force Office of Scientific Research (AFOSR); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF); USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- AC02-06CH11357; AC02-76SF00515
- OSTI ID:
- 2471699
- Journal Information:
- Protein Science, Journal Name: Protein Science Journal Issue: 3 Vol. 32; ISSN 0961-8368
- Publisher:
- Wiley -- The Protein SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Controllable Phycobilin Modification: An Alternative Photoacclimation Response in Cryptophyte Algae
Cryo-EM structures of light-harvesting 2 complexes from Rhodopseudomonas palustris reveal the molecular origin of absorption tuning
Journal Article
·
Tue Feb 08 19:00:00 EST 2022
· ACS Central Science
·
OSTI ID:1982013
Cryo-EM structures of light-harvesting 2 complexes from Rhodopseudomonas palustris reveal the molecular origin of absorption tuning
Journal Article
·
Sun Oct 16 20:00:00 EDT 2022
· Proceedings of the National Academy of Sciences of the United States of America
·
OSTI ID:1893223