Therefore, it can be implemented for precise epidemiological investigations of CD infections in animals
and humans. “
“Short-chain monodomain family comprises pairs of membrane proteins of about 200 amino acid residues each that belong to the chromate ion transporter (CHR) superfamily. The short-chain CHR homologous pair Chr3N/Chr3C from Bacillus Sirolimus research buy subtilis strain 168 confers chromate resistance only when both proteins are expressed. Membrane topology of the Chr3N and Chr3C proteins was determined in Escherichia coli by the analysis of translational fusions with reporter enzymes alkaline phosphatase and β-galactosidase. Each short-chain CHR protein was found to consist of five transmembrane segments with antiparallel orientation between them. The C terminus of Chr3N is located in the cytoplasm, whereas the C terminus of Chr3C is located in the periplasm. In silico analyses suggest that this antiparallel arrangement is shared by all protein members of the short-chain CHR3 subfamily and that the two Chr3N/Chr3C proteins might carry out distinct functions for the transport of chromate. The best-studied bacterial chromate resistance system is that of the Pseudomonas aeruginosa PD98059 ChrA protein, which functions as a chemiosmotic pump that extrudes chromate ions from the cytoplasm using the proton motive force (Alvarez et al., 1999). ChrA belongs to the chromate
ion transporter (CHR) superfamily (Nies et al., 1998; Nies, 2003), which includes hundreds of homologues from all three life domains (Díaz-Pérez et al., 2007; Henne et al., 2009). The CHR superfamily is composed ADP ribosylation factor of two families of sequences: (1) short-chain monodomain family made up of proteins of about 200 amino acid (aa) residues and (2) long-chain bidomain family of about 400 aa (Díaz-Pérez et al., 2007). Genes encoding short-chain CHR proteins are organized mainly as homologous tandem pairs (Díaz-Pérez et al., 2007). Several proteins of the long-chain CHR family have been demonstrated to function as membrane
transporters able to extrude chromate ions from the cytoplasm (reviewed in Ramírez-Díaz et al., 2008), and paired genes encoding short-chain CHR proteins from Bacillus subtilis strain 168 were also shown to confer resistance to chromate by chromate efflux when expressed in Escherichia coli (Díaz-Magaña et al., 2009). With respect to membrane topology, the long-chain ChrA protein from Cupriavidus metallidurans has been reported to have 10 transmembrane segments (TMSs), in an unusual 4 + 6 arrangement (Nies et al., 1998). Another long-chain CHR member, the ChrA protein from P. aeruginosa, possesses 13 TMSs in an unusual 6 + 1 + 6 arrangement, with one extra TMS inserted in the middle of the two homologous domains (Jiménez-Mejía et al., 2006). This last arrangement in P.