title: Hemoglobin digestion in blood-feeding ticks: mapping a multipeptidase pathway by functional proteomics.
abstract: Hemoglobin digestion is an essential process for blood-feeding parasites. Using chemical tools, we deconvoluted the intracellular hemoglobinolytic cascade in the tick Ixodes ricinus, a vector of Lyme disease and tick-borne encephalitis. In tick gut tissue, a network of peptidases was demonstrated through imaging with specific activity-based probes and activity profiling with peptidic substrates and inhibitors. This peptidase network is induced upon blood feeding and degrades hemoglobin at acidic pH. Selective inhibitors were applied to dissect the roles of the individual peptidases and to determine the peptidase-specific cleavage map of the hemoglobin molecule. The degradation pathway is initiated by endopeptidases of aspartic and cysteine class (cathepsin D supported by cathepsin L and legumain) and is continued by cysteine amino- and carboxy-dipeptidases (cathepsins C and B). The identified enzymes are potential targets to developing novel anti-tick vaccines.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 16610 Praha, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Horn
authors.forename: Martina
authors.initials: M
authors.lastname: Nussbaumerová
authors.forename: Miloslav
authors.initials: M
authors.lastname: Sanda
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Kovárová
authors.forename: Jindrich
authors.initials: J
authors.lastname: Srba
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Franta
authors.forename: Daniel
authors.initials: D
authors.lastname: Sojka
authors.forename: Matthew
authors.initials: M
authors.lastname: Bogyo
authors.forename: Conor R
authors.initials: CR
authors.lastname: Caffrey
authors.forename: Petr
authors.initials: P
authors.lastname: Kopácek
authors.forename: Michael
authors.initials: M
authors.lastname: Mares
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020134:Catalytic Domain; D002401:Cathepsin B / Q000378:metabolism; D020789:Cathepsin C / Q000378:metabolism; D002402:Cathepsin D / Q000378:metabolism; D056668:Cathepsin L / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006454:Hemoglobins / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D018884:Ixodes / Q000201:enzymology*; D008969:Molecular Sequence Data; D040901:Proteomics / Q000379:methods*; D000099240:Asparaginyl Endopeptidase
chemical_list: D002401:Cathepsin B; D020789:Cathepsin C; D002402:Cathepsin D; D056668:Cathepsin L; D003546:Cysteine Endopeptidases; D010450:Endopeptidases; D004791:Enzyme Inhibitors; D006454:Hemoglobins; D000099240:Asparaginyl Endopeptidase