Expression of sterol 12alpha-hydroxylase alters bile acid pool composition in primary rat hepatocytes and in vivo.

Background & Aims: The rate of 12alpha-hydroxylation of bile acid intermediates is believed to determine the ratio of cholic acid (CA) to chenodeoxycholic acid (CDCA) biosynthesis and the overall hydrophobicity of the bile acid pool. The aim of this study was to determine the effects of the level of expression of sterol 12alpha-hydroxylase (CYP8b1) and cholesterol 7alpha-hydroxylase (CYP7a1) on rates of CA biosynthesis and bile acid pool composition.

Methods: Expression of CYP8b1 and CYP7a1 was accomplished through infection of primary rat hepatocytes (PRH) or intact male SD rats with replication-defective recombinant adenoviruses encoding either CYP8b1 or CYP7a1.

Characterization of the serogroup O11 O-antigen locus of Pseudomonas aeruginosa PA103.

We previously cloned a genomic DNA fragment from the serogroup O11 Pseudomonas aeruginosa strain PA103 that contained all genes necessary for O-antigen synthesis and directed the expression of serogroup O11 antigen on recombinant Escherichia coli and Salmonella. To elucidate the pathway of serogroup O11 antigen synthesis, the nucleotide sequence of the biosynthetic genes was determined. Eleven open reading frames likely to be involved in serogroup O11 O-antigen biosynthesis were identified and are designated in order as wzzPaO111 (wzz from P.

Cloning of the glutamyl-tRNA synthetase (gltX) gene from Pseudomonas aeruginosa.

The glutamyl-tRNA synthetase (gltX) gene from Pseudomonas aeruginosa was identified. A plasmid containing a 2.3-kb insert complemented the temperature-sensitive gltX mutation of Escherichia coli JP1449, and GltX activity was demonstrated.

Multiple transcribed elements control expression of the Escherichia coli btuB gene.

Repression by vitamin B12 of the cobalamin transport protein BtuB in the outer membrane of Escherichia coli operates at both the transcriptional and translational levels and is controlled by transcribed sequences within the leader and proximal portion of the btuB coding sequence. The effects of deletions from either end of this region on repression and expression were determined with lac fusions. An element at the 5' end of the transcript and the putative attenuator within the coding sequence were required for transcriptional repression.

Characterization of the baiH gene encoding a bile acid-inducible NADH:flavin oxidoreductase from Eubacterium sp. strain VPI 12708.

A cholate-inducible, NADH-dependent flavin oxidoreductase from the intestinal bacterium Eubacterium sp. strain VPI 12708 was purified 372-fold to apparent electrophoretic homogeneity. The subunit and native molecular weights were estimated to be 72,000 and 210,000, respectively, suggesting a homotrimeric organization.