In:
Biochemical Journal, Portland Press Ltd., Vol. 388, No. 1 ( 2005-05-15), p. 281-289
Abstract:
In the last decade, a new serine protease inhibitor family has been described in arthropods. Eight members of the family were purified from locusts and share a conserved cysteine array (Cys-Xaa9–12-Cys-Asn-Xaa-Cys-Xaa-Cys-Xaa2–3-Gly-Xaa3–6-Cys-Thr-Xaa3-Cys) with nine inhibitory domains of the light chain of the crayfish protease inhibitor, pacifastin (PLDs; pacifastin light chain domains). Using cDNA cloning, several pacifastin-related precursors have been identified, encoding additional PLD-related peptides in different insect species. In the present study, two isoforms of a novel pacifastin-related precursor (SGPP-4) have been identified in the desert locust, predicting the previously identified SGPI-5 (Schistocerca gregaria PLD-related inhibitor-5) peptide and two novel PLD-related peptide sequences. One novel peptide (SGPI-5A) was synthesized chemically, and its inhibitory activity was assessed in vitro. Although proteases from a locust midgut extract were very sensitive to SGPI-5A, the same peptide proved to be a relatively poor inhibitor of bovine trypsin. By an in silico datamining approach, a novel pacifastin-related precursor with seven PLD-related domains was identified in the mosquito, Aedes aegypti. As in other insect pacifastin-related precursors, the Aedes precursor showed a particular domain architecture that is not encountered in other serine protease inhibitor families. Finally, a comparative real-time RT-PCR analysis of SGPP-4 transcripts in different tissues of isolated- (solitarious) and crowded-reared (gregarious) locusts was performed. This showed that SGPP-4 mRNA levels are higher in the brain, testes and fat body of gregarious males than of solitarious males. These results have been compared with data from a similar study on SGPP-1–3 transcripts and discussed with respect to a differential regulation of serine-protease-dependent pathways as a possible mechanism underlying locust phase polymorphism.
Type of Medium:
Online Resource
ISSN:
0264-6021
,
1470-8728
Language:
English
Publisher:
Portland Press Ltd.
Publication Date:
2005
detail.hit.zdb_id:
1473095-9
SSG:
12
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