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          Institute: MPI für Biophysik     Collection: Abt. Strukturbiologie     Display Documents

ID: 585118.0, MPI für Biophysik / Abt. Strukturbiologie
Unusual N-terminal ααβαββα Fold of PilQ from Thermus thermophilus Mediates Ring Formation and Is Essential for Piliation
Authors:Burkhardt, Janin; Vonck, Janet; Langer, Julian D.; Salzer, Ralf; Averhoff, Beate
Date of Publication (YYYY-MM-DD):2012
Title of Journal:The Journal of Biological Chemistry
Journal Abbrev.:J. Biol. Chem.
Issue / Number:11
Start Page:8484
End Page:8494
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:DNA translocators of natural transformation systems are complex systems critical for the uptake of free DNA and provide a powerful mechanism for adaptation to changing environmental conditions. In natural transformation machineries, outer membrane secretins are suggested to form a multimeric pore for the uptake of external DNA. Recently, we reported on a novel structure of the DNA translocator secretin complex, PilQ, in Thermus thermophilus HB27 comprising a stable cone and cup structure and six ring structures with a large central channel. Here, we report on structural and functional analyses of a set of N-terminal PilQ deletion derivatives in T. thermophilus HB27. We identified 136 N-terminal residues exhibiting an unusual ααβαββα fold as a ring-building domain. Deletion of this domain had a dramatic effect on twitching motility, adhesion, and piliation but did not abolish natural transformation. These findings provide clear evidence that the pilus structures of T. thermophilus are not essential for natural transformation. The truncated complex was not affected in inner and outer membrane association, indicating that the 136 N-terminal residues are not essential for membrane targeting. Analyses of complex formation of the truncated PilQ monomers revealed that the region downstream of residue 136 is required for multimerization, and the region downstream of residue 207 is essential for monomer stability. Possible implications of our findings for the mechanism of DNA uptake are discussed.
Free Keywords:DNA Transformation; Membrane Proteins; Membrane Transport; Protein Assembly; Protein Complexes; Secretins; Thermophile; Type IV Pili
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Biophysik/Abteilung Strukturbiologie
MPI für Biophysik/Abteilung Molekulare Membranbiologie
External Affiliations:Molecular Microbiology and Bioenergetics, Inst. of Molecular Biosciences, Goethe University, Frank- furt/Main, Max-von-Laue-Strasse 9, D-60438 Frankfurt, Germany
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