The cyanobacterial cell division factor Ftn6 contains an N-terminal DnaD-like domain.
BACKGROUND
DNA replication and cell cycle as well as their relationship have been extensively studied in the two model organisms E. coli and B. subtilis. By contrast, little is known about these processes in cyanobacteria, even though they are crucial to the biosphere, in utilizing solar energy to renew the oxygenic atmosphere and in producing the biomass for the food chain. Recent studies have allowed the identification of several cell division factors that are specifics to cyanobacteria. Among them, Ftn6 has been proposed to function in the recruitment of the crucial FtsZ proteins to the septum or the subsequent Z-ring assembly and possibly in chromosome segregation.


RESULTS
In this study, we identified an as yet undescribed domain located in the conserved N-terminal region of Ftn6. This 77 amino-acids-long domain, designated here as FND (Ftn6 N-Terminal Domain), exhibits striking sequence and structural similarities with the DNA-interacting module, listed in the PFAM database as the DnaD-like domain (pfam04271). We took advantage of the sequence similarities between FND and the DnaD-like domains to construct a homology 3D-model of the Ftn6 FND domain from the model cyanobacterium Synechocystis PCC6803. Mapping of the conserved residues exposed onto the FND surface allowed us to identify a highly conserved area that could be engaged in Ftn6-specific interactions.


CONCLUSIONS
Overall, similarities between FND and DnaD-like domains as well as previously reported observations on Ftn6 suggest that FND may function as a DNA-interacting module thereby providing an as yet missing link between DNA replication and cell division in cyanobacteria. Consistently, we also showed that Ftn6 is involved in tolerance to DNA damages generated by UV rays.
Marbouty
Martial
M
CEA, iBiTec-S, SBIGeM, LBI, Bat 142 CEA-Saclay, F-91191 Gif sur Yvette CEDEX, France. martial.marbouty@gmail.com
Saguez
Cyril
C
Chauvat
Franck
F
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D004249:DNA Damage; D004269:DNA, Bacterial / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000737:chemistry*; D017353:Gene Deletion; D050296:Microbial Viability / Q000528:radiation effects; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D046939:Synechocystis / Q000737:chemistry* / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins
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