Characterization of the Bacillus subtilis spore morphogenetic coat protein CotO.

Bacillus spores are protected by a structurally and biochemically complex protein shell composed of over 50 polypeptide species, called the coat. Coat assembly in Bacillus subtilis serves as a relatively tractable model for the study of the formation of more complex macromolecular structures and organelles. It is also a critical model for the discovery of strategies to decontaminate B. anthracis spores. In B. subtilis, a subset of coat proteins is known to have important roles in assembly. Here we show that the recently identified B. subtilis coat protein CotO (YjbX) has an especially important morphogenetic role. We used electron and atomic force microscopy to show that CotO controls assembly of the coat layers and coat surface topography as well as biochemical and cell-biological analyses to identify coat proteins whose assembly is CotO dependent. cotO spores are defective in germination and partially sensitive to lysozyme. As a whole, these phenotypes resemble those resulting from a mutation in the coat protein gene cotH. Nonetheless, the roles of CotH and CotO and the proteins whose assembly they direct are not identical. Based on fluorescence and electron microscopy, we suggest that CotO resides in the outer coat (although not on the coat surface). We propose that CotO and CotH participate in a late phase of coat assembly. We further speculate that an important role of these proteins is ensuring that polymerization of the outer coat layers occurs in such a manner that contiguous shells, and not unproductive aggregates, are formed.

A three-protein inhibitor of polar septation during sporulation in Bacillus subtilis.

We present evidence for a three-protein inhibitor of polar division that locks in asymmetry after the formation of a polar septum during sporulation in Bacillus subtilis. Asymmetric division involves the formation of cytokinetic Z-rings near both poles of the developing cell. Next, a septum is formed at one of the two polar Z-rings, thereby generating a small, forespore cell and a mother cell. Gene expression under the control of the mother-cell transcription factor sigmaE is needed to block cytokinesis at the pole distal to the newly formed septum. We report that this block in polar cytokinesis is mediated partly by sigmaE-directed transcription of spoIID, spoIIM and spoIIP, sporulation genes that were known to be involved in the subsequent process of forespore engulfment. We find that a spoIID, spoIIM and spoIIP triple mutant substantially mimicked the bipolar division phenotype of a sigmaE mutant and that cells engineered to produce SpoIID, SpoIIM and SpoIIP prematurely were inhibited in septum formation at both poles. Consistent with the hypothesis that SpoIID, SpoIIM and SpoIIP function at both poles of the sporangium, a GFP--SpoIIM fusion localized to the membrane that surrounds the engulfed forespore and to the potential division site at the distal pole.

The transcriptional profile of early to middle sporulation in Bacillus subtilis.

Spore formation by Bacillus subtilis is governed by global changes in gene transcription. We used nylon-substrate DNA arrays representing approximately 96% of the predicted open reading frames in the B. subtilis chromosome to compare the pattern of transcripts from wild-type cells with the pattern from cells mutant for the sporulation transcription factors Spo0A or final sigma(F). We found 520 genes whose transcript levels were at least 3-fold dependent on Spo0A but not on final sigma(F), and an additional 66 genes whose transcript levels were dependent upon both regulatory proteins. Two strategies were used to help assign genes to the direct control of a particular developmental regulatory protein. In one approach, we analyzed the effects on global gene expression of artificially producing a constitutively active form of Spo0A during growth. In a second approach, Hidden Markov models were used to identify promoters likely to be activated by Spo0A, final sigma(F), or a third sporulation transcription factor, final sigma(E). In addition to detecting known sporulation genes, we identified many genes of unknown function whose patterns of expression and regulation suggest that they could be involved in sporulation. Disruption of two such newly identified genes, yabP and yabQ, blocked sporulation at a late stage.

Structural kinetics of transcription activation at the malT promoter of Escherichia coli by UV laser footprinting.

We have studied the kinetics of transcriptional initiation and activation at the malT and malTp1 promoters of Escherichia coli using UV laser footprinting. Contrary to previous studies and because of the very rapid signal acquisition by this technique, we can obtain structural information about true reaction intermediates of transcription initiation. The consequences of adding a transcriptional activator, the cAMP receptor protein/cAMP complex (CRP), are monitored in real time, permitting us to assign specific interactions to the activation of discrete steps in transcription initiation. Direct protein-protein contacts between CRP and the RNA polymerase appeared very rapidly, followed by DNA melting around the -10 hexamer. CRP slightly increased the rate of this isomerization reaction but, more importantly, favored the establishment of additional contacts between the DNA upstream of the CRP binding site and RNA polymerase subsequent to open complex formation. These contacts make a major contribution to transcriptional activation by stabilizing open forms of the promoter complex, thereby indirectly accelerating promoter escape. The ensemble of the kinetic, structural signals demonstrated directly that CRP exerts most of its activating effects on the late stages of transcriptional initiation at the malT promoter.

Influence of the location of the cAMP receptor protein binding site on the geometry of a transcriptional activation complex in Escherichia coli.

The interactions between the cAMP receptor protein (CRP) and RNA polymerase during transcriptional activation at the Escherichia coli malT promoter have been analyzed using a combination of footprinting methods. We show that a closed complex is formed at this promoter in the absence of activator and that CRP merely stabilizes the open complex. The alpha-subunits of the RNA polymerase are involved in this effect as shown by KMnO4 footprinting. The open complex formed in the presence of CRP is structurally identical to the one found at a CRP-independent promoter up-mutant. UV-laser footprinting yields distinct signals for the different protein-DNA interactions within the complex and for interactions between CRP and RNA polymerase. We monitor these signals in promoter variants that place the CRP binding site at different distances upstream of the start site of transcription. Signals within the core promoter region, as well as those located just upstream of the -35 hexamer, are unaffected by the position of the CRP binding site. Contacts of RNA polymerase with the upstream promoter region change in a mutant RNA polymerase containing a truncated alpha-subunit. We conclude that at least one of the alpha-subunits of RNA polymerase binds to DNA upstream of the -35 hexamer and that this interaction is unaffected by the position of the CRP binding site. We discuss models that account for the different activities of CRP in transcriptional activation as a function of promoter geometry.

Influence of DNA geometry on transcriptional activation in Escherichia coli.

Transcription from many Escherichia coli promoters can be activated by the cAMP-CRP complex bound at different locations upstream of the promoter. At some locations the mechanism of activation involves direct protein-protein contacts between CRP and the RNA polymerase. We positioned the CRP binding site at various distances from the transcription start site of the malT promoter and measured the in vivo activities of these promoter variants. From the activation profiles we deduce that the protein-protein interactions involved in transcriptional activation are rather rigid. A heterologous protein (IHF) that bends the DNA to a similar degree as does CRP activates transcription when bound at sites equivalent to activating positions for CRP. DNA geometry makes a major contribution to the process of transcriptional activation and DNA upstream of the activator binding site participates in this process. Removal of this DNA decreases the capacity of the malT promoter to be activated by CRP in vitro. We conclude that both DNA topology and direct protein-protein contacts contribute to transcriptional activation and that the relative importance of these two modes of activation depends on the nature of the activator and on the location of the activator binding site.

Purification of a 28 kD non-aggregating tryptic peptide of the Duffy blood group protein.

Duffy blood group antigenic epitopes are located on a 35-43 kD integral membrane protein of the erythrocyte membrane. This protein functions as a receptor for the human malaria parasite, Plasmodium vivax. The Duffy protein has been difficult to purify because of its tendency to form aggregates. Here we describe purification of a 28 kD tryptic fragment of the Duffy protein and purification of an 18 kD de-glycosylated form of the Duffy tryptic peptide using Thiopropyl Sepharose 6B chromatography and preparative SDS-PAGE. These Duffy-reactive peptides do not form aggregates and may prove amendable to protein sequencing.

Short-lasting accumulation in osteoid bone seams of radioactive iron injected as citrate into mice.

The possible role in vivo of osseous structures in binding radioactive iron injected as a low-molecular-weight complex was studied in mice, using combined autoradiography and histomorphometry on sections of undecalcified, plastic-embedded femur epiphyses/metaphyses. A single intraperitoneal injection of 10 microCi 59Fe (1.2 micrograms Fe) per animal as citrate within 3 hours led to a preferential accumulation of this metal in the osteoid mineralized tissue interphase (osteoid seams) of bone. Within the next 2 days the labeling intensity in this localization diminished markedly to approximate levels of the bone marrow and calcified bone. The bulk of the injected radioiron was utilized according to known erythrokinetics. Findings suggest a direct entry of "free," ie, not transferrin-bound, iron into osteoid seams and its consecutive rapid removal from this site.

Treatment and relapse prophylaxis of duodenal ulcer with pirenzepine and cimetidine.

The effect of pirenzepine and cimetidine on healing, symptoms and relapse rate of duodenal ulcer was studied in a placebo-controlled double-blind trial. Cimetidine (1 g daily) was superior at the beginning of therapy to a low dose of pirenzepine (75 mg daily) and placebo with regard to symptoms. No significant differences in ulcer healing were found between the 3 groups of treatment. The relapse rate after treatment with pirenzepine was lower than after treatment with cimetidine.

[Treatment and prevention of recurrence of duodenal ulcer with pirenzepin and cimetidine]. / Behandlung und Rezidivprophylaxe des Ulcus duodeni mit Pirenzepin und Cimetidin.

The effect of pirenzepine and cimetidine on healing, symptoms, and relapse rate of duodenal ulcer was studied in a placebo controlled double blind trial. With regard to symptoms, cimetidine (1 g daily) was superior at the beginning of therapy to a low dose of pirenzepine (75 mg daily) and to placebo. No significant differences in ulcer healing were found between the 3 treatment groups. The relapse rate after treatment with pirenzepine was lower than after treatment with cimetidine.

Effect of ranitidine on gastric acid and pepsin secretion following sham feeding.

The effect of oral ranitidine 150 mg on the acid and pepsin response to sham feeding or pentagastrin was examined in healthy volunteers in a double-blind randomized trial. Gastric juice was collected up to 255 min after ingestion of the drug. In placebo treated subjects, basal acid secretion rate and the secretion rate following sham feeding and injection of 6 micrograms kg-1 of pentagastrin were 5.3 +/- 2.0 S.E.M., 12.3 +/- 3.2, and 24.4 +/- 5.4 mmol h-1, respectively. The corresponding values in ranitidine treated subjects were 0.1 +/- 0.1, 0.5 +/- 0.2, and 3.4 +/- 1.2, respectively. The reduction of acid secretion in all three instances is statistically significant (p less than 0.025, p less than 0.05, and p less than 0.05, respectively). Basal, sham feeding stimulated, and pentagastrin stimulated pepsin secretion rates in the placebo treated group were 38.4 +/- 7.0 S.E.M., 68.6 +/- 13.2, and 39.2 +/- 8.0 mg h-1, respectively. In the ranitidine treated group, the values were 5.0 +/- 3.4, 13.2 +/- 5.6, and 19.6 +/- 6.0, respectively. The reduction of pepsin secretion during basal state and following sham feeding is statistically significant (p less than 0.005 and p less than 0.01). Thus, oral ranitidine inhibits the acid and pepsin response to sham feeding in man. Its inhibitory effect on the acid response to pentagastrin lasts for at least 4 h.

Ranitidine inhibits gastric acid and pepsin secretion following sham feeding.

The effect of an oral therapeutic dose of 150 mg of ranitidine on the acid and pepsin response to sham feeding and pentagastrin was examined in healthy volunteers, using a double-blind random-isation method. Gastric juice was collected up to 255 minutes after ingestion of the drug. In placebo-treated subjects, basal acid secretion rate and the secretion rate following sham feeding and injection of 6 micrograms/kg of pentagastrin were 5.3 meq/h +/- 2.0 SEM, 12.3 +/- 3.2, and 24.4 +/- 5.4, respectively. The corresponding values in ranitidine-treated subjects were 0.1 +/- 0.1, 0.5 +/- 0.2, and 3.4 +/- 1.2, respectively. The reduction of acid secretion in all three instances is statistically significant (p less than 0.025, p less than 0.05, and p less than 0.05, respectively). Basal, sham feeding-stimulated, and pentagastrin-stimulated pepsin secretion rates in the placebo-treated group were 38.4 mg/h +/- 7.0 SEM, 68.6 +/- 13.2, and 39.2 +/- 8.0, respectively. In the ranitidine-treated group, the values were 5.0 +/- 3.4, 13.2 +/- 5.6, and 19.6 +/- 5.0, respectively. The reduction of pepsin secretion during basal state and following sham feeding is statistically significant (p less than 0.005 and p less than 0.01). Thus, oral ranitidine inhibits the acid and pepsin response to sham feeding in man. Its inhibitory effect on the acid response to pentagastrin lasts for at least 4 hours.

Gardner's syndrome with glandular cysts of the fundic mucosa.

The present study describes a family (mother and son) with Gardner's syndrome. Aside from the classical findings, gastric polyposis was found; histologically glandular cysts of the fundic mucosa were diagnosed. The occurrence of gastric polyps in Gardner's syndrome has recently been described with increasing frequency. These lesions have various histological aspects. A number of authors have noted several cases of Gardner's syndrome with glandular cysts of the fundic mucosa, but to our knowledge this is the first case of familial occurrence.

[Papillomatosis coronae glandis. Frequency of occurrence and clinical picture]. / Papillomatosis coronae glandis. Häufigkeit und klinisches Bild.

The clinical picture of pearly penile papules (PPP) is described on the basis of the literature and the authors' own investigations. Although symptomless and without functional significance, PPP may lead to damaging therapeutic measures if not recognized as such by physician and patient. The incidence of PPP has been investigated in 642 19-year-old Swiss men originating from the same geographical region. PPP were found in 33%, in 9.2% as the major variant and in 23.8% as the minor variant.