1GV3

The 2.0 Angstrom resolution structure of the catalytic portion of a cyanobacterial membrane-bound manganese superoxide dismutase

Summary for 1GV3

• Entry DOI: 10.2210/pdb1gv3/pdb
• Descriptor: MANGANESE SUPEROXIDE DISMUTASE, MANGANESE (II) ION (3 entities in total)
• Functional Keywords: manganese superoxide dismutase, anabaena pcc 7120
• Biological source: ANABAENA SP.
• Total number of polymer chains: 2
• Total formula weight: 56535.96

Authors

Atzenhofer, W.,Regelsberger, G.,Jacob, U.,Huber, R.,Peschek, G.A.,Obinger, C. (deposition date: 2002-02-05, release date: 2002-08-08, Last modification date: 2023-12-13)

Primary citation

Atzenhofer, W.,Regelsberger, G.,Jacob, U.,Peschek, G.A.,Furtmuller, P.,Huber, R.,Obinger, C.
The 2.0A Resolution Structure of the Catalytic Portion of a Cyanobacterial Membrane-Bound Manganese Superoxide Dismutase
J.Mol.Biol., 321:479-, 2002

PubMed Abstract: Cyanobacteria are shown to be unique in containing membrane-bound manganese superoxide dismutases (MnSOD). They are homodimeric type 2 membrane proteins that protect this phototrophic organism against oxidative stress. We have determined, for the first time, the 2.0A resolution structure of the catalytic portion of the MnSOD from the filamentous cyanobacterium Anabaena PCC 7120. Within each subunit, both the N-terminal helical hairpin (His94 and His145) and the C-terminal alpha/beta domain (His232 and Asp228) contribute ligands to the catalytic manganese site. Together with a water or hydroxide ion (OH(x)) a five-coordinated trigonal bipyramidal geometry is formed, with OH(x) and His90 forming the axial ligands and manganese shifted out of the equatorial plane in the direction of OH(x). The ligands including OH(x) are tightly constrained by hydrogen bonding with surrounding residues either from the same monomer (Tyr98, Asn144, Trp194, Gln213, Val229, Trp230) or from the neighbouring subunit (Glu231, Tyr235). This underlines the important role of the symmetric dimeric structure of MnSODs in contributing elements to both the active site and the substrate funnel. The Mn cdots, three dots, centered Mn distance (18.4A) is bridged by the hydrogen-bonded His232 of one monomer with Glu231 of the other monomer. A detailed discussion of the structure, a comparison with known structures of soluble MnSODs as well as a model of the cyanobacterial membrane-bound MnSOD is presented.

PubMed: 12162960
DOI: 10.1016/S0022-2836(02)00624-1

Experimental method

X-RAY DIFFRACTION (2 Å)