Global transcriptional control by glucose and carbon regulator CcpA in Clostridium difficile.

International audienceThe catabolite control protein CcpA is a pleiotropic regulator that mediates the global transcriptional response to rapidly catabolizable carbohydrates, like glucose in Gram-positive bacteria. By whole transcriptome analyses, we characterized glucose-dependent and CcpA-dependent gene regulation in Clostridium difficile. About 18% of all C. difficile genes are regulated by glucose, for which 50% depend on CcpA for regulation. The CcpA regulon comprises genes involved in sugar uptake, fermentation and amino acids metabolism, confirming the role of CcpA as a link between carbon and nitrogen pathways. Using combination of chromatin immunoprecipitation and genome sequence analysis, we detected 55 CcpA binding sites corresponding to ∼140 genes directly controlled by CcpA. We defined the C. difficile CcpA consensus binding site (cre(CD) motif), that is, 'RRGAAAANGTTTTCWW'. Binding of purified CcpA protein to 19 target cre(CD) sites was demonstrated by electrophoretic mobility shift assay. CcpA also directly represses key factors in early steps of sporulation (Spo0A and SigF). Furthermore, the C. difficile toxin genes (tcdA and tcdB) and their regulators (tcdR and tcdC) are direct CcpA targets. Finally, CcpA controls a complex and extended regulatory network through the modulation of a large set of regulators

Catalyzing Privacy Law

The United States famously lacks a comprehensive federal data privacy law. In the past year, however, over half the states have proposed broad privacy bills or have established task forces to propose possible privacy legislation. Meanwhile, congressional committees are holding hearings on multiple privacy bills. What is catalyzing this legislative momentum? Some believe that Europe’s General Data Protection Regulation (GDPR), which came into force in 2018, is the driving factor. But with the California Consumer Privacy Act (CCPA) which took effect in January 2020, California has emerged as an alternate contender in the race to set the new standard for privacy.Our close comparison of the GDPR and California’s privacy law reveals that the California law is not GDPR-lite: it retains a fundamentally American approach to information privacy. Reviewing the literature on regulatory competition, we argue that California, not Brussels, is catalyzing privacy law across the United States. And what is happening is not a simple story of powerful state actors. It is more accurately characterized as the result of individual networked norm entrepreneurs, influenced and even empowered by data globalization. Our study helps explain the puzzle of why Europe’s data privacy approach failed to spur US legislation for over two decades. Finally, our study answers critical questions of practical interest to individuals—who will protect my privacy?—and to businesses—whose rules should I follow

Role of glucose and CcpA in capsule expression and virulence of Streptococcus suis

Streptococcus suis is one of the most important pathogens in pigs and is also an emerging zoonotic agent. After crossing the epithelial barrier, S. suis causes bacteraemia, resulting in meningitis, endocarditis and bronchopneumonia. Since the host environment seems to be an important regulatory component for virulence, we related expression of virulence determinants of S. suis to glucose availability during growth and to the sugar metabolism regulator catabolite control protein A (CcpA). We found that expression of the virulence-associated genes arcB, representing arcABC operon expression, cps2A, representing capsular locus expression, as well as sly, ofs, sao and epf, differed significantly between exponential and early stationary growth of a highly virulent serotype 2 strain. Deletion of ccpA altered the expression of the surface-associated virulence factors arcB, sao and eno, as well as the two currently proven virulence factors in pigs, ofs and cps2A, in early exponential growth. Global expression analysis using a cDNA expression array revealed 259 differentially expressed genes in early exponential growth, of which 141 were more highly expressed in the CcpA mutant strain 10¿ccpA and 118 were expressed to a lower extent. Interestingly, among the latter genes, 18 could be related to capsule and cell wall synthesis. Correspondingly, electron microscopy characterization of strain 10¿ccpA revealed a markedly reduced thickness of the capsule. This phenotype correlated with enhanced binding to porcine plasma proteins and a reduced resistance to killing by porcine neutrophils. Taken together, our data demonstrate that CcpA has a significant effect on the capsule synthesis and virulence properties of S. suis

Thermodynamic properties of a tetramer ferro-ferro-antiferro-antiferromagnetic Ising-Heisenberg bond alternating chain as a model system for Cu(3-Clpy)2_2(N3_3)2_2

Thermodynamic properties of a tetramer ferro-ferro-antiferro-antiferromagnetic Ising-Heisenberg bond alternating chain are investigated by the use of an exact mapping transformation technique. Exact results for the magnetization, susceptibility and specific heat in the zero as well as nonzero magnetic field are presented and discussed in detail. The results obtained from the mapping are compared with the relevant experimental data of Cu(3-Clpy)$_2$(N$_3$)$_2$ (3-Clpy=3-Chloropyridine).Comment: 10 pages, 1 table, 14 figures, to be presented at CSMAG04 conferenc

Substrate induction and glucose repression of maltose utilization by Streptomyces coelicolor A3(2) is controlled by malR, a member of the lacI-galR family of regulatory genes

malR of Strepomyces coelicolor A3(2) encodes a homologue of the Lacl/Galr family of repressor proteins, and is divergently transcribed from the malEFG gene cluster, which encodes components of an ATP-dependent transport system that is required for maltose utilization. Transcription of malE was induced by maltose and repressed by glucose. Disruption or deletion of malR resulted in constitutive, glucose-insensitive malE transcription at a level markedly above that observed in the parental malR+ strain, and overproduction of MalR prevented growth on maltose as carbon source. Consequently, MalR plays a crucial role in both substrate induction and glucose repression of maltose utilization. MalR is expressed from a single promoter with transcription initiating at the first G of the predicted GTG translataion start codon

From meadows to milk to mucosa – adaptation of Streptococcus and Lactococcus species to their nutritional environments

Lactic acid bacteria (LAB) are indigenous to food-related habitats as well as associated with the mucosal surfaces of animals. The LAB family Streptococcaceae consists of the genera Lactococcus and Streptococcus. Members of the family include the industrially important species Lactococcus lactis, which has a long history safe use in the fermentative food industry, and the disease-causing streptococci Streptococcus pneumoniae and Streptococcus pyogenes. The central metabolic pathways of the Streptococcaceae family have been extensively studied because of their relevance in the industrial use of some species, as well as their influence on virulence of others. Recent developments in high-throughput proteomic and DNA-microarray techniques, in in vivo NMR studies, and importantly in whole-genome sequencing have resulted in new insights into the metabolism of the Streptococcaceae family. The development of cost-effective high-throughput sequencing has resulted in the publication of numerous whole-genome sequences of lactococcal and streptococcal species. Comparative genomic analysis of these closely related but environmentally diverse species provides insight into the evolution of this family of LAB and shows that the relatively small genomes of members of the Streptococcaceae family have been largely shaped by the nutritionally rich environments they inhabit.

Expression systems for industrial Gram-positive bacteria with low guanine and cytosine content

Recent years have seen an increase in the development of gene expression systems for industrial Gram-positive bacteria with low guanine and cytosine content that belong to the genera Bacillus, Clostridium, Lactococcus, Lactobacillus, Staphylococcus and Streptococcus. In particular, considerable advances have been made in the construction of inducible gene expression systems based on the capacity of these bacteria to utilize specific sugars or to secrete autoinducing peptides that are involved in quorum sensing. These controlled expression systems allow for present and future exploitation of these bacteria as cell factories in medical, agricultural, and food biotechnology.

Concentration risk and the optimal number of central counterparties for a single asset

We model the central counterparty (CCP) clearing of a single asset traded over-the-counter by two groups of banks in two currencies. We compare a variety of different clearing set-ups involving one or two CCPs according to their ability to withstand a combined market and banking crisis. Using stress testing, the model shows that the question of the optimal clearing set-up for a specifi c asset is complex and depends on many parameters such as the level of funding available to the CCP(s), the degree of integration between the different groups of participants and the particular risk profiles of these different groups. On the whole, however, a single CCP solution appears less resilient than a two-CCP arrangement when the magnitude of the crisis is large and only more resilient when the magnitude of the crisis is small in relation to the clearing fund of the CCP(s). Another interesting outcome is that the two-CCP set-ups perform better than the single CCP set-up for low levels of participation.

Software Patents: What One-Click Buy and Safe Air Travel Have in Common

Have you ever sat in an airplane, typing on your laptop, when the darn thing crashes for the one-millionth time? Have you ever then thought about how the airplane you are sitting in is controlled by software, too--the technical term being fly by wire --and then started sweating uncontrollably? Software controls not only air traffic but plenty of other safety-critical technologies: the tightrope walk of controlling the chain reaction of radioactive elements in nuclear power plants; the navigation and activation of missiles;3 the moves and cutting-depth of a surgical laser when correcting eye-sights; the list goes on... With such reliance on software, malfunction due to errors in the program code becomes unacceptable. Software patents help heighten the standard by supporting the re-use of the code of established and tested systems