Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000, Ljubljana, Slovenia.
J Comp Physiol B. 2010 Nov;180(8):1143-53. doi: 10.1007/s00360-010-0485-7. Epub 2010 Jun 11.
Because endogenous cellulases have been observed in arthropods, the potential ability to produce cellulose degrading enzymes was examined in the terrestrial isopod Porcellio scaber, an important decomposer of decayed plant material. cDNA fragments encoding portions of two novel endo-β-1,4-glucanase amino acid sequences were amplified by RT-PCR, and the amino acid sequences predicted were affiliated to endo-β-1,4-glucanases from other arthropods, where they cluster with endo-β-1,4-glucanases of decapod crustaceans. Hybridization in situ reveals the hepatopancreas to be the primary site of gene expression and provides direct evidence of the endogenous origin of endo-β-1,4-glucanase in P. scaber. Conservation of catalytically important amino acid residues suggests that both sequences translate into functional cellulases. Cellulolytic activity was detected in hepatopancreatic extract after separation by SDS-PAGE, which included CMC as substrate. This is the first evidence of endogenous cellulases in peracarid crustaceans and gives strong support for the involvement of isopod endo-β-1,4-glucanases in the degradation of cellulose in their diet.
由于在节肢动物中观察到了内源性纤维素酶，因此研究了陆地等足目 Porcellio scaber 产生纤维素降解酶的潜在能力，Porcellio scaber 是腐烂植物物质的重要分解者。通过 RT-PCR 扩增了编码两个新型内切-β-1,4-葡聚糖酶氨基酸序列部分的 cDNA 片段，预测的氨基酸序列与其他节肢动物的内切-β-1,4-葡聚糖酶有关，它们与十足目甲壳动物的内切-β-1,4-葡聚糖酶聚类。原位杂交表明，肝胰腺是基因表达的主要部位，并为 P. scaber 中内源性内切-β-1,4-葡聚糖酶的来源提供了直接证据。催化重要氨基酸残基的保守性表明，这两个序列都翻译成具有功能的纤维素酶。在 SDS-PAGE 分离后，在肝胰腺提取物中检测到了纤维素酶活性，其中包括 CMC 作为底物。这是首次在甲壳纲等足目动物中发现内源性纤维素酶的证据，有力地支持了等足目动物的内切-β-1,4-葡聚糖酶参与其饮食中纤维素的降解。
