Overexpression of Sterol Carrier Protein 2 in Patients with Hereditary Cholesterol Gallstones

<p>Abstract</p> <p>Background</p> <p>Lithogenic bile is the major cause of cholesterol gallstone, but its pathogenesis is not well understood. The hypersecretion of biliary cholesterol is believed to be an important cause of lithogenic bile. Sterol Carrier Protein 2 (SCP2) participates in cholesterol trafficking and lipid metabolism in hepatocytes and may play a key role in cholesterol gallstone formation.</p> <p>Methods</p> <p>21 cholesterol gallstone genealogies were studied to investigate the expression of SCP2 gene in liver tissue of hereditary and non-hereditary cholesterol gallstone patients as well as non-gallstone patients. The mRNA expression of liver SCP2 in 28 hereditary patients, 30 non-hereditary cholesterol gallstone patients and 32 non-gallstone patients was measured by Reverse Transcription Polymerase Chain Reaction (RT-PCR). The protein expression of liver SCP2 was also detected in all the patients by Western blotting. At the same time, the bile was also analyzed with biochemical techniques and the Cholesterol Saturation Index (CSI) was calculated.</p> <p>Results</p> <p>The mRNA and protein expression of SCP2 was significantly increased in cholesterol gallstone patients compared to those of non-gallstone patients. Moreover, SCP2 was expressed at higher levels in hereditary cholesterol gallstone patients than that of non-hereditary cholesterol gallstone patients. There was significant difference observed in CSI between cholesterol gallstone patients and non-gallstone patients, but not in CSI between hereditary and non-hereditary cholesterol gallstone patients.</p> <p>Conclusions</p> <p>SCP2 was overexpressed in hereditary cholesterol gallstone patients compared to non-hereditary cholesterol gallstone patients. This finding indicated that SCP2 might be one of the genetic factors contributing to cholesterol gallstone formation, which was always accompanied by the increase of bile lithogenicity.</p

Bacteriochlorophyll c formation via the C5 pathway of 5-aminolevulinic acid synthesis in Chloroflexus aurantiacus

AbstractBiosynthesis of 5-aminolevulinic acid (ALA) in Chloroflexus aurantiacus, a thermophilic bacterium forming bacterioclorophyll c, is shown to proceed via the C5 pathway by demonstrating (1) the specific labeling of its chlorin ring with [1-13C] glutamate and (2) the enzyme activity to produce ALA from glutamate in a cell-free extract. From the phylogenetic distribution it is suggested that ALA synthase distributed in some aerobic eubacteria could be monophyletic in origin

Biosynthesis of vitamin B(12): Concerning the identity of the two-carbon fragment eliminated during anaerobic formation of cobyrinic acid

It has been proved that, during anaerobic biosynthesis of the corrin macrocycle, the two-carbon fragment excised from the precursor, precorrin-3, is acetaldehyde, which originates from C-20 and its attached methyl group. This apparently contradictory finding is rationalized in terms of the subsequent enzymatic oxidation of acetaldehyde to acetic acid, which was previously regarded as the volatile fragment released by the action of the biosynthetic enzymes of Propionibacterium shermanii. The observation that acetaldehyde (rather than acetic acid) is extruded during anaerobic B(12) synthesis is in full accord with the structure of factor IV, a new intermediate on the pathway

OBSERVATION OF ENZYME BOUND INTERMEDIATES IN THE BIOSYNTHESIS OF PREUROPORPHYRINOGEN BY PBG DEAMINASE

Electrospray mass spectrometry was used to observe covalently bound enzyme-intermediate complexes during the catalytic assembly of the linear tetrapyrrole, preuroporphyrinogen, by the enzyme porphobilinogen deaminase. Electrospray mass spectrometry was used to observe covalently bound enzyme-intermediate complexes during the catalytic assembly of the linear tetrapyrrole, preuroporphyrinogen, by the enzyme porphobilinogen deaminase. © 1991

Cloning, sequencing, and expression of the uroporphyrinogen III methyltransferase cobA gene of Propionibacterium freudenreichii (shermanii).

We cloned, sequenced, and overexpressed cobA, the gene encoding uroporphyrinogen III methyltransferase in Propionibacterium freudenreichii, and examined the catalytic properties of the enzyme. The methyltransferase is similar in mass (27 kDa) and homologous to the one isolated from Pseudomonas denitrificans. In contrast to the much larger isoenzyme encoded by the cysG gene of Escherichia coli (52 kDa), the P. freudenreichii enzyme does not contain the additional 22-kDa peptide moiety at its N-terminal end bearing the oxidase-ferrochelatase activity responsible for the conversion of dihydrosirohydrochlorin (precorrin-2) to siroheme. Since it does not contain this moiety, it is not a likely candidate for synthesis of a cobalt-containing early intermediate that has been proposed for the vitamin B12 biosynthetic pathway in P. freudenreichii. Uroporphyrinogen III methyltransferase of P. freudenreichii not only catalyzes the addition of two methyl groups to uroporphyrinogen III to afford the early vitamin B12 intermediate, precorrin-2, but also has an overmethylation property that catalyzes the synthesis of several tri- and tetra-methylated compounds that are not part of the vitamin B12 pathway. The enzyme catalyzes the addition of three methyl groups to uroporphyrinogen I to form trimethylpyrrocorphin, the intermediate necessary for biosynthesis of the natural products, factors S1 and S3, previously isolated from this organism. A second gene found upstream from the cobA gene encodes a protein homologous to CbiO of Salmonella typhimurium, a membrane-bound, ATP-dependent transport protein thought to be part of the cobalt transport system involved in vitamin B12 synthesis. These two genes do not appear to constitute part of an extensive cobalamin operon