The wild type and CHR161 (mntR) strains were also included in the assay for comparative purposes. Strains were grown in M63 medium with glucose, ectoine or hydroxyectoine as the sole carbon sources, at salinities ranging from 0.6 to 2.5 M NaCl. No significant differences

were found between the growth of the mntR mutant and the wild type strain with any carbon source at any salinity tested (Figure 7 and Table 2). In contrast, mutant CHR183 (Csal0866) reproduced the phenotype of strain CHR95 and was able to use ectoine and, to a lower extent, hydroxyectoine as the sole carbon and energy sources at low salinity (Figure 7 and Table 2). Like strain CHR95, and if compared to the wild type, growth of CHR183 (Csal0866) with glucose was delayed from 0.6 Vistusertib concentration to 1.5 M NaCl, and severely impaired at 2.5 M NaCl (data not shown). The above findings suggest that deletion of gene Csal0866 enables the strain to use ectoines as carbon source at low salinity, as

a consequence of ectoine transport deregulation at this salinity. Therefore, the product of Csal0866 was named EupR (after Ectoine uptake Regulator). Figure 7 C. salexigens EupR is involved in the control of ectoine uptake. Wild type strain (squares), CHR161 mutant (mntR::Ω) (triangles) and CHR183 mutant (eupR::Ωaac) (circles) were grown at 37°C in M63 medium with 20 mM ectoine (black markers) or 20 mM hydroxyectoine (white markers) and 0.6 (A), 0.75 (B) or 1.5 (C) M NaCl. Values shown are the mean of two replicas of each condition in three independent experiment ± SD (standard deviation) Table this website 2 Growth rates of C. salexigens strains CHR161 (mntR) and CHR183 (eupR) on ectoines at different salinities Strain and carbon source Growth rate (h-1) CHR161 ectoine    0.6 M 0    0.75 M 0.011    1.5 M 0.041    2.5 M 0.029 CHR161 hydroxyectoine Sitaxentan    0.6 M 0    0.75 M 0.012    1.5 M 0.024    2.5 M 0 CHR183 ectoine    0.6 M 0.033    0.75 M 0.044    1.5 M 0.040    2.5 M 0.016 CHR183 hydroxyectoine

   0.6 M 0.015    0.75 M 0.021    1.5 M 0.023    2.5 M 0 EupR is a response regulator of the NarL/FixJ family of proteins To further characterize EupR, we analyzed in detail its domain composition and its phylogenetic relationship with other proteins showing the same DNA-binding domain. First, both NCBI/CDD and UniProt entries for this protein included an N-terminal signal receiver domain (REC) and a LuxR_C-like DNA-binding helix-turn-helix (HTH) domain. All first 50 hits of the list retrieved after iterative PSI-BLAST, inspected with the CDD domain viewer [27], also showed the same domain composition. Second, we searched Selleck PRN1371 Csal866 annotation in the specialized Signaling Census database (see Methods), which includes total counts of signal transduction proteins in completely sequenced genomes [28, 29]. In this database, Csal866 was included as a response regulator of the NarL family.