1RFK

Crystal Structure of 2Fe2S Ferredoxin from Thermophilic Cyanobacterium Mastigocladus Laminosus

Summary for 1RFK

• Entry DOI: 10.2210/pdb1rfk/pdb
• Related: 1a70 1off 1qt9 4fxc
• Descriptor: Ferredoxin, FE2/S2 (INORGANIC) CLUSTER (3 entities in total)
• Functional Keywords: ferredoxin, thermostability, electron transport
• Biological source: Mastigocladus laminosus
• Total number of polymer chains: 2
• Total formula weight: 21596.89

Authors

Fish, A.,Nechushtai, R.,Livnah, O. (deposition date: 2003-11-10, release date: 2005-04-12, Last modification date: 2024-02-14)

Primary citation

Fish, A.,Danieli, T.,Ohad, I.,Nechushtai, R.,Livnah, O.
Structural basis for the thermostability of ferredoxin from the cyanobacterium Mastigocladus laminosus.
J.Mol.Biol., 350:599-608, 2005

PubMed Abstract: Plant-type ferredoxins (Fds) carry a single [2Fe-2S] cluster and serve as electron acceptors of photosystem I (PSI). The ferredoxin from the thermophilic cyanobacterium Mastigocladus laminosus displays optimal activity at 65 degrees C. In order to reveal the molecular factors that confer thermostability, the crystal structure of M.laminosus Fd (mFd) was determined to 1.25 A resolution and subsequently analyzed in comparison with four similar plant-type mesophilic ferredoxins. The topologies of the plant-type ferredoxins are similar, yet two structural determinants were identified that may account for differences in thermostability, a salt bridge network in the C-terminal region, and the flexible L1,2 loop that increases hydrophobic accessible surface area. These conclusions were verified by three mutations, i.e. substitution of L1,2 into a rigid beta-turn ((Delta)L1,2) and two point mutations (E90S and E96S) that disrupt the salt bridge network at the C-terminal region. All three mutants have shown reduced electron transfer (ET) capabilities and [2Fe-2S] stability at high temperatures in comparison to the wild-type mFd. The results have also provided new insights into the involvement of the L1,2 loop in the Fd interactions with its electron donor, the PSI complex.

PubMed: 15961101
DOI: 10.1016/j.jmb.2005.04.071

Experimental method

X-RAY DIFFRACTION (1.25 Å)