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Crystallographic analysis and phasing of iron‐assimilating protein 1 (FEA1) from Chlamydomonas reinhardtii
Author(s) -
Juniar Linda,
Adlfar Vida,
Hippler Michael,
Tanaka Hideaki,
Kurisu Genji
Publication year - 2021
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 37
ISSN - 2053-230X
DOI - 10.1107/s2053230x21003952
Subject(s) - chlamydomonas reinhardtii , chlamydomonas , protein crystallization , periplasmic space , chemistry , protein data bank , photosynthesis , crystallography , biochemistry , deinococcus radiodurans , protein structure , biophysics , biology , crystallization , mutant , gene , escherichia coli , organic chemistry
As an essential component of protein cofactors, iron is important for all photosynthetic organisms. In Chlamydomonas reinhardtii , iron levels are strictly controlled by proteins such as iron‐assimilating protein 1 (FEA1). This periplasmic protein is expressed under conditions of iron deficiency, but its mechanisms of function remain unknown. Because FEA1 has no amino‐acid similarity to protein structures in the Protein Data Bank, its crystal structure cannot be solved by molecular replacement. Here, recombinant FEA1 protein lacking the N‐terminal signal sequence was successfully purified and crystals of apo FEA1 were obtained by hanging‐drop vapor diffusion. Neither selenomethionine substitution nor heavy‐atom derivatization was successful; therefore, the phase problem of FEA1 crystals was solved by the native sulfur SAD method using long‐wavelength X‐rays (2.7 Å). Laser‐cutting technology was used to increase the signal‐to‐noise ratio and derive an initial structure. This study will lead to further structural studies of FEA1 to understand its function and its links to the iron‐assimilation pathway.