Sp22D: a multidomain serine protease with a putative role in insect immunity

Gorman, Maureen J.; Andreeva, O. V.; Paskewitz, Susan M.

doi:10.1016/s0378-1119(00)00181-5

Cited by 53 publications

(27 citation statements)

References 27 publications

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“…42 Pathogen infections can activate a lot of immune factors expressed in mosquito fat body. [43][44][45][46][47][48][49] Therefore, immune response may play an important role in the process of DENV infection in mosquito fat body. Our results indicated that DENV-2 infection in fat body may induce rapid immune response at early times post-infection that can suppress virus replication in low level and protect fat body and even other organs from damage.…”

Section: Discussionmentioning

confidence: 99%

Quantitative Analysis of Replication and Tropisms of Dengue Virus Type 2 in Aedes albopictus

Zhang

Zheng²,

Yu³

et al. 2010

The American Society of Tropical Medicine and Hygiene

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Dengue virus serotype 2 (DENV-2) RNA replication profiles and tropisms were studied by using quantitative RT-PCR (q-RTPCR) in intrathoracically infected Aedes albopictus. The virus RNA replication profiles were diverse in mosquito organs. In fat body, brain, salivary gland, and malpighian tubes, it peaked at 8, 23, 23, and 27 days post-infection, respectively, and then, all declined. In midgut, it increased all the time and had no trend of decline. In ovary, it had no apparent increase. Subsequent Western blotting of DENV-2 E protein had similar results. Using ribosomal protein 7 (rpS7) as an internal control, we found that, in salivary gland, brain, fat body, and midgut, the average DENV-2 RNA levels (DENV-2 RNA/rpS7 mRNA) were 1,028, 464, 5.6, and 6.2, respectively; in malpighian tubes, it was 1, and in ovary, it was far less than 1. These results suggest that infection profiles and tropism of DENV-2 RNA in Ae. albopictus organs are significantly different.

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Section: Discussionmentioning

confidence: 99%

Quantitative Analysis of Replication and Tropisms of Dengue Virus Type 2 in Aedes albopictus

Zhang

Zheng²,

Yu³

et al. 2010

The American Society of Tropical Medicine and Hygiene

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“…The ChtBD of AprIV is 57 amino acid residues long and exhibits homology with ChtBDs classified into type 3. Sequence align- (8). It was proposed that Sp22D might serve as sentinel to detect exposed chitin and then trigger appropriate physiological or developmental responses based on domain organization (5).…”

Section: Discussionmentioning

confidence: 99%

Molecular Analysis of the Gene Encoding a Novel Chitin-Binding Protease fromAlteromonassp. Strain O-7 and Its Role in the Chitinolytic System

et al. 2002

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Alteromonas sp. strain O-7 secretes several proteins in response to chitin induction. We have found that one of these proteins, designated AprIV, is a novel chitin-binding protease involved in chitinolytic activity. The gene encoding AprIV (aprIV) was cloned in Escherichia coli. DNA sequencing analysis revealed that the open reading frame of aprIV encoded a protein of 547 amino acids with a calculated molecular mass of 57,104 Da. AprIV is a modular enzyme consisting of five domains: the signal sequence, the N-terminal proregion, the family A subtilase region, the polycystic kidney disease domain (PkdD), and the chitin-binding domain type 3 (ChtBD3). Expression plasmids coding for PkdD or both PkdD and ChtBD (PkdD-ChtBD) were constructed. The PkdD-ChtBD but not PkdD exhibited strong binding to α-chitin and β-chitin. Western and Northern analyses demonstrated that aprIV was induced in the presence of N-acetylglucosamine, N-acetylchitobiose, or chitin. Native AprIV was purified to homogeneity from Alteromonas sp. strain O-7 and characterized. The molecular mass of mature AprIV was estimated to be 44 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The optimum pH and temperature of AprIV were pH 11.5 and 35°C, respectively, and even at 10°C the enzyme showed 25% of the maximum activity. Pretreatment of native chitin with AprIV significantly promoted chitinase activity

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“…So far, little is understood regarding parasite recognition or initiation of proPO activation in mosquitoes. Sp22D, a modular serine proteinase in A. gambiae, contains two chitin-binding domains, a mucin-like region, two LDLr class A repeats, and two scavenger receptor cysteine-rich domains (32,33). Whereas some of these domains are thought to be important for pathogen recognition, Sp22D does not bind to bacteria.…”

Section: Figmentioning

confidence: 99%

A Pattern Recognition Serine Proteinase Triggers the Prophenoloxidase Activation Cascade in the Tobacco Hornworm, Manduca sexta

Wang

Guo

et al. 2004

Journal of Biological Chemistry

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A serine proteinase cascade in insect hemolymph mediates prophenoloxidase activation, a defense mechanism against pathogen or parasite infection. Little is known regarding its initiating proteinase or how this enzyme is activated in response to invading microorganisms. We have isolated from the tobacco hornworm, Manduca sexta, a cDNA encoding a modular protein designated hemolymph proteinase 14 (HP14). It contains five low density lipoprotein receptor class A repeats, a Sushi domain, a unique Cys-rich region, and a proteinase-catalytic domain. The HP14 mRNA exists in fat body and hemocytes of the naive larvae, and its level increases significantly at 24 h after a bacterial challenge. We expressed proHP14 with a carboxyl-terminal hexahistidine tag in a baculovirus/insect cell system and detected the recombinant protein in two forms. The 87-kDa protein was primarily intracellular, whereas the 75-kDa form was present in the medium. Interaction with peptidoglycan resulted in proteolytic processing of the purified zymogen and generation of an amidase activity. Supplementation of hemolymph with proHP14 greatly enhanced prophenoloxidase activation in response to Micrococcus luteus. These data suggest that proHP14 is a pattern recognition protein that binds to bacteria and autoactivates and triggers the prophenoloxidase activation system in the hemolymph of M. sexta.Similar to other invertebrates, insects lack an adaptive immune system and rely solely on their innate immune mechanisms to fight against invading microorganisms (1-3). These defense mechanisms are mediated by hemocytes (e.g. phagocytosis and encapsulation), fat body (e.g. induced synthesis of antimicrobial peptides), and plasma factors (e.g. hemolymph coagulation and melanization). Accumulating evidence indicates that a complex serine proteinase network in insect hemolymph coordinates some of these responses (4). The prophenoloxidase (proPO) 1 activation cascade is probably composed of several serine proteinases that are sequentially activated in response to microbial infection and lead to the proteolytic activation of proPO to phenoloxidase (PO). PO catalyzes the formation of quinones that are reactive intermediates for melanin synthesis (5, 6). Quinones are also involved in cuticle sclerotization, wound healing, and sequestration of parasites or pathogens.Although the physiological importance of the proPO activation in insect immune system has been appreciated for many years, the molecular characterization of the cascade components was reported only recently. We isolated three proPOactivating proteinases from cuticular extract or hemolymph of M. sexta prepupae, and they all required a protein cofactor for proPO activation (7-10). Similar results were obtained from the beetles Holotrichia diomphalia and Tenebrio molitor (11-13). In contrast, the silkworm proPO-activating enzyme does not appear to need any auxiliary factor for proPO activation (14). Limited by substrate availability, current biochemical research is focused on the components at the end of th...

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Sp22D: a multidomain serine protease with a putative role in insect immunity

Cited by 53 publications

References 27 publications

Quantitative Analysis of Replication and Tropisms of Dengue Virus Type 2 in Aedes albopictus

Quantitative Analysis of Replication and Tropisms of Dengue Virus Type 2 in Aedes albopictus

Molecular Analysis of the Gene Encoding a Novel Chitin-Binding Protease fromAlteromonassp. Strain O-7 and Its Role in the Chitinolytic System

A Pattern Recognition Serine Proteinase Triggers the Prophenoloxidase Activation Cascade in the Tobacco Hornworm, Manduca sexta

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