Journal: Elife / Year: 2016 Title: Crenactin forms actin-like double helical filaments regulated by arcadin-2. Authors: Thierry Izoré / Danguole Kureisaite-Ciziene / Stephen H McLaughlin / Jan Löwe / Abstract: The similarity of eukaryotic actin to crenactin, a filament-forming protein from the crenarchaeon supports the theory of a common origin of Crenarchaea and Eukaryotes. Monomeric structures of ...The similarity of eukaryotic actin to crenactin, a filament-forming protein from the crenarchaeon supports the theory of a common origin of Crenarchaea and Eukaryotes. Monomeric structures of crenactin and actin are similar, although their filament architectures were suggested to be different. Here we report that crenactin forms double helical filaments that show exceptional similarity to eukaryotic F-actin. With cryo-electron microscopy and helical reconstruction we solved the structure of the crenactin filament to 3.8 Å resolution. When forming double filaments, the 'hydrophobic plug' loop in crenactin rearranges. Arcadin-2, also encoded by the arcade gene cluster, binds tightly with its C-terminus to the hydrophobic groove of crenactin. Binding is reminiscent of eukaryotic actin modulators such as cofilin and thymosin β4 and arcadin-2 is a depolymeriser of crenactin filaments. Our work further supports the theory of shared ancestry of Eukaryotes and Crenarchaea.
Resolution: 2→2.11 Å / Redundancy: 19.7 % / Rmerge(I) obs: 1.348 / Mean I/σ(I) obs: 2.3 / CC1/2: 0.903 / % possible all: 100
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Processing
Software
Name
Version
Classification
REFMAC
5.8.0151
refinement
SCALA
datascaling
PHASER
phasing
Refinement
Method to determine structure: SIRAS / Resolution: 2→30 Å / Cor.coef. Fo:Fc: 0.957 / Cor.coef. Fo:Fc free: 0.957 / SU B: 4.37 / SU ML: 0.115 / Cross valid method: THROUGHOUT / ESU R: 0.139 / ESU R Free: 0.128 / Details: HYDROGENS HAVE BEEN USED IF PRESENT IN THE INPUT
Rfactor
Num. reflection
% reflection
Selection details
Rfree
0.23032
472
5.2 %
RANDOM
Rwork
0.20844
-
-
-
obs
0.20961
8598
99.93 %
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Solvent computation
Ion probe radii: 0.8 Å / Shrinkage radii: 0.8 Å / VDW probe radii: 1.4 Å