Architecture and Evolution of Blade Assembly in β-propeller Lectins

Bonnardel, François; Kumar, Atal; Wimmerová, Michaela; Lahmann, Martina; Perez, Sergei; Varrot, A.; Lisacek, Frédérique; Imberty, Anne

doi:10.1016/j.str.2019.02.002

Cited by 31 publications

(32 citation statements)

References 66 publications

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“…SAXS and NS-EM derived models allowed a visual analysis of PmPV2, which reveal an antiparallel head-to-tail orientation of its protomers. In the NS-EM 3D reconstruction, the tachylectin subunit appears like a donut, which agreed with the predicted β-propeller structure (Bonnardel et al, 2019; Chen, Chan, & Wang, 2011; Fulop & Jones, 1999; Jawad & Paoli, 2002), whereas MACPF domain presents the characteristic flattened shape of the MACPF/CDC fold involved in oligomerization and pore formation (Rosado et al, 2007). Another interesting aspect of PmPV2 structure is the MACPF Ct domain.…”

Section: Discussionsupporting

confidence: 77%

Exaptation of two ancient immune proteins into a new dimeric pore-forming toxin in snails

Giglio

Ituarte

Milesi

et al. 2019

Preprint

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The Membrane Attack Complex-Perforin (MACPF) family is ubiquitously found in all kingdoms. They have diverse cellular roles but MACPF but pore-forming toxic function are very rare in animals. Here we present the structure of PmPV2, a MACPF toxin from the poisonous apple snail eggs, that can affect the digestive and nervous systems of potential predators. We report the three-dimensional structure of PmPV2, at 15 Å resolution determined by negative stain electron microscopy (NS-EM) and its solution structure by small angle X-ray scattering (SAXS). We found that PV2s differ from nearly all MACPFs in two respects: it is a dimer in solution and protomers combine two immune proteins into an AB toxin. MACPF chain is linked by a single disulfide bond to a tachylectin chain, and two heterodimers are arranged head-to-tail by non-covalent forces in the native protein. MACPF domain is fused with a putative new Ct-accessory domain exclusive to invertebrates. Tachylectin is a six-bladed β-propeller, similar to animal tectonins. We experimentally validated the predicted functions of both subunits and demonstrated for the first time that PV2s are true pore-forming toxins. The tachylectin ..B.. delivery subunit would bind to target membranes, and then its MACPF ..A.. toxic subunit disrupt lipid bilayers forming large pores altering the plasma membrane conductance. These results indicate that PV2s toxicity evolved by linking two immune proteins where their combined preexisting functions give rise to a new toxic entity with a novel role in defense against predation. This structure is an unparalleled example of protein exaptation.

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Section: Discussionsupporting

confidence: 77%

Exaptation of two ancient immune proteins into a new dimeric pore-forming toxin in snails

Giglio

Ituarte

Milesi

et al. 2019

Preprint

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“…We obtained a monodisperse peak corresponding to a protein of 72 ± 29.4 kDa corroborating that SapL1 forms dimers as FleA and other proteins of this family (monomer MW: 40 kDa, data not shown) [30]. The range of the standard deviation also suggested an ellipsoidal shape, which is characteristic for the dimers in this lectin family [45].…”

Section: Biochemical Characterizationsupporting

confidence: 75%

Biochemical and structural studies of target lectin SapL1 from the emerging opportunistic microfungusScedosporium apiospermum

Martínez-Alarcón

Pieters

Varrot

2020

Preprint

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Scedosporium apiospermum is an emerging opportunistic fungal pathogen responsible for life-threatening infections in immunocompromised patients. This fungus exhibits limited susceptibility to all current antifungals and, due its emerging character, its pathogenicity and virulence factors remain largely unknown. Carbohydrate binding proteins such as lectins are involved in host-pathogen interactions and may constitute valuable therapeutic targets to inhibit microbial adhesion to the host cells by using carbohydrate mimics. However, such lectins are still unidentified in S. apiospermum. Here, we present the first report of the identification and characterization of a lectin from S. apiospermum named SapL1. SapL1 is homologous to the conidial surface lectin FleA from Aspergillus fumigatus, known to be involved in the adhesion to host glycoconjugates present in human lung epithelium. The present report includes a detailed strategy to achieve SapL1 soluble expression in bacteria, its biochemical characterization, an analysis of its specificity and affinity by glycan arrays and isothermal titration calorimetry (ITC), as well as the structural characterization of its binding mode by X–ray crystallography. The information gathered here contributes to the understanding of glycosylated surface recognition by Scedosporium species and is essential for the design and development of antiadhesive glycodrugs targeting SapL1.Author summaryThe rate of infections caused by the airborne microfungus Scedosporium apiospermum has increased in the recent decades, especially in immunocompromised patients. It represents a therapeutic challenge due to its low susceptibility to all current antifungals, and the subsequent high mortality rate in disseminated scedosporiosis. Recently, the development of antiadhesive therapy has emerged as a novel strategy for the treatment and prevention of fungal infections. It aims to avoid the first step of infections, adhesion, by blocking the proteins responsible for attachment of the pathogens to the host-cells. Unfortunately, in the case of S. apiospermum, those proteins remain unknown but now we have identified a lectin (SapL1) encoded in its genome that is possibly involved in this process. In order to achieve a deep understanding of SapL1 specificity and interactions, we produced recombinant SapL1 in bacteria to carry out its biochemical and structural characterization. As predicted by our bioinformatics studies, SapL1 is a fucose binding lectin and we elucidated the interactions responsible for its binding specificity. Together, these informations should help to design efficient SapL1 inhibitors and therefore to generate potential antiadhesive drugs against this pathogen. Additionally, we have shown that SapL1 belongs to a highly conserved family of lectins that are present in other pathogens. Thus, the information presented here might also be useful for a broad spectrum drug development.

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“…Furthermore, co-crystal structures of Lb-Tec2 with methylated ligands revealed a highly conserved binding site architecture specifically designed for the recognition of methylated glycans. The identified conserved methylation recognition motif can now be used to identify lectins with this specificity and fold in other genomes using the PropLec server in the Unilectin database [10]. With regard to quaternary structure, the Lb-Tec2 crystal structure revealed a unique tetrameric organisation that was confirmed by small angle X-ray scattering (SAXS) measurements in solution [2].…”

Section: Introductionmentioning

confidence: 94%

Expression, Purification, and Functional Characterization of Tectonin 2 from Laccaria bicolor: A Six-Bladed Beta-Propeller Lectin Specific for O-Methylated Glycans

Wohlschlager

Titz

Künzler

et al. 2020

Methods in Molecular Biology

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Tectonins are conserved defense proteins of innate immune systems featuring a β-propeller fold. Tectonin 2 from Laccaria bicolor, Lb-Tec2, is the first fungal representative of the tectonin superfamily that has been described. In-depth characterization revealed a specificity for O-methylated glycans and identified a unique sequence motif and binding site architecture underlying this unusual specificity. This chapter provides information on how to produce and purify recombinant Lb-Tec2, characterize its interaction with O-methylated glycans and demonstrate its biological function.

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Architecture and Evolution of Blade Assembly in β-propeller Lectins

Cited by 31 publications

References 66 publications

Exaptation of two ancient immune proteins into a new dimeric pore-forming toxin in snails

Exaptation of two ancient immune proteins into a new dimeric pore-forming toxin in snails

Biochemical and structural studies of target lectin SapL1 from the emerging opportunistic microfungusScedosporium apiospermum

Expression, Purification, and Functional Characterization of Tectonin 2 from Laccaria bicolor: A Six-Bladed Beta-Propeller Lectin Specific for O-Methylated Glycans

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