Bacterial intermediate filaments: in vivo assembly, organization, and dynamics of crescentin.
Crescentin, which is the founding member of a rapidly growing family of bacterial cytoskeletal proteins, was previously proposed to resemble eukaryotic intermediate filament (IF) proteins based on structural prediction and in vitro polymerization properties. Here, we demonstrate that crescentin also shares in vivo properties of assembly and dynamics with IF proteins by forming stable filamentous structures that continuously incorporate subunits along their length and that grow in a nonpolar fashion. De novo assembly of crescentin is biphasic and involves a cell size-dependent mechanism that controls the length of the structure by favoring lateral insertion of crescentin subunits over bipolar longitudinal extension when the structure ends reach the cell poles. The crescentin structure is stably anchored to the cell envelope, and this cellular organization requires MreB function, identifying a new function for MreB and providing a parallel to the role of actin in IF assembly and organization in metazoan cells. Additionally, analysis of an MreB localization mutant suggests that cell wall insertion during cell elongation normally occurs along two helices of opposite handedness, each counterbalancing the other's torque.
Charbon
Godefroid
G
Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA.
Cabeen
Matthew T
MT
Jacobs-Wagner
Christine
C
D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D016935:Caulobacter crescentus / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology; D002701:Chloramphenicol / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D007382:Intermediate Filaments / Q000378:metabolism*; D009154:Mutation; D055503:Protein Multimerization / Q000187:drug effects; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology
D001426:Bacterial Proteins; D003598:Cytoskeletal Proteins; D029968:Escherichia coli Proteins; D011500:Protein Synthesis Inhibitors; C078473:MreB protein, E coli; D002701:Chloramphenicol