A broad spectrum Kunitz type serine protease inhibitor secreted by the hookworm Ancylostoma ceylanicum.
Although blood-feeding hookworms infect over a billion people worldwide, little is known about the molecular mechanisms through which these parasitic nematodes cause gastrointestinal hemorrhage and iron deficiency anemia. A cDNA corresponding to a secreted Kunitz type serine protease inhibitor has been cloned from adult Ancylostoma ceylanicum hookworm RNA. The translated sequence of the A. ceylanicum Kunitz type inhibitor 1 (AceKI-1) cDNA predicts a 16-amino acid secretory signal sequence, followed by a 68-amino acid mature protein with a molecular mass of 7889 daltons. Recombinant protein (rAceKI-1) was purified from induced lysates of Escherichia coli transformed with the rAceKI-1/pET 28a plasmid, and in vitro studies demonstrate that rAceKI-1 is a tight binding inhibitor of the serine proteases chymotrypsin, pancreatic elastase, neutrophil elastase, and trypsin. AceKI-1 inhibitory activity is present in soluble protein extracts and excretory/secretory products of adult hookworms but not the infective third stage larvae. The native AceKI-1 inhibitor has been purified to homogeneity from soluble extracts of adult A. ceylanicum using size exclusion and reverse-phase high pressure liquid chromatography. As a potent inhibitor of mammalian intestinal proteases, AceKI-1 may play a role in parasite survival and the pathogenesis of hookworm anemia.
Milstone
A M
AM
Infectious Diseases Section, Yale Child Health Research Center, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06520-8081, USA.
Harrison
L M
LM
Bungiro
R D
RD
Kuzmic
P
P
Cappello
M
M
D000595:Amino Acid Sequence; D000722:Ancylostoma; D000818:Animals; D001483:Base Sequence; D006868:Hydrolysis; D008969:Molecular Sequence Data; D015842:Serine Proteinase Inhibitors / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology
D015842:Serine Proteinase Inhibitors