Enhancin, the Granulosis Virus Protein That Facilitates Nucleopolyhedrovirus (NPV) Infections, Is a Metalloprotease

Lepore, Leslie S.; Roelvink, Peter W.; Granados, Robert R.

doi:10.1006/jipa.1996.0070

Cited by 138 publications

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“…The proteinase may directly harm the larvae, or it may catalyze the production of a toxic molecule from a substrate present in either the plant or insect. Or perhaps it may act like "enhancin," a Tricoplusia ni granulovirus protein (Lepore et al, 1996). This metalloproteinase degrades proteins in the peritropic membrane of the insect, and the increased permeability of this membrane enhances the susceptibility of the larvae to nucleopolyhedrovirus.…”

Section: Discussionmentioning

confidence: 99%

A Unique 33-kD Cysteine Proteinase Accumulates in Response to Larval Feeding in Maize Genotypes Resistant to Fall Armyworm and Other Lepidoptera

et al. 2000

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Plants respond to insect feeding with a number of defense mechanisms. Using maize genotypes derived from Antiquan germ plasm that are resistant to Lepidoptera, we have demonstrated that a unique 33-kD cysteine proteinase accumulates in the whorl in response to larval feeding. The abundance of the proteinase increased dramatically at the site of larval feeding after 1 hr of infestation and continued to accumulate for as long as 7 days. The 33-kD cysteine proteinase was most abundant in the yellow-green portion of the whorl-the normal site of larval feeding and the tissue that has the greatest inhibitory effect on larval growth in bioassays. The proteinase was expressed in response to wounding and was found in senescent leaves. It may be a marker of programmed cell death. The gene coding for the proteinase, mir1 , has been transformed into Black Mexican Sweet callus. When larvae were reared on callus expressing the proteinase, their growth was inhibited ‫ف‬ 60 to 80%. The expression of a cysteine proteinase, instead of a cysteine proteinase inhibitor, may be a novel insect defense mechanism in plants. INTRODUCTIONOver the past 25 years, maize inbreds resistant to feeding by larvae of numerous lepidopteran species have been developed from Antiguan germ plasm (Williams and Davis, 1982;Williams et al., 1990a). Inbreds derived from this germ plasm (Mp704 and Mp708) are resistant to feeding by fall armyworm ( Spodoptera frugiperda ), southwestern corn borer ( Diatraea grandiosella), European corn borer ( Ostinia nubilalis ), sugarcane borer ( D. saccharalis), tobacco budworm ( Heliothis virescens ), corn earworm ( Helicoverpa zea ), and other Lepidoptera. Fall armyworm larvae feed extensively on whorl leaf tissue, often resulting in crop losses. Genetic and quantitative trait loci analyses indicate that resistance to these Lepidoptera is a quantitative trait regulated by several genes (Williams et al., 1989;Khairallah et al., 1998). Traits such as high hemicellulose content, low protein content, and leaf toughness appear to be correlated with reduced larval growth (Williams et al., 1998). No studies have indicated conclusively that secondary products contribute to the resistance, but two-dimensional gel electrophoresis has indicated that the presence of 36-and 21-kD proteins in the whorl may be predictive of resistance (Callahan et al., 1992).Bioassays in which fall armyworm larvae are reared on lyophilized whorl tissues indicate that larvae reared on resistant material weigh ‫ف‬ 50% less than those reared on susceptible material (Williams et al., 1990b). Larvae reared on lyophilized whorl tissue from resistant genotypes are smaller, grow more slowly, and pupate later than those reared on similar material from susceptible genotypes (Chang et al., 2000). The major effect of this germplasm is to slow larval growth and development and to increase the amount of time larvae are vulnerable to predators and parasites.The same phenotype, a 50% reduction in larval growth, is apparent when larvae are reared on nonfriable callus ...

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Section: Discussionmentioning

confidence: 99%

A Unique 33-kD Cysteine Proteinase Accumulates in Response to Larval Feeding in Maize Genotypes Resistant to Fall Armyworm and Other Lepidoptera

et al. 2000

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“…Movement through the peritrophic membrane is thought to be facilitated by metalloproteinases termed enhancins (Slavicek, this volume). Enhancins are located within the ODV membrane in the LdMNPV (Slavicek & Popham, 2005) or are co-occluded in the granule of granuloviruses (Wang et al, 1994;Lepore et al, 1996). However, most baculoviruses lack enhancin genes; consequently other means that have yet to be elucidated are used to traverse the peritrophic membrane.…”

Section: Penetration Of the Peritrophic Membranementioning

confidence: 99%

Interactions Between Nucleopolyhedroviruses and Polydnaviruses in Larval Lepidoptera

D’Amico¹,

Slavicek²

2012

Molecular Virology

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“…In the case of Trichoplusia ni granulovirus (TnGV), this enhancement of NPV infectivity was linked to degradation of the host insect PM and increased PM permeability caused by a metalloprotease, enhancin, that was associated with the OBs (Lepore et al, 1996;Peng et al, 1999). Virus-enhancing activity of purified enhancin has been well-documented in betabaculoviruses (Gallo et al, 1991;Wang et al, 1994;Wang & Granados, 1998).…”

Section: Introductionmentioning

confidence: 99%

Role of enhancin in Mamestra configurata nucleopolyhedrovirus virulence: selective degradation of host peritrophic matrix proteins

Toprak

Harris

Baldwin

et al. 2012

Journal of General Virology

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To infect per os, baculovirus virions cross the peritrophic matrix (PM) to reach the midgut epithelium. Insect intestinal mucins (IIMs) are PM proteins that protect the PM and aid passage of the food bolus through the gut. Some baculoviruses, including Mamestra configurata nucleopolyhedrovirus (MacoNPV-A), encode metalloproteases, known as enhancins, that facilitate infection by degrading IIMs. We examined the interaction between MacoNPV-A enhancin and M. configurata IIMs both in vivo and in vitro. Per os inoculation of M. configurata larvae with MacoNPV-A occlusion bodies (OBs) resulted in the degradation of McIIM4 within 4 h of OB ingestion, while McIIM2 was unaffected. The PM recovered by 8 h post-inoculation. To investigate whether enhancin was responsible for the degradation of IIM, a recombinant Autographa californica multiple nucleopolyhedrovirus expressing MacoNPV enhancin (AcMNPVenMP2) was constructed. Enhancin was found to be a component of occlusion-derived virions in AcMNPV-enMP2 and MacoNPV-A. In in vitro assays, McIIM4 was degraded after MacoNPV-A and AcMNPV-enMP2 treatments. Degradation of McIIM4 was inhibited by EDTA, a metalloprotease inhibitor, indicating that the degradation was due to enhancin activity. Thus, MacoNPV-A enhancin is able to degrade major structural PM proteins, but exhibits target substrate specificity. INTRODUCTIONThe family Baculoviridae includes arthropod-specific viruses with large, circular, covalently closed, dsDNA genomes of between 80 and 180 kbp. The family includes four genera: Alphabaculovirus [formerly known as Nucleopolyhedrovirus (NPV)], members of which infect lepidopteran hosts; Betabaculovirus [Granulovirus (GV)]; Gammabaculovirus (hymenopteran-specific NPV); and Deltabaculovirus (dipteran-specific NPV) (Jehle et al., 2006). Baculoviruses have two virion phenotypes, budded virus (BV) and occlusionderived virus (ODV). BVs are formed early in the infection cycle when nucleocapsids bud through the host-cell membrane and acquire an envelope. The BVs are responsible for cell-to-cell transmission of the virus within the host insect. Late in the infection cycle, nucleocapsids are enveloped (single or multiple nucleocapsids per virion) by membranes formed within the infected host-cell nucleus and these virions are subsequently occluded within proteinaceous crystals or occlusion bodies (OBs). These ODVs are infectious to insect midgut cells upon ingestion by a susceptible host.In order for baculovirus ODVs to infect insect midgut cells, they must first cross the peritrophic matrix (PM), a semipermeable sheath that is composed of chitin microfibrils and proteins, lining the midgut of most insect species (Wang & Granados, 1997a). The PM protects the midgut epithelium from mechanical damage, toxic compounds and pathogens, regulates nutrient uptake by compartmentalizing digestive processes and prevents excretion of digestive enzymes by providing a means for enzyme recycling (reviewed by Hegedus et al., 2009). The protective feature of the PM is in part due to insect intesti...

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Enhancin, the Granulosis Virus Protein That Facilitates Nucleopolyhedrovirus (NPV) Infections, Is a Metalloprotease

Cited by 138 publications

References 0 publications

A Unique 33-kD Cysteine Proteinase Accumulates in Response to Larval Feeding in Maize Genotypes Resistant to Fall Armyworm and Other Lepidoptera

A Unique 33-kD Cysteine Proteinase Accumulates in Response to Larval Feeding in Maize Genotypes Resistant to Fall Armyworm and Other Lepidoptera

Interactions Between Nucleopolyhedroviruses and Polydnaviruses in Larval Lepidoptera

Role of enhancin in Mamestra configurata nucleopolyhedrovirus virulence: selective degradation of host peritrophic matrix proteins

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