SPT5 is analogous to which bacterial elongation factor?
SPT5, together with SPT4 forms DSIF transcription elongation complex in eukaryotes, regulating pause release near promoters. Its bacterial counterpart NusG shares conserved NGN domain that contacts clamp domain of RNA polymerase and KOW domains that bind nascent RNA or ribosome. Both factors increase processivity, suppress backtracking, and coordinate transcription with co-transcriptional events: NusG in bacteria bridging RNA polymerase to ribosome or Rho terminator, SPT5 in eukaryotes to chromatin modification machinery and capping. SPT5 C-terminal repeats phosphorylated by P-TEFb CDK9 analog
Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 10: SPT5 analogous to bacterial NusG; Alberts 7th ed., Conserved elongation factor NusG homology
