Manganese is highly effective in protecting cells from cadmium intoxication.

Cadmium poisoning results in cell death. Although several intracellular pathways have been identified in this response, transport systems responsible for cadmium entry into cells remain poorly understood and controversial. Here, we analyzed the effects of several divalent cations on cadmium toxicity in different cell types.

Low dose cadmium poisoning results in sustained ERK phosphorylation and caspase activation.

Cadmium poisoning has been known to result in a wide variety of cellular responses, including oxidative stress and kinase activation. It has been reported that ERK is activated following acute cadmium exposure, and this response is commonly seen as a classical ERK survival mechanism. Here, we analyzed different cell types for their responses to low concentrations of cadmium poisoning.

Development of a new bicistronic retroviral vector with strong IRES activity.

Background: Internal Ribosome Entry Site (IRES)-based bicistronic vectors are important tools in today's cell biology. Among applications, the expression of two proteins under the control of a unique promoter permits the monitoring of expression of a protein whose biological function is being investigated through the observation of an easily detectable tracer, such as Green Fluorescent Protein (GFP). However, analysis of published results making use of bicistronic vectors indicates that the efficiency of the IRES-controlled expression can vary widely from one vector to another, despite their apparent identical IRES sequences.

Functional expression of Sinorhizobium meliloti BetS, a high-affinity betaine transporter, in Bradyrhizobium japonicum USDA110.

Among the Rhizobiaceae, Bradyrhizobium japonicum strain USDA110 appears to be extremely salt sensitive, and the presence of glycine betaine cannot restore its growth in medium with an increased osmolarity (E. Boncompagni, M. Osteras, M.

The Sinorhizobium meliloti ABC transporter Cho is highly specific for choline and expressed in bacteroids from Medicago sativa nodules.

In Sinorhizobium meliloti, choline is the direct precursor of phosphatidylcholine, a major lipid membrane component in the Rhizobiaceae family, and glycine betaine, an important osmoprotectant. Moreover, choline is an efficient energy source which supports growth. Using a PCR strategy, we identified three chromosomal genes (choXWV) which encode components of an ABC transporter: ChoX (binding protein), ChoW (permease), and ChoV (ATPase).

The Sinorhizobium meliloti glycine betaine biosynthetic genes (betlCBA) are induced by choline and highly expressed in bacteroids.

The symbiotic soil bacterium Sinorhizobium meliloti has the capacity to synthesize the osmoprotectant glycine betaine from choline-O-sulfate and choline. This pathway is encoded by the betICBA locus, which comprises a regulatory gene, betI, and three structural genes, betC (choline sulfatase), betB (betaine aldehyde dehydrogenase), and betA (choline dehydrogenase). Here, we report that betICBA genes constitute a single operon, despite the existence of intergenic regions containing mosaic elements between betI and betC, and betB and betA.

BetS is a major glycine betaine/proline betaine transporter required for early osmotic adjustment in Sinorhizobium meliloti.

Hybridization to a PCR product derived from conserved betaine choline carnitine transporter (BCCT) sequences led to the identification of a 3.4-kb Sinorhizobium meliloti DNA segment encoding a protein (BetS) that displays significant sequence identities to the choline transporter BetT of Escherichia coli (34%) and to the glycine betaine transporter OpuD of Bacillus subtilis (30%). Although the BetS protein shows a common structure with BCCT systems, it possesses an unusually long hydrophilic C-terminal extension (169 amino acids).

Molecular characterization of the bet genes encoding glycine betaine synthesis in Sinorhizobium meliloti 102F34.

As a first step towards the elucidation of the molecular mechanisms responsible for the utilization of choline and glycine betaine (betaine) either as carbon and nitrogen sources or as osmoprotectants in Sinorhizobium meliloti, we selected a Tn5 mutant, LTS23-1020, which failed to grow on choline but grew on betaine. The mutant was deficient in choline dehydrogenase (CDH) activity, failed to oxidize [methyl-14C]choline to [methyl-14C]betaine, and did not use choline, but still used betaine, as an osmoprotectant. The Tn5 mutation in LTS23-1020 was complemented by plasmid pCHO34, isolated from a genomic bank of S.