Isolation of an aspartic proteinase precursor from the egg of a hard tick, Boophilus microplus.
An aspartic proteinase precursor, herein named BYC (Boophilus Yolk pro-Cathepsin) was isolated from eggs of the hard tick, Boophilus microplus. As judged by electrophoresis on sodium dodecyl sulfate polyacrylamide slab gel (SDS-PAGE), purified BYC presented 2 bands of 54 and 49 kDa, bearing the same NH2-terminal amino acid sequence. By Western blot analysis, BYC was also found in the haemolymph, indicating an extraovarian site of synthesis. Several organs were incubated in culture medium with [35S]methionine, and only the gut and fat body showed synthesis of BYC polypeptides. Protein sequencing of both the NH2-terminal and an internal sequence obtained after cyanogen bromide (CNBr) cleavage of BYC revealed homology with several aspartic proteinase precursors. Incubation at pH 3.5 resulted in autoproteolysis of BYC, which produced the mature form of the enzyme, that displayed pepstatin-sensitive hydrolytic activity against haemoglobin. Western blot analysis using anti-BYC monoclonal antibodies showed proteolytic processing of BYC during embryogenesis and suggested activation of the enzyme during development. A role of BYC in degradation of vitellin, the major yolk protein of tick eggs, is discussed.
Logullo
C
C
Departamento de Bioquímica Médica, ICB-CCS-UFRJ, Cidade Universitária, Rio de Janeiro, RJ, Brazil. logullo@server.bioqmed.ufrj.br
Vaz
I da S
Ida S
Sorgine
M H
MH
Paiva-Silva
G O
GO
Faria
F S
FS
Zingali
R B
RB
De Lima
M F
MF
Abreu
L
L
Oliveira
E F
EF
Alves
E W
EW
Masuda
H
H
Gonzales
J C
JC
Masuda
A
A
Oliveira
P L
PL
D000273:Adipose Tissue / Q000201:enzymology; D000595:Amino Acid Sequence; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000737:chemistry / Q000302:isolation & purification*; D015153:Blotting, Western; D002848:Chromatography, DEAE-Cellulose; D004531:Eggs; D004591:Electrophoresis, Polyacrylamide Gel; D004792:Enzyme Precursors / Q000737:chemistry / Q000302:isolation & purification*; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006458:Hemolymph / Q000201:enzymology; D007422:Intestines / Q000201:enzymology; D008317:Malpighian Tubules / Q000201:enzymology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011817:Rabbits; D013987:Ticks / Q000201:enzymology* / Q000254:growth & development
D004792:Enzyme Precursors; D006454:Hemoglobins; D016282:Aspartic Acid Endopeptidases; C113293:Boophilus yolk pro-cathepsin