Abstract
BackgroundType IV pili are widely expressed among Gram-negative bacteria, where they are involved in biofilm formation, serve in the transfer of DNA, motility and in the bacterial attachment to various surfaces. Type IV pili in Shewanella oneidensis are also supposed to play an important role in extracellular electron transfer by the attachment to sediments containing electron acceptors and potentially forming conductive nanowires.ResultsThe potential nanowire type IV pilin PilBac1 from S. oneidensis was characterized by a combination of complementary structural methods and the atomic structure was determined at a resolution of 1.67 Å by X-ray crystallography. PilBac1 consists of one long N-terminal α-helix packed against four antiparallel β-strands, thus revealing the core fold of type IV pilins. In the crystal, PilBac1 forms a parallel dimer with a sodium ion bound to one of the monomers. Interestingly, our PilBac1 crystal structure reveals two unusual features compared to other type IVa pilins: an unusual position of the disulfide bridge and a straight α-helical section, which usually exhibits a pronounced kink. This straight helix leads to a distinct packing in a filament model of PilBac1 based on an EM model of a Neisseria pilus.ConclusionsIn this study we have described the first structure of a pilin from Shewanella oneidensis. The structure possesses features of the common type IV pilin core, but also exhibits significant variations in the α-helical part and the D-region.Electronic supplementary materialThe online version of this article (doi:10.1186/s12900-015-0031-7) contains supplementary material, which is available to authorized users.
Highlights
Type IV pili are widely expressed among Gram-negative bacteria, where they are involved in biofilm formation, serve in the transfer of DNA, motility and in the bacterial attachment to various surfaces
Sequence conservation and position in the genome The pilin protein encoded by the gene locus SO_0854 exhibits the conserved N-terminal leader sequence (MNTLQKG) and a hydrophobic patch of 22 residues expected to form a transmembrane helix, which is the hallmark of both type IV pilins and pseudopilins [45] (Figure 1A)
Bactofilins are fiber forming, membrane attached proteins that have been identified in many Gram-negative bacteria and they are associated with cytoskeleton related functions such as cell motility, cell morphology and cell division [54,55]
Summary
Type IV pili are widely expressed among Gram-negative bacteria, where they are involved in biofilm formation, serve in the transfer of DNA, motility and in the bacterial attachment to various surfaces. In the metal reducing bacteria Shewanella oneidensis and Geobacter sulfurreducens type IV pili have been implicated in extracellular electron transport (EET) pathways [7,8,9] Both of these organisms can respire on a variety of electron acceptors, including metals such as iron, manganese and uranium oxides, which has made these organisms attractive research targets in the fields of. Type IV pili have been associated with a more direct role in EET Both S. oneidensis and G. sulfurreducens can form conductive filaments that transfer electrons extracellularly over multiple cell lengths from one cell to another and from a cell to an electron acceptor [7,9]. The high overall similarity between G. sulfurreducens and S. oneidensis, including metabolic pathways, the prevalence of multiheme cytochromes and the formation of conductive filaments, makes it very likely that nanowires in both species are formed in a similar way and function based on the same principles
Sign-in/Register to view highlights & summary 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.
