RpoN

RNA polymerase sigma-54 factor
Identifiers
Organism?
SymbolRpoN
UniProtP24255

The gene rpoN (RNA polymerase, nitrogen-limitation N) encodes the sigma factor sigma-54 (σ54, sigma N, or RpoN), a protein in Escherichia coli and other species of bacteria. RpoN antagonizes RpoS sigma factors.[1]

Biological role

Originally identified as a regulator of genes involved in nitrogen metabolism and assimilation under nitrogen limiting conditions,[2] E. coli σ54 has since been shown to play important regulatory roles in a variety of other cellular processes. Similarly, σ54 homologues in other species regulate a wide range of processes, including flagellar synthesis and virulence.[3]

Sequence specificity and mechanism of action

Sigma-54 factor, Activator interacting domain
Identifiers
SymbolSigma54_AID
PfamPF00309
InterProIPR000394
PROSITEPS50044

σ54 promoter elements consist of conserved nucleotides located at −12 and −24 with respect to the transcription start site.[4] This contrasts with members of the σ70 family, which recognize conserved promoter elements located at roughly −10 and −35 with respect to the transcription start site.[5] Unlike the members of the σ70 family, σ54 proteins have been shown to bind promoter DNA independent of core RNAPin vitro.[6] Another distinguishing characteristic of σ54 proteins is their absolute requirement for activator proteins, known as bacterial enhancer binding proteins (bEBPs), to initiate transcription.[4][7] Thus, both active and inactive forms of RNAP:σ54 are bound at promoters.[8]

The RpoN-regulated promoter elements have the consensus sequence as follows: TTGGCACGGTTTTTGCT.[9]

References

  1. ↑ Dong T, Yu R, Schellhorn H (January 2011). "Antagonistic regulation of motility and transcriptome expression by RpoN and RpoS in Escherichia coli". Molecular Microbiology. 79 (2): 375–86. doi:10.1111/j.1365-2958.2010.07449.x. PMID 21219458.
  2. ↑ Hunt TP, Magasanik B (December 1985). "Transcription of glnA by purified Escherichia coli components: core RNA polymerase and the products of glnF, glnG, and glnL". Proceedings of the National Academy of Sciences of the United States of America. 82 (24): 8453–7. Bibcode:1985PNAS...82.8453H. doi:10.1073/pnas.82.24.8453. PMC 390934. PMID 2867543.
  3. ↑ Tsang J, Hoover TR (2014). "Themes and Variations: Regulation of RpoN-Dependent Flagellar Genes across Diverse Bacterial Species". Scientifica. 2014: 681754. doi:10.1155/2014/681754. PMC 3930126. PMID 24672734.
  4. 1 2 Wigneshweraraj S, Bose D, Burrows PC, Joly N, Schumacher J, Rappas M, Pape T, Zhang X, Stockley P, Severinov K, Buck M (May 2008). "Modus operandi of the bacterial RNA polymerase containing the sigma54 promoter-specificity factor". Molecular Microbiology. 68 (3): 538–46. doi:10.1111/j.1365-2958.2008.06181.x. PMID 18331472. S2CID 33750977.
  5. ↑ Gruber TM, Gross CA (2003). "Multiple sigma subunits and the partitioning of bacterial transcription space". Annual Review of Microbiology. 57: 441–66. doi:10.1146/annurev.micro.57.030502.090913. PMID 14527287.
  6. ↑ Buck M, Cannon W (July 1992). "Specific binding of the transcription factor sigma-54 to promoter DNA". Nature. 358 (6385): 422–4. Bibcode:1992Natur.358..422B. doi:10.1038/358422a0. PMID 1641025.
  7. ↑ Shingler V (May 2011). "Signal sensory systems that impact σ⁵⁴ -dependent transcription". FEMS Microbiology Reviews. 35 (3): 425–40. doi:10.1111/j.1574-6976.2010.00255.x. PMID 21054445.
  8. ↑ Bonocora RP, Smith C, Lapierre P, Wade JT (October 2015). "Genome-Scale Mapping of Escherichia coli σ54 Reveals Widespread, Conserved Intragenic Binding". PLOS Genetics. 11 (10): e1005552. doi:10.1371/journal.pgen.1005552. PMC 4591121. PMID 26425847.
  9. ↑ Leang C, Krushkal J, Ueki T, Puljic M, Sun J, Juárez K, Núñez C, Reguera G, DiDonato R, Postier B, Adkins RM, Lovley DR (July 2009). "Genome-wide analysis of the RpoN regulon in Geobacter sulfurreducens". BMC Genomics. 10: 331. doi:10.1186/1471-2164-10-331. PMC 2725144. PMID 19624843.
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