This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Poole, K Articles by Braun, V Search for Related Content PubMed PubMed Citation Articles by Poole, K Articles by Braun, V

 Previous Article  |  Next Article 

Infect Immun. 1988 November; 56(11): 2967-2971

Iron regulation of Serratia marcescens hemolysin gene expression.

Mikrobiologie II, Universität Tübingen, Federal Republic of Germany.

ABSTRACT

The hemolytic activity of Serratia marcescens was examined as a function of iron availability. Restriction of iron by the nonmetabolizable chelator 2,2'-dipyridyl or the iron-binding protein transferrin produced a marked increase in hemolytic activity. The hemolytic activity of S. marcescens is determined by two adjacent genes, 5'-shlB-shlA-3', where shlA encodes the hemolysin which requires the ShlB protein for activity. A gene fusion between the promoter-proximal portion of shlA and phoA, the Escherichia coli alkaline phosphatase gene, was subcloned into a medium-copy-number vector, and the recombinant plasmid was introduced into S. marcescens. The expression of shlA was measured as a function of alkaline phosphatase activity, which increased threefold under iron-restricted conditions. Removal of the 5' noncoding region upstream of shlB in the fusion vector resulted in a 10-fold decrease in alkaline phosphatase activity under iron-sufficient conditions, with no effect of iron limitation on this residual activity. This suggested that the site mediating iron regulation of shlA expression occurs upstream of shlB. Consistent with this, we observed iron-regulated synthesis of the ShlB protein in Western immunoblots of isolated outer membranes. The hemolysin determinant was subsequently expressed on a medium-copy-number vector in fur+/fur isogenic strains of E. coli K-12, where a 10-fold-higher activity was observed in the mutant strain compared with the wild type. A sequence exhibiting some homology to the Fur-binding consensus sequence was identified upstream of the shlB coding region, overlapping the -35 region of a putative promoter.

This article has been cited by other articles:

• Robertson, K. P., Smith, C. J., Gough, A. M., Rocha, E. R. (2006). Characterization of Bacteroides fragilis Hemolysins and Regulation and Synergistic Interactions of HlyA and HlyB. Infect. Immun. 74: 2304-2316 [Abstract] [Full Text]  
• Brillard, J., Duchaud, E., Boemare, N., Kunst, F., Givaudan, A. (2002). The PhlA Hemolysin from the Entomopathogenic Bacterium Photorhabdusluminescens Belongs to the Two-Partner Secretion Family of Hemolysins. J. Bacteriol. 184: 3871-3878 [Abstract] [Full Text]  
• Ochsner, U. A., Johnson, Z., Vasil, M. L. (2000). Genetics and regulation of two distinct haem-uptake systems, phu and has, in Pseudomonas aeruginosa. Microbiology 146: 185-198 [Abstract] [Full Text]  
• Wood, G. E., Dutro, S. M., Totten, P. A. (1999). Target Cell Range of Haemophilus ducreyi Hemolysin and Its Involvement in Invasion of Human Epithelial Cells. Infect. Immun. 67: 3740-3749 [Abstract] [Full Text]  
• Litwin, C. M., Byrne, B. L. (1998). Cloning and Characterization of an Outer Membrane Protein of Vibrio vulnificus Required for Heme Utilization: Regulation of Expression and Determination of the Gene Sequence. Infect. Immun. 66: 3134-3141 [Abstract] [Full Text]