Dual localized AtHscB involved in iron sulfur protein biogenesis in Arabidopsis.
BACKGROUND
Iron-sulfur clusters are ubiquitous structures which act as prosthetic groups for numerous proteins involved in several fundamental biological processes including respiration and photosynthesis. Although simple in structure both the assembly and insertion of clusters into apoproteins requires complex biochemical pathways involving a diverse set of proteins. In yeast, the J-type chaperone Jac1 plays a key role in the biogenesis of iron sulfur clusters in mitochondria.


RESULTS
In this study we demonstrate that AtHscB from Arabidopsis can rescue the Jac1 yeast knockout mutant suggesting a role for AtHscB in iron sulfur protein biogenesis in plants. In contrast to mitochondrial Jac1, AtHscB localizes to both mitochondria and the cytosol. AtHscB interacts with AtIscU1, an Isu-like scaffold protein involved in iron-sulfur cluster biogenesis, and through this interaction AtIscU1 is most probably retained in the cytosol. The chaperone AtHscA can functionally complement the yeast Ssq1knockout mutant and its ATPase activity is enhanced by AtHscB and AtIscU1. Interestingly, AtHscA is also localized in both mitochondria and the cytosol. Furthermore, AtHscB is highly expressed in anthers and trichomes and an AtHscB T-DNA insertion mutant shows reduced seed set, a waxless phenotype and inappropriate trichome development as well as dramatically reduced activities of the iron-sulfur enzymes aconitase and succinate dehydrogenase.


CONCLUSIONS
Our data suggest that AtHscB together with AtHscA and AtIscU1 plays an important role in the biogenesis of iron-sulfur proteins in both mitochondria and the cytosol.
Center of Organelle Research, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway.
Xiang Ming
XM
Xu
Hong
H
Lin
Maita
M
Latijnhouwers
Simon Geir
SG
Møller
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D005816:Genetic Complementation Test; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000502:physiology*; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000502:physiology*; D018832:Molecular Chaperones / Q000235:genetics*; D009154:Mutation; D010101:Oxygen Consumption; D010641:Phenotype; D010788:Photosynthesis; D030821:Plants, Genetically Modified; D010957:Plasmids / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D013385:Succinate Dehydrogenase / Q000737:chemistry; D014157:Transcription Factors
D029681:Arabidopsis Proteins; C546127:HscB protein, Arabidopsis; D007506:Iron-Sulfur Proteins; C115914:JAC1 protein, S cerevisiae; D024101:Mitochondrial Proteins; D018832:Molecular Chaperones; D029701:Saccharomyces cerevisiae Proteins; C525633:TCL1 protein, Arabidopsis; D014157:Transcription Factors; D013385:Succinate Dehydrogenase; D000251:Adenosine Triphosphatases