, 2009). For Cry3A protein (the most important coleopteran-specific Cry toxin), loop 1 has an important function in biological activity: the mutations AZD4547 R345A, Y350F, Y351F, ΔY350 and ΔY351 showed higher levels of toxicity against Tenebrio molitor (Coleoptera) (Pardo-López et al., 2009). SN1917 has several changes related to these observations, with respect to the parental Cry1Ba (R345Q, Y349M and ΔY350). It may be that these residues are important factors of activity, for example arginine has a positive

charge because the guanido group is ionized over the entire pH range in which proteins exist naturally, and the hydroxyl group of the phenolic ring of tyrosine residues makes this aromatic ring relatively reactive in electrophilic substitution reactions (Creighton, 1993). On the other hand, anticoleopteran Cry proteins are only toxic after in vitro solubilization, probably because the protoxin cannot be solubilized at the neutral to weakly acidic gut pH of Coleoptera (de Maagd et al., 2001). For the midgut and the hindgut of CBB, values between pH 4.5

and 5.2 were consistently observed (Valencia et al., 2000). This result suggests that there is an important activity determinant in selleck inhibitor domain II of Cry1Ba, although it may be a nonspecific binding. For this reason, further study of CBB physiological conditions and mutagenesis Megestrol Acetate site-directed in this toxin and other related Cry proteins is necessary.

The authors are grateful to Dr Ruud A. de Maagd for his participation to this project and the critical discussion of this paper. This work was supported by Dirección de Investigación de la Universidad Nacional de Colombia sede Bogotá (Colombia). S.A.L.-P. gratefully acknowledges Colciencias for his PhD fellowship. “
“The SbmA protein is involved in the transport of MccB17-, MccJ25-, bleomycin- and proline-rich peptides into the Escherichia coli cytoplasm. sbmA gene homologues were found in a variety of bacteria. However, the physiological role of this protein still remains unknown. Previously, we found that a combination of sbmA and tolC mutations in Tn10-carrying E. coli K-12 strains results in hypersusceptibility to tetracycline. In this work, we studied sbmA expression in a tolC mutant background and observed an increased expression throughout growth. We ruled out the global transcriptional regulator RpoS and the small RNA micF as intermediates in this regulation. The tolC mutation induced the expression of other well-characterized strong σE-dependent promoters in E. coli.