Masler E P
Nematology Laboratory, United States Department of Agriculture, Agricultural Research Service, 10300 Baltimore Avenue, BARC-West, Beltsville, MD 20705-2350, USA.
J Helminthol. 2010 Dec;84(4):425-33. doi: 10.1017/S0022149X1000012X. Epub 2010 Mar 25.
Extracts prepared from the microbivorous nematode Panagrellus redivivus and the plant-parasitic nematode Meloidogyne incognita were used to provide general protease activities for peptide substrate screening and species comparisons. Each extract was evaluated for its ability to degrade a broad range of nematode FMRFamide-like peptides (FLPs), key regulatory messengers governing nematode growth and development. Clear quantitative differences between the two extracts were observed using FMRFamide as a substrate. Extract potency assessed at EC50 (μg/μ l extract protein for 50% substrate digestion) was 1.8-fold greater for P. redivivus than for M. incognita, and potency assessed at EC90 was 2.5-fold greater. An overall potency difference was also present when screening the digestion of 17 nematode FLPs, but it was not universal. The mean percentage digestion of eight of the 17 FLPs was greater (P < 0.02) with P. redivivus extract (76.3 ± 8.2) than with M. incognita extract (38.1 ± 8.7), but the means for the other nine FLPs were not different. Three FLPs (KPSFVRFa, AQTFVRFa, RNKFEFIRFa) were degraded extensively by the extracts of both species, and two FLPs (SAPYDPNFLRFa, SAEPFGTMRFa) were degraded 2.9-fold and 5.3-fold greater, respectively, with M. incognita extract than with P. redivivus extract. The ability of each extract to degrade FMRFa and KSAYMRFa was significantly reduced by using peptide analogues containing single d-amino acid substitutions, and the substitution effects were positional. Both FMRFa and KSAYMRFa were competitive substrates for aminopeptidases in each extract, but only the competitive ability of FMRFa was reduced by d-amino acid substitution. The variety and complexity of nematode FLP degradation by preparations representing phylogenetically and developmentally different nematode sources are discussed.
从食微生物线虫复活线虫（Panagrellus redivivus）和植物寄生线虫南方根结线虫（Meloidogyne incognita）中制备的提取物，用于提供一般蛋白酶活性，以进行肽底物筛选和物种比较。评估了每种提取物降解多种线虫FMRF酰胺样肽（FLP）的能力，这些肽是控制线虫生长和发育的关键调节信使。以FMRF酰胺为底物时，观察到两种提取物之间存在明显的定量差异。以EC50（50%底物消化所需的μg/μl提取物蛋白）评估的提取物效力，复活线虫比南方根结线虫高1.8倍，以EC90评估的效力高2.5倍。在筛选17种线虫FLP的消化情况时，也存在总体效力差异，但并非普遍存在。17种FLP中的8种，复活线虫提取物的平均消化百分比（76.3±8.2）高于南方根结线虫提取物（38.1±8.7）（P<0.02），但其他9种FLP的平均值没有差异。三种FLP（KPSFVRFa、AQTFVRFa、RNKFEFIRFa）被两种线虫的提取物广泛降解，两种FLP（SAPYDPNFLRFa、SAEPFGTMRFa）被南方根结线虫提取物降解的程度分别比复活线虫提取物高2.9倍和5.3倍。使用含有单个d-氨基酸取代的肽类似物时，每种提取物降解FMRFa和KSAYMRFa的能力显著降低，且取代效应具有位置特异性。FMRFa和KSAYMRFa都是每种提取物中氨肽酶的竞争性底物，但只有FMRFa的竞争能力因d-氨基酸取代而降低。讨论了来自系统发育和发育不同线虫来源的制剂对线虫FLP降解的多样性和复杂性。
