Actin enhances the haemolytic activity of Escherichia coli

• Published in: Microbiology (Society for General Microbiology) 1998-07, Vol.144 (7), p.1845-1852
• Main Authors: Basaraba, R. J, Byerly, A. N, Stewart, G. C, Mosier, D. A, Fenwick, B. W, Chengappa, M. M, Laegreid, W. W
• Format: Article
• Language: English
• Subjects: Actins - pharmacology; Alkaline Phosphatase - analysis; Animals; Bacteriology; Biological and medical sciences; Blotting, Western; Cattle; Cloning, Molecular; Escherichia coli; Escherichia coli - drug effects; Escherichia coli - growth & development; Escherichia coli - metabolism; Fundamental and applied biological sciences. Psychology; Hemolysin Proteins - analysis; Hemolysis; Microbiology; Mutagenesis; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Sheep; Swine
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/00221287-144-7-1845

1 Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, VCS Building, 1800 Denison Avenue, Kansas State University, Manhattan, KS 66506--5601, USA 2 United States Meat Animal Research Center, Clay Center, NE, USA Author for correspondence: R. J. Basaraba. Tel: + 1 785 532 4456. Fax: + 1 785 532 4481. ABSTRACT Act in is a major cytoskeletal protein of mammalian muscle and non-muscle cells. Exposure of cells to soluble factors that damage cell membranes results in the release of actin into the extracellular spaces. The -haemolysin (HlyA) of Escherichia coli is the prototype RTX (repeat in toxin) toxin and is thought to be important in virulence because of its ability to lyse cells by formation of pores in the cell membrane. These studies were conducted to determine if actin influences growth and haemolytic activity of E. coli. Growth of E. coli in the presence of actin resulted in culture supernatant haemolytic activity that was 2.4-, 2.7- and 3.3-fold greater than that of E. coli grown in medium containing BSA, non-supplemented medium, or medium containing heat-denatured actin, respectively. The enhanced haemolytic activity occurred only when actin was present during the growth phase and there was no effect when actin was added to culture supernatants containing haemolysin. The increased haemolytic activity by actin was concentration-dependent, detectable in early-exponential-phase growth, and associated with increased concentrations of secreted HlyA by Western blotting. Actin induced a 2.9-fold increase in alkaline phosphatase activity in E. coli CC118 with a TnphoA insertion in the hlyB determinant of the recombinant haemolysin piasmid pWAM04. These results indicate that extracellular actin enhances haemolysin production by E. coli and may have implications in the pathogenesis of E. coli infections. Keywords: actin, Escherichia coli, haemolysin