title: A magnetosome-associated cytochrome MamP is critical for magnetite crystal growth during the exponential growth phase.
abstract: Magnetotactic bacteria use a specific set of conserved proteins to biomineralize crystals of magnetite or greigite within their cells in organelles called magnetosomes. Using Magnetospirillum magneticum AMB-1, we examined one of the magnetotactic bacteria-specific conserved proteins named MamP that was recently reported as a new type of cytochrome c that has iron oxidase activity. We found that MamP is a membrane-bound cytochrome, and the MamP content increases during the exponential growth phase compared to two other magnetosome-associated proteins on the same operon, MamA and MamK. To assess the function of MamP, we overproduced MamP from plasmids in wild-type (WT) AMB-1 and found that during the exponential phase of growth, these cells contained more magnetite crystals that were the same size as crystals in WT cells. Conversely, when the heme c-binding motifs within the mamP on the plasmid was mutated, the cells produced the same number of crystals, but smaller crystals than in WT cells during exponential growth. These results strongly suggest that during the exponential phase of growth, MamP is crucial to the normal growth of magnetite crystals during biomineralization.
authors.affiliation: School of Natural System, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa, Japan; Bio-AFM Frontier Research Center, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa, Japan.
authors.forename: Azuma
authors.initials: A
authors.lastname: Taoka
authors.forename: Yukako
authors.initials: Y
authors.lastname: Eguchi
authors.forename: Shingo
authors.initials: S
authors.lastname: Mise
authors.forename: Zachery
authors.initials: Z
authors.lastname: Oestreicher
authors.forename: Fumio
authors.initials: F
authors.lastname: Uno
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fukumori
mesh_terms: D003460:Crystallization; D003580:Cytochromes / Q000378:metabolism*; D052203:Ferrosoferric Oxide / Q000378:metabolism*; D055944:Magnetosomes / Q000378:metabolism*; D042201:Magnetospirillum / Q000201:enzymology* / Q000378:metabolism*; D010957:Plasmids
chemical_list: D003580:Cytochromes; D052203:Ferrosoferric Oxide
keywords: Magnetospirillum magneticum AMB-1; bacterial organelle; biomineralization; heme c; iron; magnetic particle