Wild-type and feedback-resistant phosphoribosyl pyrophosphate synthetases from Bacillus amyloliquefaciens: purification, characterization, and application to increase purine nucleoside production.

Bacillus strains are used for the industrial production of the purine nucleosides inosine and guanosine, which are raw materials for the synthesis of the flavor enhancers disodium inosinate and disodium guanylate. An important precursor of purine nucleosides is 5-phospho-α-D: -ribosyl-1-pyrophosphate, which is synthesized by phosphoribosyl pyrophosphate synthetase (PRS, EC 2.7.

Completion of the mapping of transcription start sites for the five-gene block subgenomic RNAs of Beet yellows Closterovirus and identification of putative subgenomic promoters.

In the positive-sense RNA genome of Beet yellows Closterovirus (BYV), the 3'-terminal open reading frames (ORFs) 2-8 are expressed as a nested set of subgenomic (sg) RNAs. ORFs 2-6, coding for the structural and movement proteins, form a 'five-gene block' conserved in closteroviruses. We mapped the 5'-end of the ORF 4 sgRNA, which encodes the p64 protein, at adenosine-11169 in the BYV genome.

The yicM (nepI) gene of Escherichia coli encodes a major facilitator superfamily protein involved in efflux of purine ribonucleosides.

The yicM gene of Escherichia coli was found by selection for resistance to 6-mercaptopurine. Translation and transcription initiation sites of yicM were determined. Overexpression of yicM increased resistance of sensitive cells to inosine and guanosine, decreased E.

Identification and characterization of the new gene rhtA involved in threonine and homoserine efflux in Escherichia coli.

The rhtA gene known as the ybiF ORF in the genome of Escherichia coli was identified as a new gene involved in threonine and homoserine efflux. This gene encodes a highly hydrophobic membrane protein that contains 10 predicted transmembrane segments. The rhtA23 mutation, which is an A-for-G substitution at position -1 in relation to the ATG start codon, increases the expression level of the rhtA gene.

Ultrastructural localization and epitope mapping of the methyltransferase-like and helicase-like proteins of Beet yellows virus.

Monoclonal antibodies (MAbs) specific to the methyltransferase (MT) and helicase (HEL) domains of the closterovirus Beet yellows virus (BYV) were used for immunogold labelling of ultrathin sections of virus-infected Tetragonia expansa plants. MAbs 4A2 and 4A5 from the MT panel, and 1C4 from the HEL panel, specifically labelled distinct closterovirus-induced membranous structures, the 'BYV-type vesicles', thus suggesting that the closterovirus MT-like and HEL-like proteins co-localize in these structures. Probing of the MT and HEL MAbs with synthetic octapeptides spanning the sequences of the recombinant MT and HEL fragments that had been used as immunogens showed that 4A5 and 4A2 recognized a single epitope, SRLLENET (aa 686-692 in the BYV 1a protein), and 1C4 reacted with the DDPF epitope (aa 2493-2496).