Isolation, partial purification, and characterization of a novel petromyzonol sulfotransferase from Petromyzon marinus (lamprey) larval liver

Bile acid production is life-stage and sex-dependent and affected by primer pheromones in the sea lamprey

Pheromonal bile salts are important for sea lampreys (Petromyzon marinus Linnaeus) to complete their life cycle. The synthesis and release of a releaser/primer pheromone 3-keto petromyzonol sulfate (3kPZS) by spermiating males have been well characterized. 3kPZS evokes sexual behaviors in ovulatory females, induces immediate 3kPZS release in spermiating males, and elicits neuroendocrine responses in prespawning adults. Another primer pheromone released by spermiating males, 3-keto allocholic acid (3kACA), antagonizes the neuroendocrine effects of 3kPZS in prespermiating males. However, the effects of 3kACA and 3kPZS on pheromone production in prespawning adults is unclear. To understand the foundation of pheromone production, we examined sea lamprey bile salt levels at different life stages. To investigate the priming effects of 3kACA and 3kPZS, we exposed prespawning adults with vehicle or synthetic 3kACA or 3kPZS. We hypothesized that endogenous bile salt levels were life-stage and sex-dependent, and differentially affected by 3kACA and 3kPZS in prespawning adults. Using ultra-performance liquid chromatography tandem mass spectrometry, we found that sea lampreys contained distinct mixtures of bile salts in the liver and plasma at different life stages. Males usually contained higher amounts of bile salts than females. Petromyzonamine disulfate was the most abundant C27 bile salt and petromyzonol sulfate was the most abundant C24 bile salt. Waterborne 3kACA and 3kPZS exerted differential effects on bile salt production in the liver and gill, their circulation and clearance in the plasma, and their release into water. We conclude that bile salt levels are life-stage and sex-dependent and differentially affected by primer pheromones.

Sterol Sulfates and Sulfotransferases in Marine Diatoms

Sterol sulfates are widely occurring molecules in marine organisms. Their importance has been so far underestimated although many of these compounds are crucial mediators of physiological and ecological functions in other organisms. Biosynthesis of sterol sulfates is controlled by cytosolic sulfotransferases (SULTs), a varied family of enzymes that catalyze the transfer of a sulfo residue (-SO₃H) from the universal donor 3'-phosphoadenosine-5'-phosphosulfate to the hydroxyl function at C-3 of the steroid skeleton. The absence of molecular tools has been the main impediment to the development of a biosynthetic study of this class of compounds in marine organisms. In fact, there is very limited information about these enzymes in marine environments. SULT activity has, however, been reported in several marine species, and, recently, the production of sterol sulfates has been linked to the control of growth in marine diatoms. In this chapter, we describe methods for the study of sterol sulfates in this lineage of marine microalgae. The main aim is to provide the tools useful to deal with the biosynthesis and regulation of these compounds and to circumvent the bottleneck of the lack of molecular information. The protocols have been designed for marine diatoms, but most of the procedures can be used for other marine organisms.

Transcriptomic profiling of male European eel (Anguilla anguilla) livers at sexual maturity

The European eel Anguilla anguilla has a complex life cycle that includes freshwater, seawater and morphologically distinct stages as well as two extreme long distance migrations. Eels do not feed as they migrate across the Atlantic to the Sargasso Sea but nevertheless reach sexual maturity before spawning. It is not yet clear how existing energy stores are used to reach the appropriate developmental state for reproduction. Since the liver is involved in energy metabolism, protein biosynthesis and endocrine regulation it is expected to play a key role in the regulation of reproductive development. We therefore used microarrays to identify genes that may be involved in this process. Using this approach, we identified 231 genes that were expressed at higher and 111 genes that were expressed at lower levels in sexually mature compared with immature males. The up-regulated set includes genes involved in lipid metabolism, fatty acid synthesis and transport, mitochondrial function, steroid transport and bile acid metabolism. Several genes with putative enzyme functions were also expressed at higher levels at sexual maturity while genes involved in immune system processes and protein biosynthesis tended to be down-regulated at this stage. By using a high-throughput approach, we have identified a subset of genes that may be linked with the mobilization of energy stores for sexual maturation and migration. These results contribute to an improved understanding of eel reproductive biology and provide insight into the role of the liver in other teleosts with a long distance spawning migrations.

Cloning and Expression of a Novel Sulfotransferase with Unique Substrate Specificity fromBombyx mori

We identified a cDNA encoding a putative cytosolic sulfotransferase (SULT) by searching the expressed sequence tag database of Bombyx mori, and subsequently obtained the full-length cDNA for this gene via rapid amplification of cDNA ends (RACE). We designated this gene bmST1, and showed by sequence analysis that it belongs to a novel SULT family. The tissue specificity of bmST1 mRNA expression was examined in fifth instar larvae by reverse transcriptase-polymerase chain reaction (RT-PCR), and transcripts were detectable in the silk gland, gut, fat body, and Malpighian tube. A recombinant form of bmST1 was then expressed using a gluthathione S-transferase (GST) gene fusion system, and it was purified from Escherichia coli. Purified bmST1 did not exhibit sulfating activity toward SULT substrates such as 4-nitrophenol, vanillin, hydroxysteroids, or monoamines. Surprisingly, however, recombinant bmST1 showed considerable activity toward 4-nitrocatechol and also gallate esters, although the catechins are not sulfated by this enzyme.

Cloning, expression, and characterization of cytosolic sulfotransferase isozymes from Drosophila melanogaster

We have identified four cytosolic sulfotransferase (SULT) homologs in the genome database of Drosophila melanogaster, and have designated these genes dmST1-4. Each of these four isozymes was subsequently classified into a different and novel gene family, as determined by the low amino acid sequence homology (less than 40%) between them, and also toward their vertebrate homologs. The transcripts for these four SULT homologs were detectable at all developmental stages in D. melanogaster. In addition, three of these isozymes, the exception being dmST2, were successfully expressed and purified in Escherichia coli. These recombinant dmST1, 3, and 4 products showed high sulfating activity toward phenolic compounds such as vanillin and 4-nitrophenol, but showed no activity toward typical endogenous substrates such as tyramine and serotonin. DmST4 and dmST3 showed the lowest and highest K(m) values for 3'-phosphoadenosine-5'-phosphosulfate (PAPS) respectively. DmST4 also showed low but not negligible activity toward 20-hydroxyecdysone.

A Novel Sulfotransferase Abundantly Expressed in the Dauer Larvae of Caenorhabditis elegans

We have isolated a gene (clone Y113G7A.11) from Caenorhabditis elegans (C. elegans), that we have designated as ceST1, and which is the only member of the cytosolic sulfotransferase (SULT) gene family present in the genome of this organism. We identified the SULT motifs of ceST1 based upon their deduced amino acid sequence, and subsequently expressed the ceST1 cDNA in Escherichia coli and characterized its enzymatic properties. The recombinant protein showed sulfation activity for 4-nitrophenol and 2-naphthol substrates, but did not catalyze the sulfation of either monoamines or hydroxysteroids. Another compound sulfated by ceST1 is bisphenol A, which is known to stimulate germ cell proliferation in C. elegans. SULT activity was not detected in the cytosol of C. elegans, probably due to heat labile inhibitors. The ceST1 protein was detectable in the cytosol of C. elegans using anti-sera raised against recombinant ceST1, and transcripts could also be detected throughout the developmental stages. Moreover, high levels of ceST1 expression were evident at both the embryonic and adult stages and were augmented in dauer larva. These findings suggest that this sulfotransferase either forms part of a defence system against xenobiotics or regulates germ cell proliferation in C. elegans.

Petromyzonol sulfate and its derivatives: the chemoattractants of the sea lamprey

Petromyzonol sulfate (PZS) and 3 keto-PZS are bile alocohol derivatives that serve as chemoattractants during the life cycle of sea lamprey (Petromyzon marinus). The sulfonate moiety is crucial perhaps conferring the required solubility for the pheromone that is released into the streams and for the specificity to bind to its receptor. During the life cycle of lamprey, larvae produce copious amounts of 5 alpha-cholan-PZS, and trace amounts of allocholic acid (ACA), which attracts adults to the same breeding ground. Later the spermeating males produce 3keto-PZS, and trace amounts of 3-keto-ACA, which attracts the ovulating females, signaling both its reproductive status and its nesting location for successful reproduction. In both stages, a mixture of components serves as pheromone plume, similar to insects. The receptors for the migratory and the reproductive pheromones need to be molecularly cloned and characterized in order to understand the molecular biology of olfaction in the sea lamprey.

Sulfation and glucuronidation of phenols: implications in coenyzme Q metabolism

Phase II conjugation of phenolic compounds constitutes an important mechanism through which exogenous or endogenous toxins are detoxified and excreted. Species differences in the rates of glucuronidation or sulfation can lead to significant variation in the metabolism of this class of compounds. Conjugation of the hydroxyl groups of phenols can occur with glucuronate or sulfate. Quinone metabolism, deactivation, and detoxification are also affected by the same conjugatory systems as phenols; however, reduction of quinones to hydroquinols seems to be a prerequisite. This work reviews current knowledge on phenol conjugation and its implications on hydroquinone metabolism with special consideration for coenzyme Q metabolism.