Isolation of an aspartic proteinase precursor from the egg 
of a hard tick, <i>Boophilus microplus</i>

Logullo, Carlos; Vaz, Itabajara da Silva; Sorgine, Marcos Henrique Ferreira; Paiva-Silva, Gabriela O.; Faria, Fernanda; Zingali, Russolina B.; Lima, Monica Fernandes Rosa de; Abreu, Leonardo; Oliveira, Leandro De; Alves, Elias W.; Masuda, Hatisaburo; Gonzales, João Carlos; Masuda, Aoi; Oliveira, Pedro L.

doi:10.1017/s0031182098002698

Cited by 76 publications

(64 citation statements)

References 21 publications

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“…A previous report has shown that acidification, and the consequent activation of an acid aspartic proteinase, is required for yolk degradation in the cattle tick Boophilus microplus (Logullo et al 1998). In this work we report the presence of a (cathepsin L-like) cysteine endopeptidase, which is associated with vitellin, in eggs of B. microplus and that probably has a role in the VT degradation during B. microplus embryogenesis.…”

Section: Introductionsupporting

confidence: 53%

“…Ticks fed on BYCvaccinated bovines presented functional bovine immunoglobulins circulating in haemolymph (Da Silva Vaz Jr et al 1996). Moreover, cattle vaccinated with BYC presented a partially protective immune response against B. microplus infestation, mainly due to a decreased number of fertile eggs (Da Silva Vaz Jr et al 1998). Considering that VT degradation results from the activity of both enzymes (BYC and VTDCE), VT degradation would be even more impaired if, in addition to antibodies against BYC, bovine antibodies against VTDCE could also be raised.…”

Section: Discussionmentioning

confidence: 99%

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A Boophilus microplus vitellin-degrading cysteine endopeptidase

et al. 2003

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Here we describe the purification and characterization of a vitellin (VT) degrading cysteine endopeptidase (VTDCE) from eggs of the hard tick Boophilus microplus. A homogeneous enzyme preparation was obtained by chromatographic fractionation on ion-exchange and gel filtration columns and an autolysis step. This step consisted of incubation of a semipurified enzyme (after the first ion-exchange chromatography) at pH 4 . 0 that dissociated the enzyme from VT, to which VTDCE is naturally tightly associated. The enzyme purity was confirmed by capillary and native gel electrophoresis, and SDS-PAGE suggested the enzyme is a dimer of 17 and 22 kDa. VTDCE was active upon several synthetic substrates, with a preference for a hydrophobic or a basic residue in P 1 , and a hydrophobic residue in P 2 . VTDCE also hydrolysed haemoglobin, albumin, gelatin and vitellin. VTDCE is inactive in the absence of DTT and was totally inhibited by E-64, indicating it is a cysteine endopeptidase. Our results suggest that VTDCE is a major enzyme involved in yolk processing during B. microplus embryogenesis.

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Section: Introductionsupporting

confidence: 53%

Section: Discussionmentioning

confidence: 99%

A Boophilus microplus vitellin-degrading cysteine endopeptidase

et al. 2003

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“…Newly laid eggs are therefore able to initiate VT degradation. In vitro, measurements of hydrolase activities and yolk degradation using fresh eggs have been investigated by many groups (Nussenzveig et al, 1992;Logullo et al, 1998;Sorgine et al, 2000;Fialho et al, 2002). However, even though freshly laid eggs carry all the yolk mobilization machinery, the massive yolk proteolysis does not occur in vivo immediately after the egg is laid, but starts at a certain time later, during early embryogenesis.…”

Section: Discussionmentioning

confidence: 99%

Calcium-regulated fusion of yolk granules is important for yolk degradation during early embryogenesis of Rhodnius prolixusStahl

Ramos

Miranda

Souza

et al. 2007

Journal of Experimental Biology

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SUMMARY This study examined the process of membrane fusion of yolk granules (YGs)during early embryogenesis of Rhodnius prolixus. We show that eggs collected at days 0 and 3 after oviposition contain different populations of YGs, for example day-3 eggs are enriched in large YGs (LYGs). Day-3 eggs also contain the highest free [Ca2+] during early embryogenesis of this insect. In vitro incubations of day-0 YGs with [Ca2+]similar to those found in day-3 eggs resulted in the formation of LYGs, as observed in vivo. Fractionation of LYGs and small YGs (SYGs) and their subsequent incubation with the fluorescent membrane marker PKH67 showed a calcium-dependent transference of fluorescence from SYGs to LYGs, possibly as the result of membrane fusion. Acid phosphatase and H+-PPase activities were remarkably increased in day-3 LYGs and in calcium-treated day-0 LYGs. Both fractions were found to contain vitellins as major components, and incubation of YGs with calcium induced yolk proteolysis in vitro. Altogether, our results suggest that calcium-induced membrane fusion events take part in yolk degradation, leading to the assembly of the yolk mobilization machinery.

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“…3C and 4). We previously described another aspartic proteinase, also isolated from Boophilus eggs, called BYC (10). However, none of BYC sequences were identified in THAP cDNA, confirming that BYC and THAP are in fact different proteins.…”

Section: N-cbz-fr-mca (24) Nd N-t-boc-grr-mca (24)mentioning

confidence: 97%

A Heme-binding Aspartic Proteinase from the Eggs of the Hard TickBoophilus microplus

Sorgine

Logullo

Zingali

et al. 2000

Journal of Biological Chemistry

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An aspartic proteinase that binds heme with a 1:1 stoichiometry was isolated and cloned from the eggs of the cattle tick Boophilus microplus. This proteinase, herein named THAP (tick heme-binding aspartic proteinase) showed pepstatin-sensitive hydrolytic activity against several peptide and protein substrates. Although hemoglobin was a good substrate for THAP, low proteolytic activity was observed against globin devoid of the heme prosthetic group. Hydrolysis of globin by THAP increased as increasing amounts of heme were added to globin, with maximum activation at a heme-toglobin 1:1 ratio. Further additions of heme to the reaction medium inhibited proteolysis, back to a level similar to that observed against globin alone. The addition of heme did not change THAP activity toward a synthetic peptide or against ribonuclease, a non-hemeprotein substrate. The major storage protein of tick eggs, vitellin (VT), the probable physiological substrate of THAP, is a hemeprotein. Hydrolysis of VT by THAP was also inhibited by the addition of heme to the incubation media. Taken together, our results suggest that THAP uses heme bound to VT as a docking site to increase specificity and regulate VT degradation according to heme availability.

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Isolation of an aspartic proteinase precursor from the egg of a hard tick, Boophilus microplus

Cited by 76 publications

References 21 publications

A Boophilus microplus vitellin-degrading cysteine endopeptidase

A Boophilus microplus vitellin-degrading cysteine endopeptidase

Calcium-regulated fusion of yolk granules is important for yolk degradation during early embryogenesis of Rhodnius prolixusStahl

A Heme-binding Aspartic Proteinase from the Eggs of the Hard TickBoophilus microplus

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