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5ljw

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MamK non-polymerising A278D mutant bound to AMPPNPMamK non-polymerising A278D mutant bound to AMPPNP

Structural highlights

5ljw is a 2 chain structure with sequence from Magnetospirillum magneticum AMB-1. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 1.8Å
Ligands:,
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

MAMK_MAGSA Protein with ATPase activity which forms dynamic cytoplasmic filaments (probably with paralog MamK-like) that organize magnetosomes into long chains running parallel to the long axis of the cell (Probable) (PubMed:21883528, PubMed:28790202, PubMed:23204522, PubMed:24957623). Turnover of MamK filaments is probably promoted by MamK-like, which provides a monomer pool (PubMed:24957623). Forms twisted filaments in the presence of ATP or GTP (PubMed:20161777, PubMed:23204522, PubMed:27391173). Serves to close gaps between magnetosomes in the chain (PubMed:26884433). Interaction with MCP10 is involved in controlling the response to magnetic fields, possibly by controlling flagellar rotation (PubMed:20471399). Expression in E.coli yields a filament in the cell's longitudinal axis; the protein nucleates at several sites and one extremity of the filament is located at the cell pole (PubMed:17085581, PubMed:20161777).[1] [2] [3] [4] [5] [6] [7] [8] [9] [10]

Publication Abstract from PubMed

Magnetotactic bacteria produce iron-rich magnetic nanoparticles that are enclosed by membrane invaginations to form magnetosomes so they are able to sense and act upon Earth's magnetic field. In Magnetospirillum and other magnetotactic bacteria, to combine their magnetic moments, magnetosomes align along filaments formed by a bacterial actin homolog, MamK. Here, we present the crystal structure of a nonpolymerizing mutant of MamK from Magnetospirillum magneticum AMB-1 at 1.8-A resolution, revealing its close similarity to actin and MreB. The crystals contain AMPPNP-bound monomeric MamK in two different conformations. To investigate conformational changes associated with polymerization, we used unmodified MamK protein and cryo-EM with helical 3D reconstruction in RELION to obtain a density map and a fully refined atomic model of MamK in filamentous form at 3.6-A resolution. The filament is parallel (polar) double-helical, with a rise of 52.2 A and a twist of 23.8 degrees . As shown previously and unusually for actin-like filaments, the MamK subunits from each of the two strands are juxtaposed, creating an additional twofold axis along the filament. Compared with monomeric MamK, ADP-bound MamK in the filament undergoes a conformational change, rotating domains I and II against each other to further close the interdomain cleft between subdomains IB and IIB. The domain movement causes several loops to close around the nucleotide-binding pocket. Glu-143, a key residue for catalysis coordinating the magnesium ion, moves closer, presumably switching nucleotide hydrolysis upon polymerization-one of the hallmarks of cytomotive filaments of the actin type.

X-ray and cryo-EM structures of monomeric and filamentous actin-like protein MamK reveal changes associated with polymerization.,Lowe J, He S, Scheres SH, Savva CG Proc Natl Acad Sci U S A. 2016 Nov 22;113(47):13396-13401. Epub 2016 Nov 7. PMID:27821762[11]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

  1. ↑ Pradel N, Santini CL, Bernadac A, Fukumori Y, Wu LF. Biogenesis of actin-like bacterial cytoskeletal filaments destined for positioning prokaryotic magnetic organelles. Proc Natl Acad Sci U S A. 2006 Nov 14;103(46):17485-9. PMID:17085581 doi:10.1073/pnas.0603760103
  2. ↑ Rioux JB, Philippe N, Pereira S, Pignol D, Wu LF, Ginet N. A second actin-like MamK protein in Magnetospirillum magneticum AMB-1 encoded outside the genomic magnetosome island. PLoS One. 2010 Feb 10;5(2):e9151. PMID:20161777 doi:10.1371/journal.pone.0009151
  3. ↑ Philippe N, Wu LF. An MCP-like protein interacts with the MamK cytoskeleton and is involved in magnetotaxis in Magnetospirillum magneticum AMB-1. J Mol Biol. 2010 Jul 16;400(3):309-22. PMID:20471399 doi:10.1016/j.jmb.2010.05.011
  4. ↑ Draper O, Byrne ME, Li Z, Keyhani S, Barrozo JC, Jensen G, Komeili A. MamK, a bacterial actin, forms dynamic filaments in vivo that are regulated by the acidic proteins MamJ and LimJ. Mol Microbiol. 2011 Oct;82(2):342-54. PMID:21883528 doi:10.1111/j.1365-2958.2011.07815.x
  5. ↑ Ozyamak E, Kollman J, Agard DA, Komeili A. The bacterial actin MamK: in vitro assembly behavior and filament architecture. J Biol Chem. 2013 Feb 8;288(6):4265-77. PMID:23204522 doi:10.1074/jbc.M112.417030
  6. ↑ Abreu N, Mannoubi S, Ozyamak E, Pignol D, Ginet N, Komeili A. Interplay between two bacterial actin homologs, MamK and MamK-Like, is required for the alignment of magnetosome organelles in Magnetospirillum magneticum AMB-1. J Bacteriol. 2014 Sep;196(17):3111-21. PMID:24957623 doi:10.1128/JB.01674-14
  7. ↑ Cornejo E, Subramanian P, Li Z, Jensen GJ, Komeili A. Dynamic Remodeling of the Magnetosome Membrane Is Triggered by the Initiation of Biomineralization. mBio. 2016 Feb 16;7(1):e01898-15. PMID:26884433 doi:10.1128/mBio.01898-15
  8. ↑ Bergeron JR, Hutto R, Ozyamak E, Hom N, Hansen J, Draper O, Byrne ME, Keyhani S, Komeili A, Kollman JM. Structure of the Magnetosome-associated actin-like MamK filament at sub-nanometer resolution. Protein Sci. 2016 Jul 8. doi: 10.1002/pro.2979. PMID:27391173 doi:http://dx.doi.org/10.1002/pro.2979
  9. ↑ Taoka A, Kiyokawa A, Uesugi C, Kikuchi Y, Oestreicher Z, Morii K, Eguchi Y, Fukumori Y. Tethered Magnets Are the Key to Magnetotaxis: Direct Observations of Magnetospirillum magneticum AMB-1 Show that MamK Distributes Magnetosome Organelles Equally to Daughter Cells. mBio. 2017 Aug 8;8(4):e00679-17. PMID:28790202 doi:10.1128/mBio.00679-17
  10. ↑ Komeili A, Li Z, Newman DK, Jensen GJ. Magnetosomes are cell membrane invaginations organized by the actin-like protein MamK. Science. 2006 Jan 13;311(5758):242-5. PMID:16373532 doi:10.1126/science.1123231
  11. ↑ Lowe J, He S, Scheres SH, Savva CG. X-ray and cryo-EM structures of monomeric and filamentous actin-like protein MamK reveal changes associated with polymerization. Proc Natl Acad Sci U S A. 2016 Nov 22;113(47):13396-13401. Epub 2016 Nov 7. PMID:27821762 doi:http://dx.doi.org/10.1073/pnas.1612034113

5ljw, resolution 1.80Å

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