Photorhabdus laumondii is a well-known bacterium with a complex life cycle involving mutualism with nematodes of the genus Heterorhabditis and pathogenicity towards insect hosts. It provides an excellent model for studying the diverse roles of lectins, saccharide-binding proteins, in both symbiosis and pathogenicity. This study focuses on the seven-bladed β-propeller lectins of P. laumondii (PLLs), examining their biochemical properties (structure and saccharide specificity) and biological functions (gene expression, interactions with the nematode symbiont, and the host immune system response). Structural analyses revealed diverse oligomeric states among PLLs and a unique organisation of binding sites not described outside the PLL lectin family. Lectins exhibited high specificity for fucosylated and O-methylated saccharides with a significant avidity effect for multivalent ligands. Gene expression analysis across bacterial growth phases revealed that PLLs are predominantly expressed during the exponential phase. Interaction studies with the host immune system demonstrated that PLL5 uniquely induced melanisation in Galleria mellonella hemolymph. Furthermore, PLL2, PLL3, and PLL5 interfered with reactive oxygen species production in human blood cells, indicating their potential role in modulating host immune responses. Biofilm formation assays and binding studies with nematode life stages showed no significant involvement of PLLs in nematode colonization. Our findings highlight the primary role of PLLs in Photorhabdus pathogenicity rather than in symbiosis and offer valuable insight into the fascinating dynamics within the Photorhabdus-nematode-insect triparted system.

Central European Institute of Technology Masaryk University Kamenice 5 Brno 625 00 Czech Republic

Department of Biochemistry Faculty of Science Masaryk University Kotlářská 267 2 Brno 611 37 Czech Republic

Department of Experimental Biology Faculty of Science Masaryk University Kotlářská 267 2 Brno 611 37 Czech Republic

National Centre for Biomolecular Research Faculty of Science Masaryk University Kotlářská 267 2 Brno 611 37 Czech Republic

See more in PubMed

Altschul  SF, Gish  W, Miller  W, Myers  EW, Lipman  DJ. 1990. Basic local alignment search tool. J Mol Biol. 215:403–410. 10.1016/S0022-2836(05)80360-2. PubMed DOI

Bedding  RA, Molyneux  AS. 1982. Penetration of insect cuticle by infective juveniles of DOI

Beshr  G  et al.  2017. PubMed DOI PMC

Blanchard  B, Imberty  A, Varrot  A. 2014. Secondary sugar binding site identified for LecA lectin from PubMed DOI

Brautigam  CA. 2015. Calculations and publication-quality illustrations for analytical ultracentrifugation data. Meth Enzymol. 562:109–133. 10.1016/bs.mie.2015.05.001. PubMed DOI

Brown  GD, Willment  JA, Whitehead  L. 2018. C-type lectins in immunity and homeostasis. Nat Rev Immunol. 18:374–389. 10.1038/s41577-018-0004-8. PubMed DOI

Cerenius  L, Söderhäll  K. 2004. The prophenoloxidase-activating system in invertebrates. Immunol Rev. 198:116–126. 10.1111/j.0105-2896.2004.00116.x. PubMed DOI

Ciche  TA, Ensign  JC. 2003. For the insect pathogen PubMed DOI PMC

Ciche  TA, Kim  K-S, Kaufmann-Daszczuk  B, Nguyen  KCQ, Hall  DH. 2008. Cell invasion and matricide during PubMed DOI PMC

Ciche  TA, Bintrim  SB, Horswill  AR, Ensign  JC. 2001. A Phosphopantetheinyl transferase homolog is essential for PubMed DOI PMC

Cimen  H, Touray  M, Gulsen  SH, Hazir  S. 2022. Natural products from PubMed DOI

Cioci  G  et al.  2006. Β-propeller crystal structure of PubMed DOI

Clarke  DJ. 2008. PubMed DOI

Clarke  DJ. 2014. The genetic basis of the symbiosis between PubMed DOI

Clarke  DJ. 2020. PubMed DOI

Daborn  PJ, Waterfield  N, Blight  MA, Ffrench-Constant  RH. 2001. Measuring virulence factor expression by the pathogenic bacterium PubMed DOI PMC

Dominelli  N, Platz  F, Heermann  R. 2022. The insect pathogen PubMed DOI PMC

Duchaud  E  et al.  2003. The genome sequence of the entomopathogenic bacterium PubMed DOI

Emsley  P, Lohkamp  B, Scott  WG, Cowtan  K. 2010. Features and development of Coot. Acta Crystallogr D Biol Crystallogr. 66:486–501. 10.1107/S0907444910007493. PubMed DOI PMC

Faltinek  L  et al.  2019. Lectin PLL3, a novel monomeric member of the seven-bladed β-propeller lectin family. Molecules. 24:4540. 10.3390/molecules24244540. PubMed DOI PMC

Ffrench-Constant  R  et al.  2003. PubMed DOI

Forst  S, Dowds  B, Boemare  N, Stackebrandt  E. 1997. PubMed DOI

Fujdiarová  E  et al.  2021. Heptabladed β-propeller lectins PLL2 and PHL from PubMed DOI

Hapeshi  A, Benarroch  JM, Clarke  DJ, Waterfield  NR. 2019. Iso-propyl stilbene: a life cycle signal?  Microbiology. 165:516–526. 10.1099/mic.0.000790. PubMed DOI

Haydak  MH. 1936. A food for rearing laboratory animals. J Econ Entomol. 29:1026.

Held  KG, LaRock  CN, D’Argenio  DA, Berg  CA, Collins  CM. 2007. A metalloprotease secreted by the insect pathogen PubMed DOI PMC

Hokke  CH, Deelder  AM, Hoffmann  KF, Wuhrer  M. 2007. Glycomics-driven discoveries in PubMed DOI

Hunter  SW, Fujiwara  T, Brennan  PJ. 1982. Structure and antigenicity of the major specific glycolipid antigen of PubMed DOI

Imai  Y  et al.  2019. A new antibiotic selectively kills gram-negative pathogens. Nature. 576:459–464. 10.1038/s41586-019-1791-1. PubMed DOI PMC

Jančaříková  G  et al.  2017. Characterization of novel bangle lectin from PubMed DOI PMC

Jankowska  E  et al.  2018. A comprehensive PubMed DOI PMC

Jiménez-Castells  C  et al.  2017. Gender and developmental specific N-glycomes of the porcine parasite PubMed DOI PMC

Kabsch  W. 2010. XDS. Acta Crystallogr D Biol Crystallogr. 66:125–132. 10.1107/S0907444909047337. PubMed DOI PMC

Kostlánová  N  et al.  2005. The fucose-binding lectin from PubMed DOI

Krug  M, Weiss  MS, Heinemann  U, Mueller  U. 2012. XDSAPP: a graphical user interface for the convenient processing of diffraction data using XDS. J Appl Crystallogr. 45:568–572. 10.1107/S0021889812011715. DOI

Kumar  S  et al.  2003. The role of reactive oxygen species on plasmodium melanotic encapsulation in PubMed DOI PMC

Kumar  A  et al.  2016. A novel Fucose-binding lectin from PubMed DOI PMC

Lacey  LA  et al.  2015. Insect pathogens as biological control agents: back to the future. J Invertebr Pathol. 132:1–41. 10.1016/j.jip.2015.07.009. PubMed DOI

Lee  RT, Lee  YC. 2000. Affinity enhancement by multivalent lectin-carbohydrate interaction. Glycoconj J. 17:543–551. 10.1023/A:1011070425430. PubMed DOI

Li  Y  et al.  2014. PubMed DOI

Lis  H, Sharon  N. 1998. Lectins: carbohydrate-specific proteins that mediate cellular recognition. Chem Rev. 98:637–674. 10.1021/cr940413g. PubMed DOI

Mersha  FB, McClung  CM, Chen  M, Ruse  CI, Foster  JM. 2023. Defining the filarial N-glycoproteome by glycosite mapping in the human parasitic nematode PubMed DOI PMC

Murshudov  GN  et al.  2011. REFMAC 5 for the refinement of macromolecular crystal structures. Acta Crystallogr D Biol Crystallogr. 67:355–367. 10.1107/S0907444911001314. PubMed DOI PMC

Nakamura-Tsuruta  S, Kominami  J, Kuno  A, Hirabayashi  J. 2006. Evidence that PubMed DOI

Regaiolo  A, Dominelli  N, Andresen  K, Heermann  R. 2020. The biocontrol agent and insect pathogen PubMed DOI PMC

Schuck  P. 2000. Size-distribution analysis of macromolecules by sedimentation velocity ultracentrifugation and lamm equation modeling. Biophys J. 78:1606–1619. 10.1016/S0006-3495(00)76713-0. PubMed DOI PMC

Sharon  N. 1987. Bacterial lectins, cell-cell recognition and infectious disease. FEBS Lett. 217:145–157. 10.1016/0014-5793(87)80654-3. PubMed DOI

Sharon  N. 2007. Lectins: carbohydrate-specific reagents and biological recognition molecules. J Biol Chem. 282:2753–2764. 10.1074/jbc.X600004200. PubMed DOI

Sheikh  MO  et al.  2019. Correlations between LC-MS/MS-detected Glycomics and NMR-detected metabolomics in Caenorhabditis elegans development. Front Mol Biosci. 6:49. 10.3389/fmolb.2019.00049. PubMed DOI PMC

Sievers  F  et al.  2014. Fast, scalable generation of high-quality protein multiple sequence alignments using Clustal omega. Mol Syst Biol. 7:539–539. 10.1038/msb.2011.75. PubMed DOI PMC

Sommer  R  et al.  2018. Crystal structures of fungal Tectonin in complex with O-methylated Glycans suggest key role in innate immune Defense. Structure. 26:391–402.e4. 10.1016/j.str.2018.01.003. PubMed DOI

Somvanshi  VS, Kaufmann-Daszczuk  B, Kim  K, Mallon  S, Ciche  TA. 2010. PubMed DOI

Staudacher  E. 2012. Methylation – an uncommon modification of glycans. Biol Chem. 393:675–685. 10.1515/hsz-2012-0132. PubMed DOI PMC

Šulák  O  et al.  2011. PubMed DOI PMC

Turlin  E  et al.  2006. Proteome analysis of the phenotypic variation process in PubMed DOI

Walski  T, De Schutter  K, Van Damme  EJM, Smagghe  G. 2017. Diversity and functions of protein glycosylation in insects. Insect Biochem Mol Biol. 83:21–34. 10.1016/j.ibmb.2017.02.005. PubMed DOI

Waterfield  NR, Ciche  T, Clarke  D. 2009. PubMed DOI

Wharton  DA, Jenkins  T. 1978. Structure and chemistry of the egg-Shell of a nematode ( PubMed DOI

Wimmerova  M, Mitchell  E, Sanchez  J-F, Gautier  C, Imberty  A. 2003. Crystal structure of fungal lectin: six-bladed beta-propeller fold and novel fucose recognition mode for PubMed DOI

Winn  MD  et al.  2011. Overview of the CCP 4 suite and current developments. Acta Crystallogr D Biol Crystallogr. 67:235–242. 10.1107/S0907444910045749. PubMed DOI PMC

Wiseman  T, Williston  S, Brandts  JF, Lin  LN. 1989. Rapid measurement of binding constants and heats of binding using a new titration calorimeter. Anal Biochem. 179:131–137. 10.1016/0003-2697(89)90213-3. PubMed DOI

Wohlschlager  T  et al.  2014. Methylated glycans as conserved targets of animal and fungal innate defense. Proc Natl Acad Sci USA. 111:E2787–E2796. 10.1073/pnas.1401176111. PubMed DOI PMC

Zamora-Lagos  M-A  et al.  2018. Phenotypic and genomic comparison of PubMed DOI PMC

Zhang  J, Chatterjee  D, Brennan  PJ, Spencer  JS, Liav  A. 2010. A modified synthesis and serological evaluation of neoglycoproteins containing the natural disaccharide of PGL-I from PubMed DOI PMC