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Abstract
RhdA-SSH could function as escort protein during sulfur mobilization processes. E.coli IscS promote the RhdA persulfuration, that exhibits Michaelis-Menten behaviour. Both A. vinelandii cysteine desulfurases were able to generate RhdA-SSH but only NifS exhibits Michaelis-Menten behaviour. The NifS alanine activity resulted higher than that of IscS; in the presence of RhdA, the IscS activity was increased up to 58%. Formation of IscS-SSH was higher than that of NifS-SSH; in the presence of RhdA, the persulfuration of both cysteine desulfurases was increased. Size-exclusion and affinity chromatography were carried out to search possible metabolic interactions of RhdA-SSH. Unfortunately, we were not able to define whether a complex between RhdA and the cysteine desulfurases or some other interacting proteins could be formed. Using an A. vinelandii strain lacking rhdA gene and an E. coli strain lacking sseA gene, we characterized some response to induced oxidative stress. A vinelandii UW136
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and MV474 did not show any difference in growth in BSN medium but in diazothophic conditions, MV474 showed impairment in growing as compared to the wild type strain. Moreover, it was found that the RhdA null mutant was more prone than the wild-type strain to oxidative stress. No one of the growing conditions where the lack of RhdA inferred growing deficiency of A. vinelandii, was found alter growth of E. coli sseA6, as compared to the wild-type strain. Analysis in oxidative stress condition, (PMS or H2O2), did not underline any difference in growth between the wild type and the mutant strains. These results enhance the idea that structural features of the widespread rhodanese-like proteins make them functional devices in different metabolic context.
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Archivio Tesi di dottorato
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| 3783 | |
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| D. 2009 0020 |
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