Back to Search
Start Over
Archaeal actin from a hyperthermophile forms a single-stranded filament
- Source :
- Proceedings of the National Academy of Sciences. 112:9340-9345
- Publication Year :
- 2015
- Publisher :
- Proceedings of the National Academy of Sciences, 2015.
-
Abstract
- The prokaryotic origins of the actin cytoskeleton have been firmly established, but it has become clear that the bacterial actins form a wide variety of different filaments, different both from each other and from eukaryotic F-actin. We have used electron cryomicroscopy (cryo-EM) to examine the filaments formed by the protein crenactin (a crenarchaeal actin) from Pyrobaculum calidifontis, an organism that grows optimally at 90 °C. Although this protein only has ∼ 20% sequence identity with eukaryotic actin, phylogenetic analyses have placed it much closer to eukaryotic actin than any of the bacterial homologs. It has been assumed that the crenactin filament is double-stranded, like F-actin, in part because it would be hard to imagine how a single-stranded filament would be stable at such high temperatures. We show that not only is the crenactin filament single-stranded, but that it is remarkably similar to each of the two strands in F-actin. A large insertion in the crenactin sequence would prevent the formation of an F-actin-like double-stranded filament. Further, analysis of two existing crystal structures reveals six different subunit-subunit interfaces that are filament-like, but each is different from the others in terms of significant rotations. This variability in the subunit-subunit interface, seen at atomic resolution in crystals, can explain the large variability in the crenactin filaments observed by cryo-EM and helps to explain the variability in twist that has been observed for eukaryotic actin filaments.
- Subjects :
- Models, Molecular
Protein Conformation
Cryo-electron microscopy
Molecular Sequence Data
Arp2/3 complex
Sequence (biology)
macromolecular substances
Protein filament
Commentaries
Computer Simulation
Amino Acid Sequence
Cytoskeleton
Phylogeny
Actin
Alanine
Multidisciplinary
Sequence Homology, Amino Acid
biology
Cryoelectron Microscopy
Computational Biology
Hydrogen-Ion Concentration
Actin cytoskeleton
Actins
Recombinant Proteins
Sequence identity
Hyperthermophile
Cell biology
Actin Cytoskeleton
Pyrobaculum
biology.protein
Software
Protein Binding
Subjects
Details
- ISSN :
- 10916490 and 00278424
- Volume :
- 112
- Database :
- OpenAIRE
- Journal :
- Proceedings of the National Academy of Sciences
- Accession number :
- edsair.doi.dedup.....0a6aeec643f1757a71b7de75f78fc2cf