Poster abstracts
Poster number 22 submitted by Margaret Bohmer
Interaction of a hexameric RNA with a dodecameric protein complex to produce a stable structure without induced-fit but with conformational capture
Margaret Bohmer (College of Pharmacy, Division of Pharmaceutics and Pharmacology; Center for RNA Biology. The Ohio State University), Peixuan Guo (Center for RNA Nanobiotechnology and Nanomedicine; College of Pharmacy, Division of Pharmaceutics and Pharmacology; College of Medicine and James CCC; Center for RNA Biology. The Ohio State University)
Abstract:
DsDNA translocation is ubiquitous in living systems for diverse biological functions such as cell mitosis, bacterial binary fission, DNA replication, genome trafficking, DNA repair, homologous recombination, viral genome packaging, and nuclear transport. A common sequential revolving mechanism without rotation using the asymmetrical ATPases has been used by nature to avoid coiling and tangling while translocating the lengthy dsDNA genome, as reported in bacteriophages, human viruses, and bacteria. The DNA packaging motor of the phi29 is a prototype model in dsDNA translocation. The motor uses a six-subunit pRNA ring to gear the motion for dsDNA translocation. How can six copies of pRNA associate with the 12-submit motor protein? If such mismatch is due to the quasi-equilibrium to enforce the RNA-protein interaction, then what is the novel mechanism for such interaction? In this study, we constructed chimeric pRNA with doubled size and revealed that the stoichiometry of the biologically active pRNA on the motor is a common multiple of 2 and 3, which is 6. We evaluate the data from combinational approaches including crosslinking, complementary modification, AFM, and computation modeling to assess the interaction of the pRNA structure. Our new structural analysis reveals that the phi29 pRNA hexameric ring contains 12 protruding regions, each pRNA contributing two regions, to bind to the three positively charged amino acids (Arg-Lys-Arg) of each connector subunit extending from the N-terminal of the motor connector.
Keywords: DNA packaging, RNA structure, ATPase