| Autor: |
Macorano L; Institute of Microbial Cell Biology, Department of Biology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany., Binny TM; Institute of Microbial Cell Biology, Department of Biology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany., Spiegl T; Institute of Microbial Cell Biology, Department of Biology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany., Klimenko V; Institute of Microbial Cell Biology, Department of Biology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany., Singer A; Institute of Microbial Cell Biology, Department of Biology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany., Oberleitner L; Institute of Microbial Cell Biology, Department of Biology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany., Applegate V; Center for Structural Studies, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany., Seyffert S; Institute of Microbial Cell Biology, Department of Biology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany., Stefanski A; Molecular Proteomics Laboratory, Medical Faculty and University Hospital, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany., Gremer L; Institute of Biological Information Processing (IBI-7 Structural Biochemistry) and JuStruct Jülich Center of Structural Biology, Forschungszentrum Jülich, 52428 Jülich, Germany.; Institute of Physical Biology, Department of Biology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany., Gertzen CGW; Center for Structural Studies, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany.; Institute for Pharmaceutical and Medicinal Chemistry, Department of Pharmacy, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany., Höppner A; Center for Structural Studies, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany., Smits SHJ; Center for Structural Studies, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany.; Institute of Biochemistry, Department of Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany., Nowack ECM; Institute of Microbial Cell Biology, Department of Biology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany. |
| Abstrakt: |
The chromatophores in Paulinella are evolutionary-early-stage photosynthetic organelles. Biological processes in chromatophores depend on a combination of chromatophore and nucleus-encoded proteins. Interestingly, besides proteins carrying chromatophore-targeting signals, a large arsenal of short chromatophore-targeted proteins (sCTPs; <90 amino acids) without recognizable targeting signals were found in chromatophores. This situation resembles endosymbionts in plants and insects that are manipulated by host-derived antimicrobial peptides. Previously, we identified an expanded family of sCTPs of unknown function, named here "DNA-binding (DB)-sCTPs". DB-sCTPs contain a ~45 amino acid motif that is conserved in some bacterial proteins with predicted functions in DNA processing. Here, we explored antimicrobial activity, DNA-binding capacity, and structures of three purified recombinant DB-sCTPs. All three proteins exhibited antimicrobial activity against bacteria involving membrane permeabilization, and bound to bacterial lipids in vitro. A combination of in vitro assays demonstrated binding of recombinant DB-sCTPs to chromatophore-derived genomic DNA sequences with an affinity in the low nM range. Additionally, we report the 1.2 Å crystal structure of one DB-sCTP. In silico docking studies suggest that helix α2 inserts into the DNA major grove and the exposed residues, that are highly variable between different DB-sCTPs, confer interaction with the DNA bases. Identification of photosystem II subunit CP43 as a potential interaction partner of one DB-sCTP, suggests DB-sCTPs to be involved in more complex regulatory mechanisms. We hypothesize that membrane binding of DB-sCTPs is related to their import into chromatophores. Once inside, they interact with the chromatophore genome potentially providing nuclear control over genetic information processing. |
