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Purification of the M. magneticum Strain AMB-1 Magnetosome Associated Protein MamAΔ41
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Published on: March 25, 2010

The presumptive magnetosome protein Mms16 is a poly(3-hydroxybutyrate) granule-bound protein (phasin) in

Daniel Schultheiss1, René Handrick, Dieter Jendrossek

  • 1Max Planck Institute for Marine Microbiology, Celsiusstr. 1, 28359 Bremen, Germany. dschuele@mpi-bremen.de

Journal of Bacteriology
|March 19, 2005
PubMed

Insights

The Mms16 protein in Magnetospirillum gryphiswaldense is a polyhydroxybutyrate (PHB) granule-bound protein, not essential for magnetosome formation. It functions as a phasin, activating PHB depolymerization, and should be renamed ApdA.

Area of Science:

  • Microbiology
  • Biochemistry
  • Cell Biology

Background:

  • Mms16 protein was previously thought to be magnetosome-specific in Magnetospirillum.
  • Its proposed function involved GTPase activity in magnetosome membrane vesicle formation.

Purpose of the Study:

  • To clarify the function of the Mms16 protein in Magnetospirillum gryphiswaldense.
  • To investigate its role in magnetosome formation and other cellular processes.

Main Methods:

  • Insertion-duplication mutagenesis of the mms16 gene.
  • Complementation studies using Rhodospirillum rubrum phasin ApdA.
  • Fluorescent protein fusions (EGFP, EYFP) for in vivo localization.
  • Cell fractionation and Western blot analysis.

Main Results:

  • Mms16 mutation affected poly(3-hydroxybutyrate) (PHB) depolymerization but not magnetosome formation.
  • Mms16 functionally complemented ApdA, a known PHB granule-bound protein.
  • Mms16 localized to PHB granules, not magnetosomes, in vivo.
  • Mms16 acts as an activator of PHB hydrolysis in vitro.

Conclusions:

  • Mms16 is a PHB granule-bound protein (phasin) in M. gryphiswaldense, not essential for magnetosome formation.
  • Previous magnetosome association was likely an artifact.
  • Mms16 activates PHB depolymerization and should be renamed ApdA.

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