Regulation of succinoglycan and galactoglucan biosynthesis in Sinorhizobium meliloti.

Sinorhizobium meliloti (Rhizobium meliloti) 2011 has the ability to produce the two acidic exopolysaccharides succinoglycan (EPS I) and galactoglucan (EPS II). EPS I is a branched heteropolysaccharide composed of octasaccharide repeating units, whereas EPS II is a linear heteropolysaccharide consisting of disaccharide subunits. The exo-exs and exp gene clusters are involved in the biosynthesis of EPSI and EPSII, respectively.

Growth characteristics and influence of antibiotics on rough/smooth phenotypic variants of Helicobacter pylori.

Helicobacter pylori shows a rather high variability of several biochemical markers including lipopolysaccharide structures. This study aimed to determine whether Helicobacter pylori has a potential for phenotypic variability and to describe its effects on bacterial pathogenesis. From colonies of three clinical strains of Helicobacter pylori with rough (R) colony morphology, spontaneous phenotypic variants with smooth (S) colony morphology were isolated that occurred with a frequency of 10(-2) to 10(-3), irrespective of growth conditions.

The Sinorhizobium meliloti MucR protein, which is essential for the production of high-molecular-weight succinoglycan exopolysaccharide, binds to short DNA regions upstream of exoH and exoY.

Sinorhizobium meliloti (Rhizobium meliloti) is able to produce two different exopolysaccharides, succinoglycan and galactoglucan. Mutations in the mucR gene of S. meliloti result in the stimulation of galactoglucan synthesis, while the type of succinoglycan produced is modified.

The regulatory protein MucR binds to a short DNA region located upstream of the mucR coding region in Rhizobium meliloti.

The Rhizobium meliloti MucR protein is known to regulate the biosynthesis of the two exopolysaccharides, succinoglycan and galactoglucan. The mucR gene was successfully overexpressed in Escherichia coli BL21 cells by heat shock induction using a two-plasmid system. Cell extracts of the production strain contained about 20% of a polypeptide of 17 kDa apparent molecular mass, corresponding to the size expected for MucR.