TY - JOUR

T1 - TapA acts as specific chaperone in TasA filament formation by strand complementation

AU - Roske, Yvette

AU - Lindemann, Florian

AU - Diehl, Anne

AU - Cremer, Nils

AU - Higman, Victoria A.

AU - Schlegel, Brigitte

AU - Leidert, Martina

AU - Driller, Kristina

AU - Turgay, Kürşad

AU - Schmieder, Peter

AU - Heinemann, Udo

AU - Oschkinat, Hartmut

N1 - We thank Regina Alver for initial cloning of TapA and TasA and construction of Bacillus strains. Further strains were provided by Ákos Kovács (Technical University of Denmark, Copenhagen). Thanks to Natalja Erdmann, Daniel Friedrich, and Matthias Herrera-Glomm (all Leibniz-Forschungsinstitut für Molekulare Pharmakologie, FMP) for excellent technical assistance, and to Ines Kretzschmar (FMP) for the synthesis of peptides. We acknowledge Daniel Roderer for initial electron microscopy investigations. We are grateful to Barth van Rossum for providing figures. H.O. acknowledges funding by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG), grant OS 106/17-1. K.T. was supported by the DFG (Tu106/6 & SPP1879) and the Max Planck Society. We acknowledge access to beamlines of the BESSY II storage ring via the Joint Berlin MX-Laboratory sponsored by the Helmholtz Zentrum Berlin für Materialien und Energie, the Freie Universität Berlin, the Humboldt-Universität zu Berlin, the Max-Delbrück-Centrum, the Leibniz-Institut für Molekulare Pharmakologie, and Charité–Universitätsmedizin Berlin.

PY - 2023/4/25

Y1 - 2023/4/25

N2 - Studying mechanisms of bacterial biofilm generation is of vital importance to understanding bacterial cell-cell communication, multicellular cohabitation principles, and the higher resilience of microorganisms in a biofilm against antibiotics. Biofilms of the nonpathogenic, gram-positive soil bacterium Bacillus subtilis serve as a model system with biotechnological potential toward plant protection. Its major extracellular matrix protein components are TasA and TapA. The nature of TasA filaments has been of debate, and several forms, amyloidic and non-Thioflavin T-stainable have been observed. Here, we present the three-dimensional structure of TapA and uncover the mechanism of TapA-supported growth of nonamyloidic TasA filaments. By analytical ultracentrifugation and NMR, we demonstrate TapA-dependent acceleration of filament formation from solutions of folded TasA. Solid-state NMR revealed intercalation of the N-terminal TasA peptide segment into subsequent protomers to form a filament composed of β-sandwich subunits. The secondary structure around the intercalated N-terminal strand β0 is conserved between filamentous TasA and the Fim and Pap proteins, which form bacterial type I pili, demonstrating such construction principles in a gram-positive organism. Analogous to the chaperones of the chaperone-usher pathway, the role of TapA is in donating its N terminus to serve for TasA folding into an Ig domain-similar filament structure by donor-strand complementation. According to NMR and since the V-set Ig fold of TapA is already complete, its participation within a filament beyond initiation is unlikely. Intriguingly, the most conserved residues in TasA-like proteins (camelysines) of Bacillaceae are located within the protomer interface.

AB - Studying mechanisms of bacterial biofilm generation is of vital importance to understanding bacterial cell-cell communication, multicellular cohabitation principles, and the higher resilience of microorganisms in a biofilm against antibiotics. Biofilms of the nonpathogenic, gram-positive soil bacterium Bacillus subtilis serve as a model system with biotechnological potential toward plant protection. Its major extracellular matrix protein components are TasA and TapA. The nature of TasA filaments has been of debate, and several forms, amyloidic and non-Thioflavin T-stainable have been observed. Here, we present the three-dimensional structure of TapA and uncover the mechanism of TapA-supported growth of nonamyloidic TasA filaments. By analytical ultracentrifugation and NMR, we demonstrate TapA-dependent acceleration of filament formation from solutions of folded TasA. Solid-state NMR revealed intercalation of the N-terminal TasA peptide segment into subsequent protomers to form a filament composed of β-sandwich subunits. The secondary structure around the intercalated N-terminal strand β0 is conserved between filamentous TasA and the Fim and Pap proteins, which form bacterial type I pili, demonstrating such construction principles in a gram-positive organism. Analogous to the chaperones of the chaperone-usher pathway, the role of TapA is in donating its N terminus to serve for TasA folding into an Ig domain-similar filament structure by donor-strand complementation. According to NMR and since the V-set Ig fold of TapA is already complete, its participation within a filament beyond initiation is unlikely. Intriguingly, the most conserved residues in TasA-like proteins (camelysines) of Bacillaceae are located within the protomer interface.

KW - Bacillus subtilis

KW - biofilm

KW - structure

KW - TapA/YqxM

KW - TasA

UR - http://www.scopus.com/inward/record.url?scp=85152670303&partnerID=8YFLogxK

U2 - 10.1073/pnas.2217070120

DO - 10.1073/pnas.2217070120

M3 - Article

C2 - 37068239

AN - SCOPUS:85152670303

VL - 120

SP - e2217070120

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 17

M1 - e2217070120

ER -