cDNA cloning, functional expression, and characterization of chicken sulfotransferases belonging to the SULT1B and SULT1C families

A search of the chicken expressed sequence tag (EST) database identified 2 cDNA clones that appeared to represent members of the SULT1B and SULT1C enzyme families. These cDNAs were fully sequenced and found to contain full-length inserts. Phylogenetic analysis of the derived amino acid sequences clearly placed them as the first members of the chicken SULT1B and SULT1C families, respectively, to be identified, and we propose they be named SULT1B1 and SULT1C1. (CHICK)SULT1B1 shares approximately 60% amino acid sequence identity with mammalian SULT1B enzymes, whereas the closest neighbor to (CHICK)SULT1C1 was the ortholog (RAT)SULT1C1, with 68% identity. We cloned these cDNAs into the bacterial expression vectors from the pET series. Transformed Escherichia coli cells strongly expressed the recombinant proteins. Purification of the recombinant enzymes from E. coli was accomplished by a three-step procedure involving ammonium sulfate precipitation, anion exchange chromatography, and affinity chromatography. The purified enzymes displayed subunit molecular weights of approximately 35,000Da on SDS-PAGE, as predicted, and were both able to sulfate a wide range of compounds, including xenobiotics and endogenous substrates such as iodothyronines. Detailed kinetic analysis showed SULT1C1 was more prolific in that it was able to sulfate dopamine, tyramine, and apomorphine, which SULT1B1 was not. 2-Bromophenol was the best substrate for both enzymes. We also raised antibodies against these proteins, which were able to detect the SULTs by ELISA, and which were able to strongly inhibit the recombinant enzymes. This is the first detailed characterization of sulfotransferases from the chicken, and it demonstrates that the avian and mammalian SULT1 enzymes are closely related in both structure and function.     

Ca2+ binding protects against gelsolin amyloidosis

Amyloid diseases occur when native or mutant polypeptides misfold and aggregate to form deposits in the extracellular space. There are at least 20 proteins associated with amyloid diseases, including the well-known amyloid-beta peptide that is the causative agent for Alzheimer's disease (AD). This review describes familial amyloidosis of Finnish type (FAF), an amyloid disease caused by mutations in plasma gelsolin, a secreted protein that contains multiple Ca2+-binding domains. The FAF mutations result in a loss of the Ca2+-binding site in domain 2 of plasma gelsolin. The resulting decreased stability gives rise to susceptibility to the protease furin in the Golgi. Furin cleavage generates a secreted fragment that undergoes a second proteolytic event in the extracellular matrix to produce a peptide that self-assembles into amyloid plaques. Thus, Ca2+ binding in native plasma gelsolin protects against amyloid disease.     

Hydrolysis of Nothogenia erinacea xylan by xylanases from families 10 and 11

The structures of several enzymatic hydrolysis products of Nothogenia erinacea seaweed xylan, a linear homopolymer with mixed beta-(1-->3)/beta-(1-->4) linkages, were analysed by physicochemical and biochemical techniques. With the glycoside hydrolase family 10 beta-(1-->4)-xylanase from Cryptococcus adeliae, hydrolysis proceeds to a final mixture of products containing a mixed linkage-type triose as a major compound, whereas with the family 11 xylanase from Thermomyces lanuginosus this is a mixed linkage tetraose. The Cryptococcus xylanase is shown to be capable of also catalysing the hydrolysis of beta-(1-->3) linkages, that is this of a mixed type tetraose intermediary formed, in accordance with the broader substrate specificity of family 10 enzymes. From a partial degradation experiment with the T. lanuginosus xylanase, a series of higher mixed oligosaccharides were isolated and identified. The observed oligosaccharide intermediates and splicing pattern indicate an irregular beta-(1-->3)/beta-(1-->4) linkage distribution within the linear d-xylose polymer. Similar results were obtained with rhodymenan, the seaweed xylan from Palmares palmata.