. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. the T. vaginalis Fe-hydrogenase was greater than that of the recombinant entamoebic GST-entamoebic Fe-hydrogenase and was inhibited by a lysate of non-transfected entamoebas (Table 1). This may explain why it was difficult to detect Fe-hydrogenase activity in lysates of nontransfected ent- amoebas, even though Fe-hydrogenase 1 mRNAs were identified from them by RT-PCR (next section). Cultured entamoehas and giurdiiifi exprexx mRNAs en- coding short Fe-hydrogenases. We isolated an fe-hydroge- nase gene of G. lanihlia. because
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. the T. vaginalis Fe-hydrogenase was greater than that of the recombinant entamoebic GST-entamoebic Fe-hydrogenase and was inhibited by a lysate of non-transfected entamoebas (Table 1). This may explain why it was difficult to detect Fe-hydrogenase activity in lysates of nontransfected ent- amoebas, even though Fe-hydrogenase 1 mRNAs were identified from them by RT-PCR (next section). Cultured entamoehas and giurdiiifi exprexx mRNAs en- coding short Fe-hydrogenases. We isolated an fe-hydroge- nase gene of G. lanihlia. because we have frequently com- pared the fermentation enzymes of this diplomonad with those of E. hixtolytieu (Rosenthal et 1997; Field et ul., 2000; Nixon et ul., 2002). A search of the contigs predicted from the G. lamblia shogun sequences suggested that this gene, which predicts a short Fe-hydrogenase. is the only hydrogenase gene present within the giardial genome. Like the entamoebic Fe-hydrogenase 1. the predicted giardial Fe-hydrogenase lacked an N-terminal organelle-targeting sequence and had two ferredoxin-like iron-sulfur centers and a hydrogenase iron-sulfur center like those present in the short Fe-hydrogenases of T. vugimilis, Desulfovibrio sp., and Clostridiu sp. iCammark. 1992; Thompson et ai, 1994; Bui and Johnson. 1496; Homer el ul., 1996; Nicole! et ai. 1999). RT-PCR showed that cultured entamoebas and giar- dias contain mRNAs, which encode short Fe-hydrogenases (Fig. 1 A, B). Negative controls without RT showed that the RT-PCR was not amplifying DNA from the extracts of cultured entamoebas and giardias. Because the giardial con- tigs predicted only one Fe-hydrogenase, which is expressed, it is likely that the hydrogenase activity recently detected in cultures of giardias derives from this enzyme (Lloyd and Harris. 2002). In contrast, entamoebas appear to have a second long hydrogenase (see next section), so if entamoe- bic hydrogenase activity is present, it m
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