7DDW

Crystal structure of a mutant Staphylococcus equorum manganese superoxide dismutase S126C

Summary for 7DDW

• Entry DOI: 10.2210/pdb7ddw/pdb
• Related: 5X2J 6M30
• Descriptor: Superoxide dismutase, MANGANESE (II) ION (3 entities in total)
• Functional Keywords: superoxide dismutase, staphylococcus equorum, oxidoreductase, disulfide bond
• Biological source: Staphylococcus equorum
• Total number of polymer chains: 6
• Total formula weight: 141438.18

Authors

Retnoningrum, D.S.,Yoshida, H.,Razani, M.D.,Meidianto, V.F.,Hartanto, A.,Artarini, A.,Ismaya, W.T. (deposition date: 2020-10-30, release date: 2021-04-07, Last modification date: 2024-10-30)

Primary citation

Retnoningrum, D.S.,Yoshida, H.,Razani, M.D.,Muliadi, R.,Meidianto, V.F.,Artarini, A.,Ismaya, W.T.
The role of S126 in the Staphylococcus equorum MnSOD activity and stability.
J.Struct.Biol., 213:107731-107731, 2021

PubMed Abstract: The dimeric form of manganese superoxide dismutase is instrumental for activity because each of the monomers provides amino acid residues participating in the enzymatic reaction. Hence, preventing dissociation of the dimer would maintain the enzymatic activity in detrimental conditions e.g. high temperature. To prevent dissociation of the dimer, a disulphide (S-S) bond was introduced at the dimer interface. In the wild type structure, S126 interacts with S126 of the other monomer. In the presented work, a mutant was designed with an S126C substitution. The crystal structure of the S126C mutant showed that only 50-70% of monomers formed the S-S bond. This observed imperfect S-S bonding was likely caused by photolytic S-S bond breakage mediated by the neighbouring tryptophan residue. In the wild type, S126 is located facing W163 and forms a water-mediated hydrogen bond with E164; W163 and E164 are crucial in the enzyme's activity. The replacement of S126 by a cysteine residue lowered the activity of the enzyme by ~70%. S126 has never been considered to play a role in the enzyme's activity or stability, thus the finding showed the importance of this residue.

PubMed: 33794368
DOI: 10.1016/j.jsb.2021.107731

Experimental method

X-RAY DIFFRACTION (1.88 Å)