Abstract
Evolution of a nano-machine consisting of multiple parts, each with a specific function, is a complex process. A change in one part should eventually result in changes in other parts, if the overall function is to be conserved. In bacterial flagella, the filament and the hook have distinct functions and their respective proteins, FliC and FlgE, have different three-dimensional structures. The filament functions as a helical propeller and the hook as a flexible universal joint. Two proteins, FlgK and FlgL, assure a smooth connectivity between the hook and the filament. Here we show that, in Campylobacter, the 3D structure of FlgK differs from that of its orthologs in Salmonella and Burkholderia, whose structures have previously been solved. Docking the model of the FlgK junction onto the structure of the Campylobacter hook provides some clues about its divergence. These data suggest how evolutionary pressure to adapt to structural constraints, due to the structure of Campylobacter hook, causes divergence of one element of a supra-molecular complex in order to maintain the function of the entire flagellar assembly.
Highlights
Gram-positive and gram-negative bacteria use flagella to swim[1], but in many taxa, flagella are involved in causing infections[2]
The proteins that form the extra-cellular part of the bacterial flagellum polymerize by interaction of their N- and C-termini, which are disordered in solution[10,11]
The first segment of the helical bundle of domain D1, in the N-terminal region, is composed of α-helices α1 and α2, which consist of segments [Asp69-Arg99] and [Ile108-Asn124] that are connected by a short coil
Summary
Evolution of a nano-machine consisting of multiple parts, each with a specific function, is a complex process. The filament and the hook have distinct functions and their respective proteins, FliC and FlgE, have different three-dimensional structures. A special junction to assure a smooth connectivity is needed to link the hook and the filament, which have different structural and functional characteristics. This junction is composed of two ring-like structures made of multiple copies of FlgK and FlgL, respectively[9] (Fig. S1). We solved the three-dimensional structure of a major fragment of FlgK from C. jejuni, strain ATCC 700819/NCTC 11168, using X-ray crystallography Based on this structure, a model of the FlgK ring was made and fitted onto the model of the Campylobacter hook. There is a central domain, D1, which could be divided
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
