Deletion of the ftsZ-like Gene Results in the Production of Superparamagnetic Magnetite Magnetosomes in Magnetospirillum gryphiswaldense.

En las bacterias magnetotácticas hay dos genes: uno que codifican para la proteína de división celualr FtsZ y otro gen que codifica para una proteína similar a FtsZ. Esta segunda proteína similar a FtsZ está implicada en la formación de magnetosomas



Deletion of the ftsZ-like Gene Results in the Production of Superparamagnetic Magnetite Magnetosomes in Magnetospirillum gryphiswaldense.

J Bacteriol. 2009 Dec 18;

Authors: Ding Y, Li J, Liu J, Yang J, Jiang W, Tian J, Li Y, Pan Y, Li J

Magnetotactic bacteria (MTB) synthesize unique organelles termed 'magnetosomes', which are membrane-enclosed structures containing crystals of magnetite or greigite. Magnetosomes form a chain around MamK cytoskeletal filaments, and provide the basis for the ability of MTB to navigate along geomagnetic field lines, to find optimal microaerobic habitats. Genomes of species of the MTB genus Magnetospirillum, in addition to a gene encoding the tubulin-like FtsZ protein (involved in cell division), contain a second gene termed 'ftsZ-like', whose function is unknown. In the present study, we found that the ftsZ-like gene of M. gryphiswaldense strain MSR-1 belongs to 4.9-kb mamXY polycistronic transcription unit. We then purified recombinant FtsZ-like protein to homogeneity. FtsZ-like efficiently hydrolyzed ATP and GTP, with ATPase and GTPase activities of 2.17 and 5.56 mumol phosphorus per mol protein per min respectively. FtsZ-like underwent GTP-dependent polymerization into long filamentous bundles in vitro. To determine the role of ftsZ-like, we constructed a mutant of ftsZ-like (DeltaftsZ-like), and its complementation strain (DeltaftsZ-like_C). Growth of DeltaftsZ-like cells was similar to that of wild-type, indicating that DeltaftsZ-like gene is not involved in cell division. Transmission electron microscopic observations indicated that the DeltaftsZ-like cells, in comparison to wild-type, produced smaller magnetosomes, with poorly-defined morphology, and irregular alignment including large gaps. Magnetic analyses showed that DeltaftsZ-like produced mainly superparamagnetic (SP) magnetite particles, whereas wide-type and DeltaftsZ-like_C cells produced mainly single-domain (SD) particles. Our findings suggest that the FtsZ-like protein is required for synthesis of SD particles and of magnetosomes in M. gryphiswaldense.