Elongator complex

Ma, K., Temiakov, D., Jiang, M., Anikin, M., and McAllister, W.T. (2002) Major conformational changes occur during the transition from an initiation complex to an elongation complex by T7 RNA polymerase./. Biol. Chem. 277, 43206-43215. 

Marr, M.T., Datwyler, S.A., Meares, C.F., and Roberts, J.W. (2001) Restructuring of an RNA polymerase holoenzyme elongation complex by lambdoid phage Q proteins. PNAS 98, 8972-8978. 

In addition, they assist in replication of RNA viruses, another process that requires RNA synthesis. Viruses sometimes make use of host RNA polymerases but often synthesize their own catalytic subunits. Bacteriophage T4 uses the E. coli RNA polymerase and o factors but modifies their action through the binding of several phage-encoded proteins.248 In contrast, phage T7 encodes its own relatively simple RNAP whose initiation complex (Section A,2)29 and elongation complexes have been studied 249-249b... 

As the polymerase traverses the DNA, it must continually cause a melting or strand separation of the DNA so that a single DNA template strand is available at the active site of the enzyme. During elongation, one base pair re-forms behind the active site for every base pair opened in front of it. The short transient RNA-DNA hybrid duplex that forms between the newly synthesized RNA and the unpaired region of the DNA helps to hold the RNA to the elongating complex. 

Nudler, E. Avetissova, E. Markovstov, V. Goldfarb, A. Transcription pro-cessivity protein-DNA interactions holding together the elongation complex. Science 1996 273 211-217. 

Zhou, W. and Doetsch, P.W. (1994) Transcription bypass or blockage at single-strand breaks on the DNA template strand effed of different 3 and 5 flanking groups on the T7 RNA polymerase elongation complex. Biochemistry, 33, 14926-14934. 

Wang, Z. and Rana, T.M. (1997) DNA damage-dependent transcriptional arrest and termination of RNA polymerase II elongation complexes in DNA template containing HIV-1 promoter. Proc. Natl. Acad. Sci. USA,... 

RNA polymerase (4) ATP Multisubunit polymerase within transcription elongation complex Nucleus Translocation along DNA during transcription... 

Transcriptional termination in E. coli is either protein-dependent, which is mediated by a termination protein (r) that associates with the RNA polymerase elongation complex and cause template disengagement, or protein-independent, a mechanism that involves the formation of an inhibitory stem-loop structure. 

Kainz M., Roberts J. (1992) Structure of transcription elongation complexes in vivo. Science 255 838. 

Eukaryotic mRNAs contain an unusual 7-methyl guanosine at the 50 end of the transcript called a 50 cap. This guanosine is added to the transcript shortly after RNA synthesis is initiated by enzymes associated with the RNA pol II elongation complex. There is an unusual 50,50-triphosphate linkage in the 50 cap between the guanosine and the first nucleotide of the mRNA (usually adenine), as shown in Figure 25.9. 

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