Structural Distortions and Decentralized Fiscal Policies in EMU

The combination of discretionary monetary policy, labor-market distortions and nominal wage rigidity yields an inflation bias as monetary policy tries to exploit nominal wage contracts to address labour-market distortions Although an inflation target eliminates this inflation bias, it creates a conflict between monetary policy and discretionary fiscal policy if fiscal policy is set at a higher frequency than nominal wages are. To avoid the associated excessive accumulation of public debt, ceilings on public debt are called for. If countries differ substantially in terms of structural distortions or economic shocks, uniform debt ceilings must be complemented by country-specific debt targets in order to prevent decentralised fiscal authorities from employing debt policy strategically.Discretionary monetary policy, wage rigidity, decentralized fiscal policy, monetary union, inflation targets, debt targets

Monetary union without fiscal coordination may discipline policymakers

We show that, with benevolent policymakers and fiscal leadership, monetary unification reduces inflation, taxes and public spending. These disciplining effects of a monetary union, which rise with the number of fiscal players in the union, are likely to raise welfare. Joining an optimally designed monetary union is particularly attractive if fiscal authorities do not care about inflation. Fiscal coordination offsets the disciplining effects of monetary unification. Hence, subsidiarity in fiscal policymaking may enhance welfare. Keywords: monetary union, fiscal leadership, common central bank, discipline, optimal institutions, inflation, taxation, spending, fiscal coordination.international economics and trade ;

The role of public debt in the game of double chicken

This paper explores how debt accumulation is affected by the strategic interactions between monetary and fiscal authorities. To achieve the second best with a dependent central bank, the government needs to be made both more conservative and more impatient. However, in the absence of political distortions, an optimally designed conservative, independent central bank is sufficient to establish the second best. In the presence of political distortions, however, also an optimal debt target is needed. Keywords: Central bank independence, price stability weights, (optimal) debt targets, strategic debt management, political distortions, optimal preferences.public economics ;

The Promise of Defined Ambition Plans: Lessons for the United States

We explore Dutch proposals for defined ambition plans in an occupational pension context. Firms no longer act as external risk sponsors but continue to provide a distributional platform for pensions, thereby addressing behavioral and agency issues as well as imperfections of insurance and financial markets. Pension entitlements are defined in terms of (deferred) annuities, and participants share the risks of assets and a joint liability pool on the basis of complete contracts. We investigate risk management and valuation of these plans, explore their strengths and weaknesses, and analyze whether such plans hold promise for the United States

Transcriptional Activation of Biosynthetic Gene Clusters in Filamentous Fungi

Filamentous fungi are highly productive cell factories, many of which are industrial producers of enzymes, organic acids, and secondary metabolites. The increasing number of sequenced fungal genomes revealed a vast and unexplored biosynthetic potential in the form of transcriptionally silent secondary metabolite biosynthetic gene clusters (BGCs). Various strategies have been carried out to explore and mine this untapped source of bioactive molecules, and with the advent of synthetic biology, novel applications, and tools have been developed for filamentous fungi. Here we summarize approaches aiming for the expression of endogenous or exogenous natural product BGCs, including synthetic transcription factors, assembly of artificial transcription units, gene cluster refactoring, fungal shuttle vectors, and platform strains

Nonribosomal peptide synthetases and their biotechnological potential in Penicillium rubens

Nonribosomal peptide synthetases (NRPSs) are large multimodular enzymes that synthesize a diverse variety of peptides. Many of these are currently used as pharmaceuticals, thanks to their activity as antimicrobials (penicillin, vancomycin, daptomycin, echinocandin), immunosuppressant (cyclosporin) and anticancer compounds (bleomycin). Because of their biotechnological potential, NRPSs have been extensively studied in the past decades. In this review, we provide an overview of the main structural and functional features of these enzymes, and we consider the challenges and prospects of engineering NRPSs for the synthesis of novel compounds. Furthermore, we discuss secondary metabolism and NRP synthesis in the filamentous fungus Penicillium rubens and examine its potential for the production of novel and modified β-lactam antibiotics

Biochemical characterization of the Nocardia lactamdurans ACV synthetase

The L-δ-(α-aminoadipoyl)-L-cysteinyl-D-valine synthetase (ACVS) is a nonribosomal peptide synthetase (NRPS) that fulfills a crucial role in the synthesis of β-lactams. Although some of the enzymological aspects of this enzyme have been elucidated, its large size, at over 400 kDa, has hampered heterologous expression and stable purification attempts. Here we have successfully overexpressed the Nocardia lactamdurans ACVS in E. coli HM0079. The protein was purified to homogeneity and characterized for tripeptide formation with a focus on the substrate specificity of the three modules. The first L-α-aminoadipic acid-activating module is highly specific, whereas the modules for L-cysteine and L-valine are more promiscuous. Engineering of the first module of ACVS confirmed the strict specificity observed towards its substrate, which can be understood in terms of the non-canonical peptide bond position

Trade-offs between tRNA abundance and mRNA secondary structure support smoothing of translation elongation rate

Translation of protein from mRNA is a complex multi-step process that occurs at a non-uniform rate. Variability in ribosome speed along an mRNA enables refinement of the proteome and plays a critical role in protein biogenesis. Detailed single protein studies have found both tRNA abundance and mRNA secondary structure as key modulators of translation elongation rate, but recent genome-wide ribosome profiling experiments have not observed significant influence of either on translation efficiency. Here we provide evidence that this results from an inherent trade-off between these factors. We find codons pairing to high-abundance tRNAs are preferentially used in regions of high secondary structure content, while codons read by significantly less abundant tRNAs are located in lowly structured regions. By considering long stretches of high and low mRNA secondary structure in Saccharomyces cerevisiae and Escherichia coli and comparing them to randomized-gene models and experimental expression data, we were able to distinguish clear selective pressures and increased protein expression for specific codon choices. The trade-off between secondary structure and tRNA-concentration based codon choice allows for compensation of their independent effects on translation, helping to smooth overall translational speed and reducing the chance of potentially detrimental points of excessively slow or fast ribosome movement.European Commission (Marie-Curie Actions Initial Training Network for Integrated Cellular Homeostasis (NICHE) project 289384

A Minimal Model of Ribosome Allocation Dynamics Captures Trade-offs in Expression between Endogenous and Synthetic Genes

Cells contain a finite set of resources that must be distributed across many processes to ensure survival. Among them, the largest proportion of cellular resources is dedicated to protein translation. Synthetic biology often exploits these resources to execute orthogonal genetic circuits, yet the burden this places on the cell is rarely considered. Here, we develop a minimal model of ribosome allocation dynamics capturing the demands on translation when expressing a synthetic construct together with endogenous genes required for maintenance of cell physiology. Critically, it contains three key variables related to design parameters of the synthetic construct covering: transcript abundance, translation initiation rate, and elongation time. We show that model-predicted changes in ribosome allocation closely match experimental shifts in synthetic protein expression rate and cellular growth. Intriguingly, the model is also able to accurately infer transcript levels and translation times after further exposure to additional ambient stress. Our results demonstrate that a simple model of resource allocation faithfully captures the redistribution of protein synthesis resources when faced with the burden of synthetic gene expression and environmental stress. The tractable nature of the model makes it a versatile tool for exploring the guiding principles of efficient heterologous expression and the indirect interactions that can arise between synthetic circuits and their host chassis due to competition for shared translational resources

Impact of classical strain improvement of penicillium rubens on amino acid metabolism during β-Lactam production

To produce high levels of β-lactams, the filamentous fungus Penicillium rubens (previously named Penicillium chrysogenum) has been subjected to an extensive classical strain improvement (CSI) program during the last few decades. This has led to the accumulation of many mutations that were spread over the genome. Detailed analysis reveals that several mutations targeted genes that encode enzymes involved in amino acid metabolism, in particular biosynthesis of L-cysteine, one of the amino acids used for β-lactam production. To examine the impact of the mutations on enzyme function, the respective genes with and without the mutations were cloned and expressed in Escherichia coli, purified, and enzymatically analyzed. Mutations severely impaired the activities of a threonine and serine deaminase, and this inactivates metabolic pathways that compete for L-cysteine biosynthesis. Tryptophan synthase, which converts L-serine into L-tryptophan, was inactivated by a mutation, whereas a mutation in 5-aminolevulinate synthase, which utilizes glycine, was without an effect. Importantly, CSI caused increased expression levels of a set of genes directly involved in cysteine biosynthesis. These results suggest that CSI has resulted in improved cysteine biosynthesis by the inactivation of the enzymatic conversions that directly compete for resources with the cysteine biosynthetic pathway, consistent with the notion that cysteine is a key component during penicillin production. IMPORTANCE Penicillium rubens is an important industrial producer of β-lactam antibiotics. High levels of penicillin production were enforced through extensive mutagenesis during a classical strain improvement (CSI) program over 70 years. Several mutations targeted amino acid metabolism and resulted in enhanced L-cysteine biosynthesis. This work provides a molecular explanation for the interrelation between secondary metabolite production and amino acid metabolism and how classical strain improvement has resulted in improved production strains