Functional Characterization of Fdx1: Evidence for an Evolutionary Relationship between P450-Type and ISC-Type Ferredoxins

Ewen, Kerstin Maria; Hannemann, Frank; Iametti, Stefania; Morleo, Anna; Bernhardt, Rita

doi:10.1016/j.jmb.2011.09.010

Cited by 21 publications

(14 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…S2A in the supplemental material) may have occurred with the aid of cluster I Fdx and cluster R FdR in strain UT26. In contrast to cluster I Fdxs, cluster II Fdxs are phylogenetically similar to the Fdxs involved in ISC biosynthesis (ISC-Fdxs) (44)(45)(46) (Fig. 3A).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Bacterial Cytochrome P450 System Catabolizing the Fusarium Toxin Deoxynivalenol

Ito

Sato

Ishizaka

et al. 2013

Appl Environ Microbiol

View full text Add to dashboard Cite

c Deoxynivalenol (DON) is a natural toxin of fungi that cause Fusarium head blight disease of wheat and other small-grain cereals. DON accumulates in infected grains and promotes the spread of the infection on wheat, posing serious problems to grain production. The elucidation of DON-catabolic genes and enzymes in DON-degrading microbes will provide new approaches to decrease DON contamination. Here, we report a cytochrome P450 system capable of catabolizing DON in Sphingomonas sp. strain KSM1, a DON-utilizing bacterium newly isolated from lake water. The P450 gene ddnA was cloned through an activity-based screening of a KSM1 genomic library. The genes of its redox partner candidates (flavin adenine dinucleotide [FAD]-dependent ferredoxin reductase and mitochondrial-type [2Fe-2S] ferredoxin) were not found adjacent to ddnA; the redox partner candidates were further cloned separately based on conserved motifs. The DON-catabolic activity was reconstituted in vitro in an electron transfer chain comprising the three enzymes and NADH, with a catalytic efficiency (k cat /K m ) of 6.4 mM ؊1 s ؊1 . The reaction product was identified as 16-hydroxy-deoxynivalenol. A bioassay using wheat seedlings revealed that the hydroxylation dramatically reduced the toxicity of DON to wheat. The enzyme system showed similar catalytic efficiencies toward nivalenol and 3-acetyl deoxynivalenol, toxins that frequently cooccur with DON. These findings identify an enzyme system that catabolizes DON, leading to reduced phytotoxicity to wheat.

show abstract

Section: Discussionmentioning

confidence: 99%

“…3B). The corresponding residue of cluster II Fdxs, which are relatively closely related to the Fdxs involved in ISC biosynthesis (ISCFdxs) (44)(45)(46), was a serine (Fig. 3B).…”

Section: Identification Of Potential Redox Partner Genesmentioning

confidence: 99%

Bacterial Cytochrome P450 System Catabolizing the Fusarium Toxin Deoxynivalenol

Ito

Sato

Ishizaka

et al. 2013

Appl Environ Microbiol

View full text Add to dashboard Cite

show abstract

“…The HscB/holoIscU complex transfers its cluster to apoproteins at slow rates, unless HscA and ATP are present, and thus may represent a convenient "buffer" systems for relatively stable storage of excess amounts of FeS clusters when acceptor apoproteins are not available. Also, formation of the "mature" holoIscU may be instrumental to relatively facile formation of FeS clusters of different nuclearity through redox-dependent (but chaperone-independent) events [5,10,29]. Should the need arise, HscA/HscB/ATP may intervene to accelerate-in regulated fashion-the release of the cluster stored in a stable form on "mature" holoIscU [6] regardless of whether it is free of HscB-bound.…”

Section: Discussionmentioning

confidence: 99%

“…However, transfer of 4Fe4S clusters, whose formation on IscU is facilitated by redox events possibly involving specific isc-encoded partners [9,10], has been shown to be insensitive to HscA/HscB and ATP [5], and other systems may be involved in the maturation of nitrogenase [11]. The interaction among homologs of IscU and HscA/HscB has been demonstrated to be essential in plant [12] and human mitochondria [13].…”

Section: Introductionmentioning

confidence: 99%

“…These issues are relevant to the two hypothesized roles for IscU, that may act either a catalyst of FeS cluster biosynthesis or as a "reservoir" of pre-assembled clusters to be delivered when required (in a HscA/HscB/ATP-dependent manner). The original cluster on holoIscU may also be transformed through suitable redox chemistry [6,9,10] in clusters of nuclearity other than 2Fe-2S. The occurrence of multiple functions of this protein would make it capable of satisfying a variety of cellular needs in terms of biosynthesis of FeS structures, while minimizing the potentially dangerous effects of unstable iron ligation [23].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Functional implications of the interaction between HscB and IscU in the biosynthesis of FeS clusters

2015

Self Cite

View full text Add to dashboard Cite

In bacteria, HscB is the cochaperone of HscA in modulating the transfer of 2Fe2S clusters from a cluster-loaded form of the scaffold protein IscU to acceptor apoproteins. HscB binding to the IscU apoform (apoIscU) reportedly impairs the structural flexibility of apoIscU, but the effects of HscB on cluster formation on IscU have never been assessed. We report that presence of HscB impaired the rate-but not the equilibrium-of the appearance of the distinctive circular dichroism signals associated with formation of a stable 2Fe-2S cluster on IscU in reconstitution experiments. This impairment: (1) was independent of the source of cluster sulfide; (2) was not observed for HscB mutants unable to bind IscU; (3) implied formation of a 1/1 HscB/IscU complex; (4) was not observed for a D39A mutant of IscU, with a much more rigid structure than wt IscU. The cluster species assembled on IscU in the presence of HscB were transferred to apoferredoxin at a slower rate than those formed in the absence of HscB, unless ATP and HscA were also present. At contrast, HscB was found to improve the "catalytic" function of IscU with respect to cluster assembly in the presence of a large apoferredoxin excess. Thus, the HscB/IscU interaction may modulate formation and transfer of FeS clusters by accelerating cluster biosynthesis when appropriate target apoproteins are abundant or by slowing it down when the rate of apoprotein synthesis is slow, and cluster-loaded IscU is more likely to play a role as a "FeS storage" protein.

show abstract