Structure of the magnetosome-associated actin-like MamK filament at subnanometer resolution

TY - JOUR

T1 - Structure of the magnetosome-associated actin-like MamK filament at subnanometer resolution

AU - Bergeron, Julien R C

AU - Hutto, Rachel

AU - Ozyamak, Ertan

AU - Hom, Nancy

AU - Hansen, Jesse

AU - Draper, Olga

AU - Byrne, Meghan E

AU - Keyhani, Sepehr

AU - Komeili, Arash

AU - Kollman, Justin M

N1 - © 2016 The Protein Society.

PY - 2017/1

Y1 - 2017/1

N2 - Magnetotactic bacteria possess cellular compartments called magnetosomes that sense magnetic fields. Alignment of magnetosomes in the bacterial cell is necessary for their function, and this is achieved through anchoring of magnetosomes to filaments composed of the protein MamK. MamK is an actin homolog that polymerizes upon ATP binding. Here, we report the structure of the MamK filament at ∼6.5 Å, obtained by cryo-Electron Microscopy. This structure confirms our previously reported double-stranded, nonstaggered architecture, and reveals the molecular basis for filament formation. While MamK is closest in sequence to the bacterial actin MreB, the longitudinal contacts along each MamK strand most closely resemble those of eukaryotic actin. In contrast, the cross-strand interface, with a surprisingly limited set of contacts, is novel among actin homologs and gives rise to the nonstaggered architecture.

AB - Magnetotactic bacteria possess cellular compartments called magnetosomes that sense magnetic fields. Alignment of magnetosomes in the bacterial cell is necessary for their function, and this is achieved through anchoring of magnetosomes to filaments composed of the protein MamK. MamK is an actin homolog that polymerizes upon ATP binding. Here, we report the structure of the MamK filament at ∼6.5 Å, obtained by cryo-Electron Microscopy. This structure confirms our previously reported double-stranded, nonstaggered architecture, and reveals the molecular basis for filament formation. While MamK is closest in sequence to the bacterial actin MreB, the longitudinal contacts along each MamK strand most closely resemble those of eukaryotic actin. In contrast, the cross-strand interface, with a surprisingly limited set of contacts, is novel among actin homologs and gives rise to the nonstaggered architecture.

KW - Bacterial Proteins/metabolism

KW - Magnetosomes/metabolism

KW - Magnetospirillum/metabolism

KW - Multiprotein Complexes/metabolism

U2 - 10.1002/pro.2979

DO - 10.1002/pro.2979

M3 - Article

C2 - 27391173

SN - 0961-8368

VL - 26

SP - 93

EP - 102

JO - Protein science

JF - Protein science

IS - 1

ER -