In silico analysis of the two trehalose-6-phosphate synthases (OtsA) encoded by the R. etli genome. (A) Genomic context of the otsAch (chromosomal) and otsAs (plasmid p42a) genes, and construction of an otsAch mutant. otsAch was inactivated by the insertion of a Bam HI (Bm)-digested Ω cassette, which carried resistance genes for streptomycin/spectinomycin, into its unique site Bgl II (Bg), giving the plasmid pMotsA6 (see text for details). (B) Neighbor-joining tree based on OtsA proteins from α-, β-,γ and δ-proteobacteria. The tree is drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree. The Bacteroides/Chlorobi representative S. ruber was used as outgroup. The evolutionary distances were computed using the Poisson correction method and are in the units of the number of amino acid substitutions per site. The rate variation among sites was modeled with a gamma distribution (shape parameter = 1). All positions containing gaps and missing data were eliminated from the dataset (complete deletion option). Bootstrap probabilities (as percentage) were determined from 1000 resamplings.