Bacterial Actin-Like Proteins

Petek, Natalie A.; Mullins, R. Dyche

doi:10.1016/b978-0-12-397924-7.00002-9

Cited by 5 publications

(1 citation statement)

References 23 publications

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“…Actin-like proteins are present in all domains of life [66]. Actin-like proteins have a characteristic structure of four distinct domains stabilised by an ADP molecule.…”

Section: Peptidoglycan Synthesismentioning

confidence: 99%

The evolution of spherical cell shape; progress and perspective

Yulo

Hendrickson

2019

Biochemical Society Transactions

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Bacterial cell shape is a key trait governing the extracellular and intracellular factors of bacterial life. Rod-like cell shape appears to be original which implies that the cell wall, division, and rod-like shape came together in ancient bacteria and that the myriad of shapes observed in extant bacteria have evolved from this ancestral shape. In order to understand its evolution, we must first understand how this trait is actively maintained through the construction and maintenance of the peptidoglycan cell wall. The proteins that are primarily responsible for cell shape are therefore the elements of the bacterial cytoskeleton, principally FtsZ, MreB, and the penicillin-binding proteins. MreB is particularly relevant in the transition between rod-like and spherical cell shape as it is often (but not always) lost early in the process. Here we will highlight what is known of this particular transition in cell shape and how it affects fitness before giving a brief perspective on what will be required in order to progress the field of cell shape evolution from a purely mechanistic discipline to one that has the perspective to both propose and to test reasonable hypotheses regarding the ecological drivers of cell shape change.

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“…Actin-like proteins are present in all domains of life [66]. Actin-like proteins have a characteristic structure of four distinct domains stabilised by an ADP molecule.…”

Section: Peptidoglycan Synthesismentioning

confidence: 99%

The evolution of spherical cell shape; progress and perspective

Yulo

Hendrickson

2019

Biochemical Society Transactions

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Structure and Dynamics of Actin-Like Cytomotive Filaments in Plasmid Segregation

Gayathri

Harne

2017

Prokaryotic Cytoskeletons

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One of the well-known functions of the bacterial cytoskeleton is plasmid segregation. Type II plasmid segregation systems, among the best characterized with respect to the mechanism of action, possess an actin-like cytomotive filament as the motor component. This chapter describes the essential components of the plasmid segregation machinery and their mechanism of action, concentrating on the actin-like protein family of the bacterial cytoskeleton. The structures of the actin-like filaments depend on their nucleotide state and these in turn contribute to the dynamics of the filaments. The components that link the filaments to the plasmid DNA also regulate filament dynamics. The modulation of the dynamics facilitates the cytomotive filament to function as a mitotic spindle with a minimal number of components.

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Archaeal actin from a hyperthermophile forms a single-stranded filament

Braun

Orlova

Valegård

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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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.helical polymers | variable twist | cytoskeletal filaments | crenactin A ctin is one of the most highly conserved as well as abundant eukaryotic proteins. From chickens to humans, an evolutionary separation of ∼350 million years, there are no amino acid changes in the skeletal muscle isoform of actin (1). There are at least six different mammalian isoforms that are quite similar to each other, and all seem to have diverged from a common ancestral actin gene (2). In contrast, we now know that bacteria have actin-like proteins that share a common fold (3-5) but have vanishingly little sequence similarity both among themselves and to eukaryotic actin (6).Two recent crystal structures of a crenarchaeal actin, crenactin (7, 8), raise interesting questions about the structure of the crenactin filament and its evolutionary relationship to F-actin. In both crystals (with two different space groups) crenactin forms a single-stranded filament with eight subunits per ∼420-Å righthanded turn, with a rise and rotation per subunit, therefore, of ∼53 Å and 45°, respectively. In contrast, in F-actin there is a rise and rotation of ∼55 Å and ∼27°along each of the two long-pitch right-handed strands. It was stated (9) that outside of the crystal the crenactin filaments are double-stranded, based upon the suggestion (8) that a single-stranded filament would unlikely be stable and that power spectra from crenactin filaments showed a strong layer line at ∼1/(210 Å), half of the repeat in the crystals.We have been able to ...

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Bacterial Actin-Like Proteins

Cited by 5 publications

References 23 publications

The evolution of spherical cell shape; progress and perspective

The evolution of spherical cell shape; progress and perspective

Structure and Dynamics of Actin-Like Cytomotive Filaments in Plasmid Segregation

Archaeal actin from a hyperthermophile forms a single-stranded filament

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