The binding of Tritrichomonas foetus to immobilized laminin-1 and its role in the cytotoxicity exerted by the parasite De ´ bora Barreiros Petro ´ polis, Juliany Cola Fernandes Rodrigues, Bruno da Rocha-Azevedo and Fernando Costa e Silva-Filho Correspondence Fernando Costa e Silva-Filho fcsf@biof.ufrj.br UFRJ – Instituto de Biofı ´sica Carlos Chagas Filho, CCS – Bloco G, Rio de Janeiro, Brazil Received 14 December 2007 Revised 8 February 2008 Accepted 7 April 2008 The recognition and binding of pathogens to extracellular matrix glycoproteins may determine the outcome of infective processes. The interaction between the bovine urogenital parasite Tritrichomonas foetus and the major basal membrane glycoprotein laminin-1 (LMN-1) was investigated. The chemical nature of parasite molecules involved in the attachment of T. foetus to immobilized LMN-1 and the influence of LMN-1 in the toxicity exerted by the parasite to HeLa cells was studied. Attachment of T. foetus to LMN-1 resulted in notable morphological alterations of the parasite, which became amoeboid. T. foetus recognized LMN-1 through specific amino acid sequences (AG73, C16, A208 and A13) in the LMN-1 molecule, and the protein nature of the parasite molecules involved in the recognition was demonstrated by dot-blot analyses. Such molecular recognition was cation-dependent and five LMN-1-binding molecules (220, 200, 130, 125 and 80 kDa) were identified in T. foetus. Binding of T. foetus to LMN-1 rendered the parasite toxic to HeLa cell monolayers. Thus, LMN-1 appears to provide signalling cues that mediate important cell functions in T. foetus concerning its interaction with host cells. INTRODUCTION Tritrichomonas foetus is a venereal pathogen of naturally bred cattle which may cause infertility and abortion (BonDurant, 2005). The related pathology, usually referred to as bovine trichomoniasis, includes different clinical manifestations between bulls and cows (BonDurant, 1997). In bulls the parasite can be detected at the preputial cavity to the urethra, and also in deeper parts of the urogenital tract (Parsonson et al., 1974). Once infected, bulls may harbour T. foetus throughout their lives without exhibiting clinical symptoms. In contrast, among cows the effects of the disease range from asymptomatic to severe clinical manifestations including vaginitis, cervicitis, endometritis and pyometra, resulting in transient infertility or fetal loss. Such clinical characteristics indicate the ability of T. foetus to invade host tissues (Parsonson et al., 1976; Lo ´ pez et al., 2000). Trichomonads possess a diversity of surface glycoconjugates including adhesins (Corbeil et al., 1989; Singh et al., 1999; Alderete & Garza, 1988) and extracellular matrix (ECM)-binding molecules (Silva-Filho et al., 1988), which play important roles during the interaction of the parasites with their hosts. In mammals, the ECM is composed of a complex assortment of glycoproteins and proteoglycans, which not only serve as scaffolds to provide a structural framework for tissues but also regulate cell behaviour (Bissell & Barcellos-Hoff, 1987; Nelson & Bissel, 2006). Among the ECM components, laminin-1 (LMN-1) is a large (#850 kDa) glycoprotein involved in various biological phenomena (Ekblom et al., 2003). LMN-1 provides signalling cues mediating important cell functions, including cell adhesion (Arrighi & Hurd, 2002; Ghosh et al., 1999; Gordon et al., 1993; Silva-Filho et al., 2002) and invasiveness by micro-organisms (Bandyopadhyay et al., 2001; Li et al., 1995). Biochemical studies focusing on the binding of eukaryotic cells to LMN-1 and the chemical nature of the related cell surface receptors have shown that the binding of some eukaryotic cells to LMN-1 is modulated by integrins (Mercurio, 1995; Hynes, 2002) and requires the participa- tion of certain cationic species. The functionality of integrins is indeed revealed only in the presence of minimum amounts of each one of Mn 2+ , Ca 2+ , Mg 2+ , or both Ca 2+ and Mg 2+ (Plow et al., 2000). In addition, it has been found that the oligosaccharide moieties of LMN-1 (Fujiwara et al., 1988) and their lectin-like counterpart molecules residing on pathogen surfaces (Ferreira et al., 2006; Saarela et al., 1996) may mediate both recognition and binding of micro-organisms to LMN-1. Since ECM binding by prokaryotic and eukaryotic patho- gens may trigger pathogenesis and tissue invasion (Li et al., Abbreviations: ECM, extracellular matrix; LMN-1. laminin-1. Microbiology (2008), 154, 2283–2290 DOI 10.1099/mic.0.2007/015941-0 2007/015941 G 2008 SGM Printed in Great Britain 2283