Structural interactions define assembly adapter function of a type II secretion system pseudopilin

Escobar, Cristian A.; Douzi, Badreddine; Ball, Geneviève; Barbat, Brice; Alphonse, Sébastien; Quinton, Loïc; Voulhoux, Romé; Forest, Katrina T.

doi:10.1016/j.str.2021.05.015

Cited by 22 publications

(52 citation statements)

References 64 publications

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“…They can be incorporated into pili at different locations and can have profound effects on pilus assembly and function. Strikingly, many Gram-negative bacteria expressing T4P or T2SSs possess a set of core minor pilins that are central components of the assembly machinery ( Giltner et al., 2012 ; Escobar et al., 2021 ). In some systems additional accessory minor pilins that can be dispensable for pilus biogenesis can be involved in specific pilus associated functions such as adhesion to host cells, bacterial aggregation, and DNA uptake ( Helaine et al., 2005 ; Helaine et al., 2007 ; Brissac et al., 2012 ; Cehovin et al., 2013 ; Imhaus and Dumenil, 2014 ; Ng et al., 2016 ).…”

Section: Introductionmentioning

confidence: 99%

The Role of Minor Pilins in Assembly and Function of the Competence Pilus of Streptococcus pneumoniae

Oliveira

Aschtgen

Erp

et al. 2021

Front. Cell. Infect. Microbiol.

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The remarkable genomic plasticity of Streptococcus pneumoniae largely depends on its ability to undergo natural genetic transformation. To take up extracellular DNA, S. pneumoniae assembles competence pili composed of the major pilin ComGC. In addition to ComGC, four minor pilins ComGD, E, F, and G are expressed during bacterial competence, but their role in pilus biogenesis and transformation is unknown. Here, using a combination of protein-protein interaction assays we show that all four proteins can directly interact with each other. Pneumococcal ComGG stabilizes the minor pilin ComGD and ComGF and can interact with and stabilize the major pilin ComGC, thus, deletion of ComGG abolishes competence pilus assembly. We further demonstrate that minor pilins are present in sheared pili fractions and find ComGF to be incorporated along the competence pilus by immunofluorescence and electron microscopy. Finally, mutants of the invariant Glu5 residue (E5), ComGDE5A or ComGEE5A, but not ComGFE5A, were severely impaired in pilus formation and function. Together, our results suggest that ComGG, lacking E5, is essential for competence pilus assembly and function, and plays a central role in connecting the pneumococcal minor pilins to ComGC.

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Section: Introductionmentioning

confidence: 99%

The Role of Minor Pilins in Assembly and Function of the Competence Pilus of Streptococcus pneumoniae

Oliveira

Aschtgen

Erp

et al. 2021

Front. Cell. Infect. Microbiol.

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“…Their role and mechanism of action are likely to be the same since HIJK sets from different T4F are functionally interchangeable in promoting filament assembly 24 . These pilins interact to form a quasihelical complex 25,26 , with symmetry parameters consistent with T4F. This complex is capped by the bulky K subunit, suggesting a localisation at the pilus tip 25,26 , which was recently confirmed by cryo-electron tomography 27 (cryo-ET) in Myxococcus xanthus T4P.…”

Section: Introductionmentioning

confidence: 59%

“…PilABC pilins are also encoded by an operon, and PilA lacks the Glu 5 residue 35 . Structural studies showed that HIJK pilins interact to form a quasihelical complex 25,26 in the order KIJH, from top to bottom. The complex – capped by the modular K subunit – was thus proposed to be at the tip of T4F because no additional subunits could fit above the bulky K without significant steric hindrance 25 , which was recently confirmed by cryo-ET 27 .…”

Section: Discussionmentioning

confidence: 99%

“…Critically, both HIJK 21–23 and PilABC 34 pilins are essential for filament assembly, which is compatible with PilA being a nucleator initiating filament assembly, a role attributed to the I subunit in the HIJK complex 28,29 . For the HIJK complex, it was proposed that (1) I interacts with J in the membrane to form a staggered complex, (2) the IJ complex interacts with K via its I subunit, initiating filament assembly by forming a quasihelical complex 25 , (3) the IJK complex interacts with H via its J subunit 26 , and (4) the HIJK complex interacts with the major pilin via its H subunit 26 . The series of events is similar for PilABC, albeit simpler.…”

Section: Discussionmentioning

confidence: 99%

“…These pilins interact to form a quasihelical complex 25,26 , with symmetry parameters consistent with T4F. This complex is capped by the bulky K subunit, suggesting a localisation at the pilus tip 25,26 , which was recently confirmed by cryoelectron tomography 27 (cryo-ET) in Myxococcus xanthus T4P. Since T4F are assembled from tip to base 3 , the HIJK complex is therefore thought to initiate filament assembly 28,29 .Recently, the study of T4F in monoderm bacteria opened new research avenues 30 , with Streptococcus sanguinis becoming a cutting edge model 31 .…”

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confidence: 99%

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Full structure/function analysis of all the pilin subunits in a type 4 pilus: a complex of minor pilins in Streptococcus sanguinis mediates binding to glycans

Shahin

Sheppard

Raynaud

et al. 2022

Preprint

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Type 4 filaments (T4F)- of which type 4 pili (T4P) are the archetype - are a superfamily of filamentous nanomachines nearly ubiquitous in prokaryotes. T4F are polymers of one major pilin that also contain minor pilins whose roles are often poorly understood. Here, we complete the structure/function analysis of the full set of T4P pilins in the opportunistic pathogen Streptococcus sanguinis. We determined the structure of the minor pilin PilA, which is unexpectedly similar to one of the subunits of a tip-located complex of four minor pilins, widely conserved in T4F. We found that PilA interacts and dramatically stabilises the minor pilin PilC. We determined the structure of PilC, showing that it is a modular pilin with a lectin module binding a specific subset of glycans prevalent in the human glycome, the host of S. sanguinis. Altogether, our findings support a model whereby the minor pilins in S. sanguinis T4P form a tip-located complex promoting adhesion to various host receptors. Our findings have general implications for a group of minor pilins widely conserved in T4F.

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Refining the Dynamic Network of T2SS Endopilus Tip Heterocomplex Combining cw‐EPR and Nitroxide–Gd^III Distance Measurements

et al. 2023

Self Cite

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The type 2 secretion system (T2SS) is a bacterial nanomachine composed of an inner membrane assembly platform, an outer membrane pore and a dynamic endopilus. T2SS endopili are organized into a homo-multimeric body formed by the major pilin capped by a heterocomplex of four minor pilins. The first model of the T2SS endopilus was recently released, even if structural dynamics insights are still required to decipher the role of each protein in the full tetrameric complex. Here, we applied continuous-wave and pulse EPR spectroscopy using nitroxide-gadolinium orthogonal labelling strategies to investigate the hetero-oligomeric assembly of the minor pilins. Overall, our data are in line with the endopilus model even if they evidenced conformational flexibility and alternative orientations at local scale of specific regions of minor pilins. The integration of different labelling strategies and EPR experiments demonstrates the pertinence of this approach to investigate protein-protein interactions in such multiprotein heterocomplexes.

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Structural interactions define assembly adapter function of a type II secretion system pseudopilin

Cited by 22 publications

References 64 publications

The Role of Minor Pilins in Assembly and Function of the Competence Pilus of Streptococcus pneumoniae

The Role of Minor Pilins in Assembly and Function of the Competence Pilus of Streptococcus pneumoniae

Full structure/function analysis of all the pilin subunits in a type 4 pilus: a complex of minor pilins in Streptococcus sanguinis mediates binding to glycans

Refining the Dynamic Network of T2SS Endopilus Tip Heterocomplex Combining cw‐EPR and Nitroxide–Gd^III Distance Measurements

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Structural interactions define assembly adapter function of a type II secretion system pseudopilin

Cited by 22 publications

References 64 publications

The Role of Minor Pilins in Assembly and Function of the Competence Pilus of Streptococcus pneumoniae

The Role of Minor Pilins in Assembly and Function of the Competence Pilus of Streptococcus pneumoniae

Full structure/function analysis of all the pilin subunits in a type 4 pilus: a complex of minor pilins in Streptococcus sanguinis mediates binding to glycans

Refining the Dynamic Network of T2SS Endopilus Tip Heterocomplex Combining cw‐EPR and Nitroxide–GdIII Distance Measurements

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Refining the Dynamic Network of T2SS Endopilus Tip Heterocomplex Combining cw‐EPR and Nitroxide–Gd^III Distance Measurements