burnetii BKM120 strain

(RSA493) Nine Mile phase I genomic sequence, which revealed a set of genes with significant homology to the Dot/Icm type IVB secretion system (T4BSS) of Legionella pneumophila. In L. pneumophila, the T4BSS system consists of 26 ORFs, of which 23 share significant homology with C. burnetii ORFs (Seshadri et al., 2003). Studies show that the L. pneumophila T4BSS is required for intracellular survival, effector protein secretion, and replication within host cells (Marra et al., 1992; Berger & Isberg, 1993; Vogel et al., 1998; Bruggemann et al., 2006; Ninio & Roy, 2007; Kubori et al., 2008; Shin & Roy, 2008), thus playing a vital role in the infectious process of L. pneumophila. Moreover, the genome sequence revealed C. burnetii ORFs containing eukaryotic Ankyrin-binding repeat domains (Pan et al., 2008; Voth et al., 2009). Subsequently, these ORFs were shown to be secreted by L. pneumophila in a T4BSS-dependent manner (Pan et al., 2008; Voth et al., 2009), further implicating

the C. burnetii T4BSS as a significant contributor to cellular pathogenesis, Inhibitor Library datasheet and yet characterization of the T4BSS structure in C. burnetii is lacking. In general, T4SS serve to export virulence factors, which include nucleoprotein complexes and effector proteins, into a host or into the extracellular milieu (Christie & Vogel, 2000; Sexton & Vogel, 2002; Cascales & Christie, 2003). T4SS have been subdivided into two families: (1) the VirB/D4 (T4ASS) and (2) the Dot/Icm (T4BSS) systems (Christie & Vogel, 2000).

The T4ASS of Agrobacterium tumefaciens directly injects effector molecules into adjacent cells (Christie Pyruvate dehydrogenase & Vogel, 2000) as well as into the extracellular environment (Dillard & Seifert, 2001; Hofreuter et al., 2001). Interestingly, VirB8, part of the core complex, was reported to localize at the pole of A. tumefaciens cells (Kumar et al., 2000), and the bacterium attaches to host plant cells perpendicular to the bacterial poles (Matthysse, 1987). In L. pneumophila, the T4BSS is essential for cellular pathogenesis via secretion of effector proteins into a host cell (Sexton & Vogel, 2002; Christie et al., 2005). In L. pneumophila, the T4BSS component, DotF, appears to demonstrate polar localization (Jeong et al., 2006). Virulence factors localize or are dispersed about the pole(s) of a wide range of bacteria, and include alternate secretion systems, effector protein molecules, and surface membrane-associated proteins. Evidence suggests that the T3SS of Shigella flexneri is present at the poles of the bacteria before the secretion of IpaC (Jaumouille et al., 2008). Recently, the Mycobacterium marinum Esx-1 T7SS was shown to secrete Mh3864 at the poles and that a core Esx-1 component, Mh3870, localized preferentially to the poles (Carlsson et al., 2009).