Molecular architecture of an E. faecalis antitermination protein bound to RNA

Walshe JL, Patel K and Ataide SF

University of Sydney.

Regulated transcription termination provides an efficient and responsive means to control gene expression. Rho-independent termination occurs through the formation of a RNA stem-loop which disrupts the RNA polymerase elongation complex. To overcome this, bacteria may use anti-termination, whereby a mutually exclusive RNA structure is formed. In some cases this alternative structure is stabilised by ANTAR domains of proteins, preventing termination. We have determined the novel 3.8 Å crystal structure of the stabilising anti-terminator protein EutV, bound to RNA. Our studies highlight the key interactions between conserved EutV residues and the RNA, as well as protein conformational changes undergone upon RNA binding. This has allowed us to propose a broad model for ANTAR domain anti-termination.