Dual promoters control expression of the Bacillus anthracis virulence factor AtxA.
ABSTRACT The AtxA virulence regulator of Bacillus anthracis is required for toxin and capsule gene expression. AtxA is a phosphotransferase system regulatory domain-containing protein whose activity is regulated by phosphorylation/dephosphorylation of conserved histidine residues. Here we report that transcription of the atxA gene occurs from two independent promoters, P1 (previously described by Dai et al. [Z. Dai, J. C. Sirard, M. Mock, and T. M. Koehler, Mol. Microbiol. 16:1171-1181, 1995]) and P2, whose transcription start sites are separated by 650 bp. Both promoters have -10 and -35 consensus sequences compatible with recognition by sigma(A)-containing RNA polymerase, and neither promoter depends on the sporulation sigma factor SigH. The dual promoter activity and the extended untranslated mRNA suggest that as-yet-unknown regulatory mechanisms may act on this region to influence the level of AtxA in the cell.
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ABSTRACT: Solitary fibrous tumors of the pleura (SFTP) are very rare neoplasms. The majority of these tumors are benign, but about 10-20 % fulfill the criteria of malignancy. The clinical presentation varies according to the size and intrathoracic localization. In early stages, often asymptomatic, the tumors may grow to an enormous size and then cause symptoms such as cough, chest pain and dyspnea, but also paraneoplastic syndromes such as hypoglycemia or digital clubbing. Between 1981 and June 1998 we treated in our institution 16 SFTP in 14 patients (4 M, 10 F, average age at first operation 58 years). Eight patients showed symptoms, whereas in the other cases the tumors were found on routine chest X-rays. The usually pedunculated SFTP were completely resected without complications. Two patients developed malignant recurrences, which infiltrated the right upper lung lobe and the diaphragm respectively. In these cases the tumor was resected together with the adjacent structures. Since late recurrences are more often malignant than primary SFTPs long-term follow-up is mandatory even in benign lesions.Der Chirurg 09/1999; 70(8):949-52. · 0.70 Impact Factor
Article: A broad-host-range mobilizable shuttle vector for the construction of transcriptional fusions to beta-galactosidase in gram-positive bacteria.[show abstract] [hide abstract]
ABSTRACT: A low-copy-number vector designated pTCV-lac has been constructed to provide a convenient system to analyze regulatory elements in Gram-positive bacteria. The main components of this vector are: (i) the origins of replication of pACYC184 and of the broad-host-range enterococcal plasmid pAM beta 1, (ii) erythromycin- and kanamycin-resistance-encoding genes for selection in Gram-negative and Gram-positive bacteria, (iii) the transfer origin of the IncP plasmid RK2, and (iv) a promoterless beta-galactosidase-encoding lacZ gene with a Gram-positive ribosome binding site. This 12 kb plasmid is present in Gram-positive hosts in three to five copies per chromosome equivalent and contains three unique cloning sites (EcoRI, SmaI, BamHI) for cloning of DNA inserts upstream of the lacZ gene. Plasmid pTCV-lac and derivatives carrying different promoter fragments have been transferred by conjugation from an Escherichia coli IncP mobilizing donor strain to Bacillus subtilis, Listeria monocytogenes, Enterococcus faecalis, and Streptococcus agalactiae. These plasmids were structurally stable in these hosts and the corresponding promoter activities, quantitated by the determination of the beta-galactosidase specific activities, were found to cover at least a 100-fold range in beta-galactosidase values. These results indicate that pTCV-lac should be useful for analysis of gene regulation in a wide range of Gram-positive bacteria.FEMS Microbiology Letters 11/1997; 156(2):193-8. · 2.04 Impact Factor