Special Issue "Protein Toxins as Proteases"
A special issue of Toxins (ISSN 2072-6651).
Deadline for manuscript submissions: closed (31 March 2010)
Prof. Dr. Shin-ichi Miyoshi (Website)
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University 1-1-1, Tsushima-Naka, Kita-Ku, Okayama-City, Okayama 700-8530, Japan
Fax: +81 86 251 7926
Interests: bacterial protein toxins; pore-forming toxins; cell membrane proteins/receptors; proteolytic enzymes
Proteases are enzymes that hydrolyze a peptide bond in proteins and peptides. The enzymes are essential for the homeostatic control in both eukaryotes and prokaryotes; however, they produced by pathogenic microorganisms occasionally act as toxic factors to the host. Although proteases are classified into four groups, aspartic, cysteine, serine and metallo-proteases, many of the toxic proteases are metallo-proteases containing a zinc (II) ion in the catalytic center. The progress in molecular biology has provided much information on the DNA-derived amino acid sequences for metallo-proteases and has revealed the consensus sequence His-Glu-X-X-His as the zinc-binding motif. This motif was found in clostridial neurotoxins, Bacteroides fragilis enterotoxin (Fragilysin) and Bacillus anthracis lethal factor. These bacterial toxins show remarkably specific proteolytic actions toward a target host protein. For instance, clostridial neurotoxins can cleave the protein components of the neuroexocytosis machinery, which leads to the blockade of neurotransmitter release and consequent muscle paralysis. Hemorrhagic toxins from snake venoms are also metallo-protease. A novel cytotoxin from some enterohemorrhagic Escherichia coli strains consists of one A subunit and five B subunits. The A subunit is a subtilase-like serine protease. This special issue deals with various aspects of protein toxins acting as proteases, which include biochemical and pathological properties, molecular modes of the toxic actions, the development of inhibitors to prevent or interrupt the toxic actions, and application to the cell biology.
Prof. Dr. Shin-ichi Miyoshi
- serine protease
- bacterial protein toxin
- hemorrhagic toxin
- molecular tool