Functional analysis of the protein IdiC (ORF5) being expressed in elevated amounts in Synechococcus elongatus PCC 7942 in the late growth phase or under iron limitation

• Applicant: Professorin Dr. Dorothee Staiger, since 8/2008
• Subject Area: Plant Biochemistry and Biophysics
• Term: from 2005 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5449580

The acclimation of the mesophilic unicellular cyanobacterium Synechococcus elongatus PCC 7942 to iron starvation results in an increased photosynthetic cyclic and respiratory electron flow, while the photosynthetic linear electron transport activity decreases. With respect to the photosynthetic cyclic electron transport many questions concerning its mechanism and components have remained enigmatic. At the present time, it is widely accepted that at least two different major pathways exist, one of them involving the cyanobacterial NDH-1 complex. However, an unsolved problem is that the substrate-binding subunits of this complex have so far remained unidentified in cyanobacteria. In our preliminary work, we have identified the protein IdiC, which has a molecular mass of 20.5 kDa, which contains a putative [2Fe-2S] cofactor, and which has been show to be essential for growth. IdiC has similarity to the substrate-binding subunit NuoE of the NDH-1 complex from Escherichia coli. On the basis of the so far obtained results, we suggest IdiC to be a candidate for the missing substrate-binding subunit of the cyanobacterial NDH-1 complex. The goal of this proposal is a profound characterization of IdiC with respect to its molecular properties, its localization in one of the thylakoid membrane-located multi-protein complexes, and an investigation of the mechanisms controlling its expression. Moreover, we intend to find further evidence for the participation of IdiC in the photosynthetic electron transport.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Privatdozent Dr. Klaus-Peter Michel, until 8/2008