title: Cloning and characterization of trypsin- and chymotrypsin-like proteases from the midgut of the sand fly vector Phlebotomus papatasi.
abstract: Trypsin and chymotrypsin serine proteases are the main digestive proteases in Diptera midguts and are also involved in many aspects of the vector-parasite relationship. In sand flies, these proteases have been shown to be a potential barrier to Leishmania growth and development within the midgut. Here we describe the sequence and partial characterization of six Phlebotomus papatasi midgut serine proteases: two chymotrypsin-like (Ppchym1 and Ppchym2) and four trypsin-like (Pptryp1-Pptryp4). All six enzymes show structural features typical to each type, including the histidine, aspartic acid, and serine (H/D/S) catalytic triad, six conserved cysteine residues, and other amino acid residues involved in substrate specificity. They also show a high degree of homology (40-60% identical residues) with their counterparts from other insect vectors, such as Anopheles gambiae and Aedes aegypti. The mRNA expression profiles of these six proteases vary considerably: two trypsin-like proteases (Pptryp1 and Pptryp2) are downregulated and one (Pptryp4) upregulated upon blood feeding. The two chymotrypsin-like enzymes display expression behavior similar to that of the early and late trypsins from Ae. aegypti.
authors.affiliation: Intracellular Parasite Biology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, 4 Center Drive, Building 4, Room 126, MSC-0425, NIH, Bethesda, MD 20892-0425, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Ramalho-Ortigão
authors.forename: S
authors.initials: S
authors.lastname: Kamhawi
authors.forename: E D
authors.initials: ED
authors.lastname: Rowton
authors.forename: J M C
authors.initials: JM
authors.lastname: Ribeiro
authors.forename: J G
authors.initials: JG
authors.lastname: Valenzuela
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002918:Chymotrypsin / Q000235:genetics*; D017931:DNA Primers; D004064:Digestive System / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic; D008969:Molecular Sequence Data; D010691:Phlebotomus / Q000145:classification / Q000201:enzymology*; D010802:Phylogeny; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000235:genetics*; D014357:Trypsin / Q000235:genetics*
chemical_list: D000596:Amino Acids; D017931:DNA Primers; D012697:Serine Endopeptidases; D002918:Chymotrypsin; D014357:Trypsin