A Magnetosome-specific GTPase from the Magnetic Bacterium Magnetospirillum magneticum AMB-1

Yoshiko Okamura, Haruko Takeyama, Tadashi Matsunaga*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

67 Citations (Scopus)


Magnetic bacteria produce intracellular vesicles that envelope single domain magnetite crystals. Although many proteins are present in this intracellular vesicle membrane, five are specific to this membrane. A 16-kDa protein, designated Mms16, is the most abundant of the magnetosome-specific proteins, and to establish its function we cloned and sequenced its gene from Magnetospirillum magneticum AMB-1. This was achieved by determination of the N-terminal amino acid sequence of the protein following two dimensional polyacrylamide gel electrophoresis, and sequencing of the gene was performed by gene walking using anchored polymerase chain reaction. Mms16 contains a putative ATP/GTP binding motif (P-loop). Recombinant Mms16 with a hemagglutinin tag, was expressed in Escherichia coli and purified. Recombinant Mms16 protein could bind GTP and showed GTPase activity. GTP was the preferred substrate for Mms16-catalyzed nucleotide triphosphate hydrolysis. These results suggest that a novel protein specifically localized on the magnetic particle membrane, Mms16, is a GTPase. Mms16 protein showed similar characteristics to small GTPases involved in the formation of intracellular vesicles. Furthermore, addition of the GTPase inhibitor AIF4- also inhibited magnetic particle synthesis, suggesting that GTPase is required for magnetic particles synthesis.

Original languageEnglish
Pages (from-to)48183-48188
Number of pages6
JournalJournal of Biological Chemistry
Issue number51
Publication statusPublished - 2001 Dec 21
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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