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Purification of the M. magneticum Strain AMB-1 Magnetosome Associated Protein MamAΔ41
Published on: March 25, 2010
Inter-phylum structural conservation of the magnetosome-associated TPR-containing protein, MamA
Natalie Zeytuni1, Dror Baran, Geula Davidov
1Department of Life Sciences, Ben Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel.
Abstract:
Magnetotactic bacteria enclose the magnetosome, a unique prokaryotic sub-cellular organelle that allows the biomineralization of magnetic nano-crystals. Membrane-coated magnetosomes are arranged into a linear chain that permits magnetotactic bacteria to navigate geomagnetic fields. Magnetosome assembly and biomineralization are controlled by conserved magnetosome-associated proteins, including MamA, a tetra-trico-peptide repeat (TPR)-containing protein that was shown to coat the magnetosome membrane. In this study, two MamA structures from Candidatus Magnetobacterium bavaricum (Mbav) were determined via X-ray crystallography. These structures confirm that Mbav MamA folds as a sequential TPR protein and shares a high degree of structural similarity with homologous MamA proteins from Magnetospirillum species. Furthermore, the two TPR-containing domains of MamA are separated by an interphylum-conserved region containing a flexible hinge that is involved in ligand binding and recognition. Finally, substantial differences were found in the local stabilization of the MamA N-terminal domain as a result of the loss of an evolutionary conserved salt bridge.
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