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Gene Review

infB  -  translation initiation factor IF-2

Escherichia coli str. K-12 substr. MG1655

Synonyms: ECK3157, JW3137, gicD, ssyG
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Disease relevance of infB

  • The existence of two genes between infB and rpsO in the Escherichia coli genome: DNA sequencing and S1 nuclease mapping [1].
  • Using a strain that carries a null mutation in the chromosomal copy of infB and a functional copy of the same gene on a thermosensitive lysogenic lambda phage, we could cure the lambda phage when the plasmids expressing only one form of IF2 were supplied in trans [2].
  • We reported previously the cloning and sequence of the Bacillus subtilis infB gene which encodes the essential IF2 factor required for initiation of translation (K. Shazand, J. Tucker, R. Chiang, K. Stansmore, H. U. Sperling-Petersen, M. Grunberg-Manago, J. C. Rabinowitz, and T. Leighton, J. Bacteriol. 172:2675-2687, 1990) [3].
  • A further search in the readily available public sequence databases revealed that infB from Yersinia pestis also contains an intracistronic in-frame initiation site used for the translation of IF2beta [4].
  • Identification, cloning and sequence of the Streptococcus faecium infB (translational initiation factor IF2) gene [5].

High impact information on infB


Biological context of infB

  • In the spacer region of 24 base pairs between the nusA and infB structural genes there is no significant DNA sequence that fits the canonical transcriptional termination signal or promoter sequence [9].
  • Both forms are products of the gene infB with translational initiation at codon 1 (AUG) and codon 158 (GUG) in the same reading frame [10].
  • CONCLUSION: Efficient intracistronic translation initiation of the infB gene is suggested to require an mRNA with this special base composition that results in an open, single-stranded structure at the ribosomal binding region [4].
  • The structural gene for translation initiation factor IF2 from Thermus thermophilus was identified on the basis of the N-terminal amino acid sequence of intact T thermophilus IF2 and an internal 25 kDa IF2 fragment [11].

Anatomical context of infB

  • In order to examine whether the feedback loop involves the ribosomes' main function, translation, we have constructed a strain in which the chromosomal copy of infB, encoding IF2, was placed under lac promoter/operator control, and the effects of limitation of translation initiation factor IF2 on the regulation were examined [12].

Associations of infB with chemical compounds

  • The base composition in a part of the 5' end of the DNA coding strand of the enterobacterial infB gene shows a strong preference for adenine (A) over thymine (T) with a maximum ratio of A-to-T around the intracistronic initiation sites [4].

Analytical, diagnostic and therapeutic context of infB


  1. The existence of two genes between infB and rpsO in the Escherichia coli genome: DNA sequencing and S1 nuclease mapping. Sands, J.F., Regnier, P., Cummings, H.S., Grunberg-Manago, M., Hershey, J.W. Nucleic Acids Res. (1988) [Pubmed]
  2. Both forms of translational initiation factor IF2 (alpha and beta) are required for maximal growth of Escherichia coli. Evidence for two translational initiation codons for IF2 beta. Sacerdot, C., Vachon, G., Laalami, S., Morel-Deville, F., Cenatiempo, Y., Grunberg-Manago, M. J. Mol. Biol. (1992) [Pubmed]
  3. Similar organization of the nusA-infB operon in Bacillus subtilis and Escherichia coli. Shazand, K., Tucker, J., Grunberg-Manago, M., Rabinowitz, J.C., Leighton, T. J. Bacteriol. (1993) [Pubmed]
  4. Structural requirements of the mRNA for intracistronic translation initiation of the enterobacterial infB gene. Laursen, B.S., de A Steffensen, S.A., Hedegaard, J., Moreno, J.M., Mortensen, K.K., Sperling-Petersen, H.U. Genes Cells (2002) [Pubmed]
  5. Identification, cloning and sequence of the Streptococcus faecium infB (translational initiation factor IF2) gene. Friedrich, K., Brombach, M., Pon, C.L. Mol. Gen. Genet. (1988) [Pubmed]
  6. Sequence of the initiation factor IF2 gene: unusual protein features and homologies with elongation factors. Sacerdot, C., Dessen, P., Hershey, J.W., Plumbridge, J.A., Grunberg-Manago, M. Proc. Natl. Acad. Sci. U.S.A. (1984) [Pubmed]
  7. In vitro study of two dominant inhibitory GTPase mutants of Escherichia coli translation initiation factor IF2. Direct evidence that GTP hydrolysis is necessary for factor recycling. Luchin, S., Putzer, H., Hershey, J.W., Cenatiempo, Y., Grunberg-Manago, M., Laalami, S. J. Biol. Chem. (1999) [Pubmed]
  8. Effects of guanosine 3',5'-bisdiphosphate (ppGpp) on rate of transcription elongation in isoleucine-starved Escherichia coli. Vogel, U., Jensen, K.F. J. Biol. Chem. (1994) [Pubmed]
  9. The nucleotide sequence of the cloned nusA gene and its flanking region of Escherichia coli. Ishii, S., Ihara, M., Maekawa, T., Nakamura, Y., Uchida, H., Imamoto, F. Nucleic Acids Res. (1984) [Pubmed]
  10. Tandem translation of E. coli initiation factor IF2 beta: purification and characterization in vitro of two active forms. Nyengaard, N.R., Mortensen, K.K., Lassen, S.F., Hershey, J.W., Sperling-Petersen, H.U. Biochem. Biophys. Res. Commun. (1991) [Pubmed]
  11. Organization of the Thermus thermophilus nusA/infB operon and overexpression of the infB gene in Escherichia coli. Vornlocher, H.P., Kreutzer, R., Sprinzl, M. Biochimie (1997) [Pubmed]
  12. Feedback regulation of rRNA synthesis in Escherichia coli. Requirement for initiation factor IF2. Cole, J.R., Olsson, C.L., Hershey, J.W., Grunberg-Manago, M., Nomura, M. J. Mol. Biol. (1987) [Pubmed]
  13. E. coli translation initiation factor IF2--an extremely conserved protein. Comparative sequence analysis of the infB gene in clinical isolates of E. coli. Steffensen, S.A., Poulsen, A.B., Mortensen, K.K., Sperling-Petersen, H.U. FEBS Lett. (1997) [Pubmed]
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