Invasion of insect cells bySpiroplasma citriinvolves spiralin relocalization and lectin/glycoconjugate-type interactions

Abstract

SummarySpiroplamas are helical, cell wall-less bacteria belonging to the Class Mollicutes, a group of microorganisms phylogenetically related to low G+C, Gram-positive bacteria. Spiroplasma species are all found associated with arthropods and a few, including Spiroplasma citri are pathogenic to plant. Thus S. citri has the ability to colonize cells of two very distinct hosts, the plant and the insect vector. While spiroplasmal factors involved in transmission by the leafhopper Circulifer haematoceps have been identified, their specific contribution to invasion of insect cells is poorly understood. In this study we provide evidence that the lipoprotein spiralin plays a major role in the very early step of cell invasion. Confocal laser scanning immunomicroscopy revealed a relocalization of spiralin at the contact zone of adhering spiroplasmas. The implication of a role for spiralin in adhesion to insect cells was further supported by adhesion assays showing that a spiralin-less mutant was impaired in adhesion and that recombinant spiralin triggered adhesion of latex beads. We also showed that cytochalasin D induced changes in the surface-exposed glycoconjugates, as inferred from the lectin binding patterns, and specifically improved adhesion of S. citri wild-type but not of the spiralin-less mutant. These results indicate that cytochalasin D exposes insect cell receptors of spiralin that are masked in untreated cells. In addition, competitive adhesion assays with lectins strongly suggest spiralin to exhibit glycoconjugate binding properties similar to that of the Vicia villosa agglutinin (VVA) lectin.

Identification of proteome, antigen protein and antigen membrane protein fromSpiroplasma eriocheiris

“…The most abundant membrane protein of S. citri , spiralin, has been verified to play a major role in the very early step of cell invasion (Duret et al . ). Phosphoglycerate kinase is a cytosolic protein on surface and research has shown that S. citri transmission by its insect vector is correlated with its ability to bind actin (Labroussaa et al .…”

SPE0313 located at cell membrane of Spiroplasma eriocheiris is required for adhesion and invasion Eriocheir sinensis hemocytes

“…Phytoplasma mali” (Boonrod, Munteanu, Jarausch, Jarausch, & Krczal, ). And spiralin which is the richest membrane protein of Spiroplasma citri also takes a major role in the early phase of cell invasion (Duret et al, ). The surface protein P86 of S. citri has adhesive function when it infects with its host Circulifer tenellus (Yu, Wayadande, & Fletcher, ; glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), pyruvate kinase and enolase are not only antigenic and membrane proteins, but also involved in adherence in Mycooplasma gallisepticum (Alvare, Blaylock, & Baseman, ; Chen et al, ; He et al, ).…”

Interactions of maize bushy stunt phytoplasma with the leafhopper vector, <i>Dalbulus maidis</i> (Delong and Wolcott) (Hemiptera: Cicadellidae) and associated microbiota

“…Keywords: Biofilm; Endosymbionts; MBSP movement; Ultrastructure; Microvilli Phytoplasmas are obligated phytopathogenic bacteria living in both plants and insects depending on them for its acquisition and inoculation DURET et al, 2014). They are acquired by its vector passively during feeding on infected plants with consumption times being as short as few minutes but generally measured in hours (WEINTRAUB, 2007).…”

“…During this process, internalization of spiroplasmas into insect cells is an obligate step which requires intimate interactions, for both crossing the gut epithelium (acquisition) and invading the salivary gland cells (transmission) (DURET et al, 2014).…”

“…In the interaction of Spiroplasma citri and its vector Circulifer haematoceps (Mulsant & Rey, 1855) (Hemiptera: Cicadellidae) the spiroplasma ability to undergo morphological changes from helical, in the phloem sap and insect hemolymph, to rounded shape when internalized into insect cells has been demonstrated (KWON;WAYADANDE;FLETCHER, 1999;OZBEK et al, 2003), with robust interactions between spiroplasmal and host cell membrane proteins mediated by phosphoglycerate kinase (PGK), the adhesin ScARP3d, and the lipoprotein spiralin serving for attaching to the insect cells (DURET et al, 2014).…”