Nonproteolytic serine proteinase homologs are involved in prophenoloxidase activation in the tobacco hornworm, Manduca sexta

Yu, Xiao‐Qiang; Jiang, Haobo; Wang, Yang; Kanost, Michael R.

doi:10.1016/s0965-1748(02)00191-1

Cited by 215 publications

(249 citation statements)

References 39 publications

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“…Hence, our data suggest that we have precipitated a complex of these proteins. This is consistent with the suggestion of Yu et al (29) that, in M. sexta, Immunolectin-2 (a C-type lectin), after binding to surface polysaccharides of microbes, forms a complex together with serine-proteinase homologs and proPO-activating factors. Our results on the dietary induction of Glucanase-1 by bacteria as well as by LTA and LPS correlate well with observations of one of its orthologs in the mosquito A. gambiae, GNBP-B1, for which the expression is induced upon bacterial challenge with both Gram-negative and Gram-positive bacteria with a stronger effect observed with the latter (30).…”

Section: Discussionsupporting

confidence: 93%

Immunity or Digestion

Pauchet

Freitak²,

Heidel‐Fischer

et al. 2009

Journal of Biological Chemistry

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The cell surfaces of microorganisms display distinct molecular patterns formed from lipopolysaccharides, peptidoglycans, or ␤1,3-glucans. Binding of these surfaces by pattern recognition proteins such as ␤1,3-glucan recognition proteins (␤GRPs) activates the immune response in arthropods. We identified a 40-kDa ␤1,3-glucan-binding protein with sequence similarity to previously characterized lepidopteran ␤GRPs from hemolymph, but unlike these it is secreted into the larval gut lumen and is an active ␤1,3-glucanase. This glucanase was not detected in hemolymph. Its mRNA is constitutively and predominantly expressed in the midgut and is induced there when larvae feed on a diet containing bacteria. Homologs of this predominantly midgut-expressed gene from many Lepidoptera possess key residues shown to be part of the active site of other glucanases, and form a cluster that is distinct from previously described ␤GRPs. In addition, this group includes proteins from insects such as the Anopheles gambiae GNBP subgroup B for which a catalytic role has not been previously suspected. The current domain classification does not distinguish between the catalytic and noncatalytic clades, and should be revised. The noncatalytic ␤GRPs may be evolutionarily derived from this newly described enzyme family that continues to function catalytically in digestion and/or pathogen defense.

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Section: Discussionsupporting

confidence: 93%

Immunity or Digestion

Pauchet

Freitak²,

Heidel‐Fischer

et al. 2009

Journal of Biological Chemistry

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“…This has led to the identification of PRRs in B. mori and several other species that activate the PO cascade when they bind microbial cell wall components (33)(34)(35). Studies in this area have also shed important light on the function of SPHs as PAP cofactors (47,48) and as proteins that bind to PO and microbial cell wall components to form complexes that localize melanin deposition to the surface of bacteria (27,28,38,40).…”

Section: Discussionmentioning

confidence: 99%

Hemolymph Melanization in the Silkmoth Bombyx mori Involves Formation of a High Molecular Mass Complex That Metabolizes Tyrosine

Clark

Strand

2013

Journal of Biological Chemistry

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Background:The phenoloxidase (PO) cascade regulates the melanization of blood in insects and other arthropods. Results: Hemolymph from Bombyx mori rapidly melanizes after wounding and forms a complex that uses tyrosine as the substrate. Conclusion: Tyrosine usage requires formation of a phenoloxidase-containing complex. Significance: Processing of prophenoloxidase is an intermediate step in the phenoloxidase cascade.

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“…Like PAP-2, M. sexta PAP-1 or PAP-3 also activates proPO in the presence of SPH-1 and SPH-2 (Yu et al, 2003). While HP21 converts proPAP-3 to PAP-3 (Gorman et al, 2007), it is unclear how proPAP-1 becomes active: preliminary data did not support HP21 as a universal activator of the proPAPs.…”

Section: Discussionmentioning

confidence: 99%

“…The enzyme, through sequentially activated serine proteinases, eventually yields a specific proteinase to cleave proPO. At least in some insects, proPO activating proteinases (PAPs) require one or two non-catalytic serine proteinase homologs (SPHs) as a "cofactor" to generate active PO (Jiang et al, 1998;Lee et al, 1998;Kwon et al, 2000;Yu et al, 2003). Like PAPs, SPHs need cleavage activation by a serine proteinase in the cascade (Kim et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Reconstitution of a branch of the Manduca sexta prophenoloxidase activation cascade in vitro: Snake-like hemolymph proteinase 21 (HP21) cleaved by HP14 activates prophenoloxidase-activating proteinase-2 precursor

Wang¹,

Jiang²

2007

Insect Biochemistry and Molecular Biology

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Upon wounding or infection, a serine proteinase cascade in insect hemolymph leads to prophenoloxidase (proPO) activation and melanization, a defense response against invading microbes. In the tobacco hornworm Manduca sexta, this response is initiated via hemolymph proteinase 14 (HP14), a mosaic protein that interacts with bacterial peptidoglycan or fungal β-1,3-glucan to autoactivate. In this paper, we report the expression, purification, and functional analysis of M. sexta HP21 precursor, an HP14 substrate similar to Drosophila Snake. The recombinant proHP21 is a 51.1 kDa glycoprotein with an amino-terminal clip domain, a linker region, and a carboxyl-terminal serine proteinase domain. HP14, generated by incubating proHP14 with β-1,3-glucan and β-1,3-glucan recognition protein-2, activated proHP21 by limited proteolysis between Leu 152 and Ile 153 . Active HP21 formed an SDS-stable complex with M. sexta serpin-4, a physiological regulator of the proPO activation system. We determined the P1 site of serpin-4 to be Arg 355 and, thus, confirmed our prediction that HP21 has trypsin-like specificity. After active HP21 was added to the plasma, there was a major increase in PO activity. HP21 cleaved proPO activating proteinase-2 precursor (proPAP-2) after Lys 153 and generated an amidase activity which activated proPO in the presence of serine proteinase homolog-1 and 2. In summary, we have discovered and reconstituted a branch of the proPO activation cascade in vitro: β-1,3-glucan recognition -proHP14 autoactivation -proHP21 cleavage -PAP-2 generation -proPO activation -melanin formation.

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Nonproteolytic serine proteinase homologs are involved in prophenoloxidase activation in the tobacco hornworm, Manduca sexta

Cited by 215 publications

References 39 publications

Immunity or Digestion

Immunity or Digestion

Hemolymph Melanization in the Silkmoth Bombyx mori Involves Formation of a High Molecular Mass Complex That Metabolizes Tyrosine

Reconstitution of a branch of the Manduca sexta prophenoloxidase activation cascade in vitro: Snake-like hemolymph proteinase 21 (HP21) cleaved by HP14 activates prophenoloxidase-activating proteinase-2 precursor

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