Identification and characterization of genes (xapA, xapB, and xapR) involved in xanthosine catabolism in Escherichia coli.
AUTOR(ES)
Seeger, C
RESUMO
We have characterized four genes from the 52-min region on the Escherichia coli linkage map. Three of these genes are directly involved in the metabolism of xanthosine, whereas the function of the fourth gene is unknown. One of the genes (xapA) encodes xanthosine phosphorylase. The second gene, named xapB, encodes a polypeptide that shows strong similarity to the nucleoside transport protein NupG. The genes xapA and xapB are located clockwise of a gene identified as xapR, which encodes a positive regulator belonging to the LysR family and is required for the expression of xapA and xapB. The genes xapA and xapB form an operon, and their expression was strictly dependent on the presence of both the XapR protein and the inducer xanthosine. Expression of the xapR gene is constitutive and not autoregulated, unlike the case for many other LysR family proteins. In minicells, the XapB polypeptide was found primarily in the membrane fraction, indicating that XapB is a transport protein like NupG and is involved in the transport of xanthosine.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=177358Documentos Relacionados
- Isolation and Characterization of Mutations in the Escherichia coli Regulatory Protein XapR
- Cloning and characterization of a gene (fadR) involved in regulation of fatty acid metabolism in Escherichia coli.
- Identification of five new essential genes involved in the synthesis of a secreted protein in Escherichia coli.
- Identification of cutC and cutF (nlpE) genes involved in copper tolerance in Escherichia coli.
- Ribose catabolism of Escherichia coli: characterization of the rpiB gene encoding ribose phosphate isomerase B and of the rpiR gene, which is involved in regulation of rpiB expression.