Nucleotide‐independent cytoskeletal scaffolds in bacteria

Abstract

Bacteria possess a diverse set of cytoskeletal proteins that mediate key cellular processes such as morphogenesis, cell division, DNA segregation, and motility. Similar to eukaryotic actin or tubulin, many of them require nucleotide binding and hydrolysis for proper polymerization and function. However, there is also a growing number of bacterial cytoskeletal elements that assemble in a nucleotide-independent manner, including intermediate filament-like structures as well several classes of bacteria-specific polymers. The members of this group form stable scaffolds that have architectural roles or act as localization factors recruiting other proteins to distinct positions within the cell. Here, we highlight the elements that constitute the nucleotideindependent cytoskeleton of bacteria and discuss their biological functions in different species. V C 2013 Wiley Periodicals, Inc.

A Comparative Quantitative Proteomic Study Identifies New Proteins Relevant for Sulfur Oxidation in the Purple Sulfur Bacterium Allochromatium vinosum

“…The coiled coil is a protein motif characterized by superhelical twisting of two or more alpha helices around one another. Coiled-coil proteins can form rod-like tertiary structures and include the intermediate filaments of the metazoan cytoskeleton, as well as bacterium-specific cytoskeletal proteins that typically assemble into stable macromolecular scaffolds (70,71). Taken together, the exclusive detection in the A. vinosum sulfur globule proteome and the properties predicted from the sequence strongly indicate that Alvin_2515 is a new protein of the sulfur globule envelope, which we term SgpD (Fig.…”

β-Helical architecture of cytoskeletal bactofilin filaments revealed by solid-state NMR

“…This behavior is reminiscent of IFs, although there is no evolutionary relationship between these two groups of cytoskeletal elements (6). In particular, bactofilins lack predicted coiled-coil regions, which are a key feature of IF proteins.…”

“…Various studies proved the existence of bacterial homologs of eukaryotic cytoskeleton proteins including tubulin homologs such as FtsZ (1), actin homologs such as MreB (2), and intermediate filament (IF)-like proteins (3), which together have important roles in cell division, morphogenesis, polarity determination, and DNA segregation (4)(5)(6)(7). In addition, several groups of polymer-forming proteins that are limited to the bacterial domain have been described (6).…”

The Variable Internal Structure of the Mycoplasma penetrans Attachment Organelle Revealed by Biochemical and Microscopic Analyses: Implications for Attachment Organelle Mechanism and Evolution

“…In contrast to the highly dynamic MreB and FtsZ, many of these proteins form static structures. The ␣-helical coiled-coil-rich, intermediate filament-like protein crescentin from C. crescentus is associated with the establishment of cell shape (18,19). Many bacterial scaffold proteins contain an abundance of coiled-coil domains, which are important for oligomerization and close protein-protein interactions and are referred to as coiled-coil-rich proteins (CCRPs) (reviewed in reference 20).…”

“…The widely distributed bactofilins are characterized by the conserved DUF583 domain and form stable nucleotideindependent filaments that serve as spatial landmarks (21,22). Other bacterial cytoskeletal proteins include DivIVA and PopZ, which assemble into 2-or 3-dimensional arrays at extant or nascent cell poles and interact with proteins involved in poleassociated processes (reviewed in reference 19). It is essential to understand processes that rely on bacterial cell polarization, and this understanding can be achieved by establishing an inventory of cytoskeletal proteins across bacterial phylogeny and determining their characteristics and how these properties enable them to carry out their functions.…”