The complete genome sequence of Staphylothermus marinus reveals differences in sulfur metabolism among heterotrophic Crenarchaeota

<p>Abstract</p> <p>Background</p> <p><it>Staphylothermus marinus </it>is an anaerobic, sulfur-reducing peptide fermenter of the archaeal phylum Crenarchaeota. It is the third heterotrophic, obligate sulfur reducing crenarchaeote to be sequenced and provides an opportunity for comparative analysis of the three genomes.</p> <p>Results</p> <p>The 1.57 Mbp genome of the hyperthermophilic crenarchaeote <it>Staphylothermus marinus </it>has been completely sequenced. The main energy generating pathways likely involve 2-oxoacid:ferredoxin oxidoreductases and ADP-forming acetyl-CoA synthases. <it>S. marinus </it>possesses several enzymes not present in other crenarchaeotes including a sodium ion-translocating decarboxylase likely to be involved in amino acid degradation. <it>S. marinus </it>lacks sulfur-reducing enzymes present in the other two sulfur-reducing crenarchaeotes that have been sequenced – <it>Thermofilum pendens </it>and <it>Hyperthermus butylicus</it>. Instead it has three operons similar to the <it>mbh </it>and <it>mbx </it>operons of <it>Pyrococcus furiosus</it>, which may play a role in sulfur reduction and/or hydrogen production. The two marine organisms, <it>S. marinus </it>and <it>H. butylicus</it>, possess more sodium-dependent transporters than <it>T. pendens </it>and use symporters for potassium uptake while <it>T. pendens </it>uses an ATP-dependent potassium transporter. <it>T. pendens </it>has adapted to a nutrient-rich environment while <it>H. butylicus </it>is adapted to a nutrient-poor environment, and <it>S. marinus </it>lies between these two extremes.</p> <p>Conclusion</p> <p>The three heterotrophic sulfur-reducing crenarchaeotes have adapted to their habitats, terrestrial vs. marine, via their transporter content, and they have also adapted to environments with differing levels of nutrients. Despite the fact that they all use sulfur as an electron acceptor, they are likely to have different pathways for sulfur reduction.</p

Novel Insights into the Diversity of Catabolic Metabolism from Ten Haloarchaeal Genomes

BACKGROUND: The extremely halophilic archaea are present worldwide in saline environments and have important biotechnological applications. Ten complete genomes of haloarchaea are now available, providing an opportunity for comparative analysis. METHODOLOGY/PRINCIPAL FINDINGS: We report here the comparative analysis of five newly sequenced haloarchaeal genomes with five previously published ones. Whole genome trees based on protein sequences provide strong support for deep relationships between the ten organisms. Using a soft clustering approach, we identified 887 protein clusters present in all halophiles. Of these core clusters, 112 are not found in any other archaea and therefore constitute the haloarchaeal signature. Four of the halophiles were isolated from water, and four were isolated from soil or sediment. Although there are few habitat-specific clusters, the soil/sediment halophiles tend to have greater capacity for polysaccharide degradation, siderophore synthesis, and cell wall modification. Halorhabdus utahensis and Haloterrigena turkmenica encode over forty glycosyl hydrolases each, and may be capable of breaking down naturally occurring complex carbohydrates. H. utahensis is specialized for growth on carbohydrates and has few amino acid degradation pathways. It uses the non-oxidative pentose phosphate pathway instead of the oxidative pathway, giving it more flexibility in the metabolism of pentoses. CONCLUSIONS: These new genomes expand our understanding of haloarchaeal catabolic pathways, providing a basis for further experimental analysis, especially with regard to carbohydrate metabolism. Halophilic glycosyl hydrolases for use in biofuel production are more likely to be found in halophiles isolated from soil or sediment

Real exchange rates and transition economies

In a number of empirical studies, transition economies have been shown to be subject to the Harrod-Balassa-Samuelson effect. This implies that the currencies of these countries have experienced a prolonged appreciation in real terms as their convergence proceeded. In this paper we find that a long-run relationship exists between the real exchange rate, productivity differentials, real interest rate differentials and the capital account for eight transition economies of Central and Eastern Europe, using monthly data over a period which extends from 1996 to 2013. We find that there are two sources of appreciation of the currencies of these countries, namely the Harrod-Balassa-Samuelson effect and the capital account effect, and argue that their significance depends on the type of investment received by the countries. While long-run foreign direct investment enhances productivity, porfolio investment leaves productivity unaffected, so our argument is that the larger foreign direct investment relative to portfolio investment, the greater the contribution of productivity in the determination of the real exchange rate. Moreover, we find that while the variables are linked by a linear long-run equilibrium relationship, adjustment towards equilibrium is nonlinear and is well represented by a smooth transition mechanism where the degree of equilibrium correction is a function of the sign and/or the size of the deviation from equilibrium. Interestingly, we find that a logistic smooth transition model fits well a larger number of countries, by allowing a different response of the real exchange rate to misalignments of different sign

US Monetary Regimes and Optimal Monetary Policy in the Euro Area

Monetary policy in the United States has been documented to have switched from reacting weakly to inflation fluctuations during the 1970s, to fighting inflation aggressively from the early 1980s onward. In this paper, I analyze the impact of the U.S. monetary policy regime switches on the Eurozone. I construct a New Keynesian two‐country model where foreign (U.S.) monetary policy switches regimes over time. I estimate the model for the U.S. and the Euro Area using quarterly data and find that the United States has switched between those two regimes, in line with existing evidence. I show that foreign regime switches affect home (Eurozone) inflation and output volatility and their responses to shocks, substantially, as long as the home central bank commits to a time‐invariant interest rate rule reacting to domestic conditions only. Optimal policy in the home country instead requires that the home central bank reacts strongly to domestic producer‐price inflation and to international variables, such as imported goods relative prices. In fact, I show that currency misalignments and relative prices play a crucial role in the transmission of foreign monetary policy regime switches internationally. Interestingly, I show that only marginal gains arise for the Euro Area when the European Central Bank (ECB) adjusts its policy according to the monetary regime in the United States. Thus, a simple time‐invariant monetary policy rule with a strong reaction to Producer Price Index (PPI) inflation and relative prices is enough to counteract the effects of monetary policy switches in the United States