Semi-Autonomous Revenue Authorities in Sub-Saharan Africa: Silver Bullet or White Elephant

A major component of tax administration reform in sub-Saharan Africa for the last 30 years has been the creation of semi-autonomous revenue authorities (SARAs). The effects of their creation on revenue performance have been much debated, although there are only a few quantitative studies. The core argument of this paper is that existing research suggesting diverse and contradictory outcomes has not taken account of trends in revenue performance in the years before the establishment of SARAs. Allowing for this revenue history our analysis based on 46 countries over the period 1980-2015 provides no robust evidence that SARAs induce an increase in revenue performance. This does not imply that SARAs may not provide benefits for tax collection, but they do not demonstrably increase (or decrease) revenue collected

The σ\u3csup\u3eB\u3c/sup\u3e-Dependent Promoter of the \u3ci\u3eBacillus subtilis sigB\u3c/i\u3e Operon Is Induced by Heat Shock

σB, a secondary sigma factor of Bacillus subtilis, was found to increase 5- to 10-fold when cultures were shifted from 37 to 48°C. Western blot (immunoblot) analyses, in which monoclonal antibodies specific for the sigB operon products RsbV, RsbW, and σB were used to probe extracts from wild-type and mutant B. subtilis strains, revealed that all three proteins increased coordinately after heat shock and that this increase was dependent on σB but not RsbV, a positive regulator normally essential for σB-dependent sigB expression. Nuclease protection experiments of RNA synthesized after heat shock supported the notion that the shift to 48°C enhanced transcription from the sigB operon\u27s σB-dependent promoter. The level of mRNA initiating at the σB-dependent ctc promoter was also seen to increase approximately 5- to 10-fold after heat shock. Pulse-labeling of the proteins synthesized after a shift to 48°C demonstrated that sigB wild-type and mutant strains produced the maijor heat-inducible proteins in similar amounts; however, at least seven additional proteins were present after the temperature shift in the wild-type strain but absent in the sigB null mutant. Thus, although σB is not required for the expression of essential heat shock genes, it is activated by heat shock to elevate its own synthesis and possibly the synthesis of several other heat-inducible proteins

Isolation of Bacillus subtilis genes transcribed in vitro and in vivo by a major sporulation-induced, DNA-dependent RNA polymerase.

As a means of determining the function of sigma 29, a sporulation-essential sigma factor, we have isolated and begun to characterize genes that require sigma 29 for their expression. RNA transcribed in vitro from total Bacillus subtilis DNA by using sigma 29-containing RNA polymerase (E-sigma-29) was hybridized to a bank of B. subtilis DNA fragments that had been cloned into bacteriophage lambda. Approximately 0.25% of the cloned B. subtilis DNA fragments displayed detectable hybridization with our RNA probe. Five DNA fragments that had strong in vitro template activity for E-sigma-29 were selected for further study. The DNA fragments which contained in vitro sigma 29 promoter activity encoded RNAs that were synthesized by B. subtilis during sporulation. Mutant B. subtilis that failed to synthesize sigma 29 (spoIIA, spoIIE) made less RNA that could hybridize to these cloned DNAs than did a mutant (spoIIC) which did synthesize sigma 29 but was blocked at a similar stage in development. A detailed analysis of several of the cloned DNAs demonstrated that they encoded RNAs that were transcribed from approximately the same start site in vivo that E-sigma-29 initiated transcription in vitro. These particular transcripts were present only during the period of sigma-29 abundance (2 to 4 h after the onset of sporulation) in sporulating cells which carried a wild-type allele of the sigma-29 structural gene (spoIIG). We conclude that the isolation procedure used in this study identified genes that are transcribed by E-sigma 29, not only in vitro but also in vivo. Preliminary characterization of the cloned genes indicate that they encoded multiple overlapping RNAs which were each synthesized at unique times during growth or sporulation. This result implies that sigma 29 does not activate a unique population of genes with a novel function in sporulation but rather that it has a temporal role in spore gene control, transcribing those genes required to be active during its period of abundance regardless of their specific function

Sporulation Phenotype of a Bacillus subtilis Mutant Expressing an Unprocessable but Active σ(E) Transcription Factor

σ(E), a sporulation-specific sigma factor of Bacillus subtilis, is formed from an inactive precursor (pro-σ(E)) by a developmentally regulated processing reaction that removes 27 amino acids from the proprotein's amino terminus. A sigE variant (sigE335) lacking 15 amino acids of the prosequence is not processed into mature σ(E) but is active without processing. In the present work, we investigated the sporulation defect in sigE335-expressing B. subtilis, asking whether it is the bypass of proprotein processing or a residual inhibition of σ(E) activity that is responsible. Fluorescence microscopy demonstrated that sigE335-expressing B. subtilis progresses further into sporulation (stage III) than do strains lacking σ(E) activity (stage II). Consistent with its stage III phenotype, and a defect in σ(E) activity rather than its timing, the sigE335 allele did not disturb early sporulation gene expression but did inhibit the expression of late sporulation genes (gerE and sspE). The Spo(−) phenotype of sigE335 was found to be recessive to wild-type sigE. In vivo assays of σ(E) activity in sigE, sigE335, and merodiploid strains indicate that the residual prosequence on σ(E335), still impairs its activity to function as a transcription factor. The data suggest that the 11-amino-acid extension on σ(E335) allows it to bind RNA polymerase and direct the resulting holoenzyme to σ(E)-dependent promoters but reduces the enzyme's ability to initiate transcription initiation and/or exit from the promoter

Tethering of the Bacillus subtilis σ(E) Proprotein to the Cell Membrane Is Necessary for Its Processing but Insufficient for Its Stabilization

σ(E), a sporulation-specific transcription factor of Bacillus subtilis, is synthesized as an inactive proprotein with a 27-amino acid extension at its amino terminus. This “pro” sequence is removed by a developmentally regulated protease, but when present, it blocks σ(E) activity, tethers σ(E) to the bacterium's cytoplasmic membrane, and promotes σ(E) stability. To investigate whether pro-σ(E) processing and/or stabilization are tied to membrane sequestration, we used fluorescent protein fusions to examine the membrane binding of SigE variants. The results are consistent with membrane association as a prerequisite for pro-σ(E) processing but not as a sufficient cause for the proprotein's stability

The Growth-Promoting and Stress Response Activities of the Bacillus subtilis GTP Binding Protein Obg Are Separable by Mutation▿

Bacillus subtilis Obg is a ribosome-associating GTP binding protein that is needed for growth, sporulation, and induction of the bacterium's general stress regulon (GSR). It is unclear whether the roles of Obg in sporulation and stress responsiveness are direct or a secondary effect of its growth-promoting functions. The present work addresses this question by an analysis of two obg alleles whose phenotypes argue for direct roles for Obg in each process. The first allele [obg(G92D)] encodes a missense change in the protein's highly conserved “obg fold” region. This mutation impairs cell growth and the ability of Obg to associate with ribosomes but fails to block sporulation or the induction of the GSR. The second obg mutation [obg(Δ22)] replaces the 22-amino-acid carboxy-terminal sequence of Obg with an alternative 26-amino-acid sequence. This Obg variant cofractionates with ribosomes and allows normal growth but blocks sporulation and impairs the induction of the GSR. Additional experiments revealed that the block on sporulation occurs early, preventing the activation of the essential sporulation transcription factor Spo0A, while inhibition of the GSR appears to involve a failure of the protein cascade that normally activates the GSR to effectively catalyze the reactions needed to activate the GSR transcription factor (σB)