Cercarial elastase is encoded by a functionally conserved gene family across multiple species of schistosomes.
Water borne cercaria(ae) of the trematode genus Schistosoma rapidly penetrate host skin. A single serine protease activity, cercarial elastase, is deposited in advance of the invading parasite by holocytosis of vesicles from ten large acetabular gland cells. Cercarial elastase activity is a composite of multiple isoforms. Genes coding for the isoforms can be divided into two classes by amino acid and promoter sequence homology. Two of the five genes identified in Schistosoma mansoni account for over 90% of the activity and protein released. The remaining genes produce little protein or are silent. Positional scanning synthetic combinatorial substrate libraries demonstrate that the two major isoforms have similar substrate specificities and are, therefore, isoenzymes. The closely related Schistosoma hematobium and the distantly related Schistosomatium douthitti also contain multiple orthologous cercarial elastase genes suggesting that gene duplication may have occurred after speciation in Schistosoma evolution and that this duplication has been conserved.
Salter
Jason P
JP
University of California San Francisco Graduate Program in Biomedical Sciences and the Department of Pathology, University of California, San Francisco, California 94143, USA.
Choe
Youngchool
Y
Albrecht
Hugo
H
Franklin
Christopher
C
Lim
Kee-Chong
KC
Craik
Charles S
CS
McKerrow
James H
JH
D000595:Amino Acid Sequence; D000818:Animals; D017931:DNA Primers; D017238:Genes, Helminth; D007527:Isoenzymes / Q000235:genetics; D008969:Molecular Sequence Data; D010196:Pancreatic Elastase / Q000235:genetics*; D012548:Schistosoma haematobium / Q000235:genetics; D012550:Schistosoma mansoni / Q000201:enzymology* / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013379:Substrate Specificity
D017931:DNA Primers; D007527:Isoenzymes; D010196:Pancreatic Elastase