Addition of the fourth nucleotide on the nascent HIV-1 transcript: Second Transition

Stable Identifier
Reaction [BlackBoxEvent]
Homo sapiens
Related Species
Human immunodeficiency virus 1
Locations in the PathwayBrowser

Formation of the third phosphodiester bond creates a 4-nt product. This commits the initiation complex to promoter escape. The short 4-nt transcript is still loosely associated with the RNA polymerase II initiation complex and can dissociate to yield abortive products, which are not further extended. Inhibition of ATP-hydrolysis by TFIIH does not lead to collapse of the open region any longer. The transcription complex has lost the sensitivity to single-stranded oligo-nucleotide inhibition. However, ATP-hydrolysis and TFIIH are required for efficient promoter escape. The open region ("transcription bubble") expands concomitant with the site of RNA-extension. In this case this region spans positions -9 to +4.

Literature References
PubMed ID Title Journal Year
9405375 Three transitions in the RNA polymerase II transcription complex during initiation.

Holstege, FC, Fiedler, U, Timmers, HT

EMBO J 1998
11784853 Translocation after synthesis of a four-nucleotide RNA commits RNA polymerase II to promoter escape.

Kugel, JF, Goodrich, JA

Mol Cell Biol 2002
Participant Of
Catalyst Activity
Catalyst Activity
DNA-directed 5'-3' RNA polymerase activity of RNA Polymerase II (unphosphorylated):TFIIF complex [nucleoplasm]
Physical Entity
Inferred From
Name Identifier Synonyms
Human immunodeficiency virus infectious disease 526 HIV infection