Gene Symbol: infB
Description: translation initiation factor IF-2
Alias: ECK3157, JW3137, gicD, ssyG
Species: Escherichia coli str. K-12 substr. MG1655

Top Publications

  1. Mayer C, Köhrer C, Kenny E, Prusko C, RajBhandary U. Anticodon sequence mutants of Escherichia coli initiator tRNA: effects of overproduction of aminoacyl-tRNA synthetases, methionyl-tRNA formyltransferase, and initiation factor 2 on activity in initiation. Biochemistry. 2003;42:4787-99 pubmed
    ..Other results suggest that the C1xA72 base pair mismatch, unique to eubacterial and organellar initiator tRNAs, may also be important for the binding of fAA-tRNA to IF2. ..
  2. Boelens R, Gualerzi C. Structure and function of bacterial initiation factors. Curr Protein Pept Sci. 2002;3:107-19 pubmed
    ..In this article we outline the translation initiation process in bacteria and review these recent developments giving a summary of the main features of the structure and function of the initiation factors. ..
  3. Antoun A, Pavlov M, Lovmar M, Ehrenberg M. How initiation factors tune the rate of initiation of protein synthesis in bacteria. EMBO J. 2006;25:2539-50 pubmed
    ..The reasons why IF1 and IF3 are essential in E. coli are discussed in the light of the present observations. ..
  4. Laursen B, Sørensen H, Mortensen K, Sperling Petersen H. Initiation of protein synthesis in bacteria. Microbiol Mol Biol Rev. 2005;69:101-23 pubmed
    ..The future challenge is to obtain atomic-resolution structures of complete initiation complexes in order to understand the mechanism of translation initiation in molecular detail. ..
  5. Wu X, RajBhandary U. Effect of the amino acid attached to Escherichia coli initiator tRNA on its affinity for the initiation factor IF2 and on the IF2 dependence of its binding to the ribosome. J Biol Chem. 1997;272:1891-5 pubmed
    ..Using gel mobility shift assay, we have measured the apparent Kd values of the IF2.formylaminoacyl-tRNA binary complexes. These are 1.8, 3.5, and 10.5 microM for fMet-tRNA, fVal-tRNA, and fGln-tRNA, respectively. ..
  6. Studer S, Joseph S. Unfolding of mRNA secondary structure by the bacterial translation initiation complex. Mol Cell. 2006;22:105-15 pubmed
    ..We show that unfolding of structured mRNAs requires a SD sequence, the start codon, fMet-tRNA(fMet), and the GTP bound form of initiation factor 2 bound to the 30S subunit. ..
  7. Grill S, Gualerzi C, Londei P, Blasi U. Selective stimulation of translation of leaderless mRNA by initiation factor 2: evolutionary implications for translation. EMBO J. 2000;19:4101-10 pubmed
  8. Grill S, Moll I, Hasenöhrl D, Gualerzi C, Blasi U. Modulation of ribosomal recruitment to 5'-terminal start codons by translation initiation factors IF2 and IF3. FEBS Lett. 2001;495:167-71 pubmed
  9. Ganoza M, Aoki H, Burkhardt N, Murphy B. The ribosome as affinity matrix': efficient purification scheme for translation factors. Biochimie. 1996;78:51-61 pubmed
    ..The procedure markedly simplifies the isolation, in homogeneous form, of all the non-ribosomal proteins required to reconstruct translation. ..

More Information


  1. Rodnina M, Stark H, Savelsbergh A, Wieden H, Mohr D, Matassova N, et al. GTPases mechanisms and functions of translation factors on the ribosome. Biol Chem. 2000;381:377-87 pubmed
    ..GTP hydrolysis by IF2 is triggered upon formation of the 70S initiation complex, and the dissociation of Pi and/or IF2 follows a rearrangement of the ribosome into the elongation-competent state. ..
  2. Lockwood A, Chakraborty P, Maitra U. A complex between initiation factor IF2, guanosine triphosphate, and fMet-tRNA: an intermediate in initiation complex formation. Proc Natl Acad Sci U S A. 1971;68:3122-6 pubmed
    ..fMet-tRNA(f) in this 70S complex reacts with puromycin to form fMet-puromycin. These results suggest that [IF 2, GTP, fMet-tRNA(f)] is an intermediate in the initiation of protein synthesis in Escherichia coli. ..
  3. Sands J, Regnier P, Cummings H, Grunberg Manago M, Hershey J. The existence of two genes between infB and rpsO in the Escherichia coli genome: DNA sequencing and S1 nuclease mapping. Nucleic Acids Res. 1988;16:10803-16 pubmed
    ..coli genome map and are transcribed clockwise as two operons: the metY operon, containing metY, P15A, nusA, infB; and about a kilobase further downstream, the rpsO and pnp operon...
  4. Vachon G, Laalami S, Grunberg Manago M, Julien R, Cenatiempo Y. Purified internal G-domain of translational initiation factor IF-2 displays guanine nucleotide binding properties. Biochemistry. 1990;29:9728-33 pubmed
    ..It is assumed that active centers of IF-2 located outside the G-domain are needed for the latter reaction.(ABSTRACT TRUNCATED AT 250 WORDS) ..
  5. Moll I, Grill S, Gualerzi C, Blasi U. Leaderless mRNAs in bacteria: surprises in ribosomal recruitment and translational control. Mol Microbiol. 2002;43:239-46 pubmed
    ..In fact, the faithful translation of leaderless mRNAs in heterologous systems shows that the ability to translate leaderless mRNAs is an evolutionarily conserved function of the translational apparatus. ..
  6. Mortensen K, Nyengaard N, Hershey J, Laalami S, Sperling Petersen H. Superexpression and fast purification of E coli initiation factor IF2. Biochimie. 1991;73:983-9 pubmed
    ..The gene infB was cloned into the thermo-inducible runaway plasmid pCP40 [1] and subsequently transformed into the E coli strain ..
  7. Antoun A, Pavlov M, Lovmar M, Ehrenberg M. How initiation factors maximize the accuracy of tRNA selection in initiation of bacterial protein synthesis. Mol Cell. 2006;23:183-93 pubmed
    ..We suggest why IF1 is essential for E. coli, discuss the role of the G-C base pairs in the anticodon stem of some tRNAs, and clarify gene expression changes with varying IF3 concentration in the living cell. ..
  8. Bae W, Xia B, Inouye M, Severinov K. Escherichia coli CspA-family RNA chaperones are transcription antiterminators. Proc Natl Acad Sci U S A. 2000;97:7784-9 pubmed
    ..of cloned CspC and CspE at 37 degrees C was sufficient to induce transcription of the metY-rpsO operon genes nusA, infB, rbfA, and pnp located downstream of multiple transcription terminators...
  9. Helgstrand M, Mandava C, Mulder F, Liljas A, Sanyal S, Akke M. The ribosomal stalk binds to translation factors IF2, EF-Tu, EF-G and RF3 via a conserved region of the L12 C-terminal domain. J Mol Biol. 2007;365:468-79 pubmed
    ..These results indicate that the L12-factor complexes will be highly populated on the ribosome, because of the high local concentration of ribosome-bound factor with respect to L12. ..
  10. Pavlov M, Zorzet A, Andersson D, Ehrenberg M. Activation of initiation factor 2 by ligands and mutations for rapid docking of ribosomal subunits. EMBO J. 2011;30:289-301 pubmed publisher
    ..Functional characterization of the A-type mutations provides keys to structural interpretation of conditional switching of IF2 and other multidomain GTPases. ..
  11. Morel Deville F, Vachon G, Sacerdot C, Cozzone A, Grunberg Manago M, Cenatiempo Y. Characterization of the translational start site for IF2 beta, a short form of Escherichia coli initiation factor IF2. Eur J Biochem. 1990;188:605-14 pubmed
    The gene for initiation factor IF2, infB, represents one of the few examples in Escherichia coli of genes encoding two protein products in vivo...
  12. Allen G, Zavialov A, Gursky R, Ehrenberg M, Frank J. The cryo-EM structure of a translation initiation complex from Escherichia coli. Cell. 2005;121:703-12 pubmed
    ..Additionally, we present evidence for the localization of IF1, IF3, one C-terminal domain of L7/L12, and the N-terminal domain of IF2 in the initiation complex. ..
  13. Rath D, Mangoli S, Mahajan S, Jawali N. A novel mutation spatially remote from the G-domain in IF2 affects the cold stress adaptation of Escherichia coli. Res Microbiol. 2009;160:576-80 pubmed publisher
    ..Complementation analysis showed gicD1 to be allelic to infB. We identify gicD1 to be a valine to isoleucine substitution in initiation factor-2 (IF2) of a residue that seems ..
  14. Qin H, Grigoriadou C, Cooperman B. Interaction of IF2 with the ribosomal GTPase-associated center during 70S initiation complex formation. Biochemistry. 2009;48:4699-706 pubmed publisher
    ..coli 70SIC, relative reactivities toward dipeptide formation of 70SICs formed with the two IF2s suggest that the Bst-IF2.GDP complex is more difficult to displace from the GAC than the E. coli IF2.GDP complex. ..
  15. Bylund G, Lövgren J, Wikström P. Characterization of mutations in the metY-nusA-infB operon that suppress the slow growth of a DeltarimM mutant. J Bacteriol. 2001;183:6095-106 pubmed
    ..Nine of these mutations were in the nusA gene, which is located upstream from rbfA in the metY-nusA-infB operon; three mutations deleted the transcriptional terminator between infB and rbfA; one was an insertion of IS2 ..
  16. Regnier P, Grunberg Manago M. RNase III cleavages in non-coding leaders of Escherichia coli transcripts control mRNA stability and genetic expression. Biochimie. 1990;72:825-34 pubmed
    The primary transcripts of the rpsO-pnp, rnc-era-recO and metY-nusA-infB operons of E coli are each processed by RNase III, upstream of the first translated gene, in hair-pin structures formed by the 5' non-coding leader...
  17. Granston A, Thompson D, Friedman D. Identification of a second promoter for the metY-nusA-infB operon of Escherichia coli. J Bacteriol. 1990;172:2336-42 pubmed
    The metY-nusA-infB operon of Escherichia coli encodes functions involved in both transcription and translation. Previous studies have identified a single promoter, P0, that directs transcription of the entire operon...
  18. Weber A, Kögl S, Jung K. Time-dependent proteome alterations under osmotic stress during aerobic and anaerobic growth in Escherichia coli. J Bacteriol. 2006;188:7165-75 pubmed
    ..The protein profiles revealed an induction of 12 proteins (Dps, HchA, HdhA, InfB, OsmC, OsmY, ProX, KatE, PspA, TalA, TktB, and TreF) under osmotic stress in an aerobic milieu...
  19. Revel M, Lelong J, Brawerman G, Gros F. Function of three protein factors and ribosomal subunits in the initiation of protein synthesis in E. coli. Nature. 1968;219:1016-21 pubmed
  20. Campbell T, Brown E. Genetic interaction screens with ordered overexpression and deletion clone sets implicate the Escherichia coli GTPase YjeQ in late ribosome biogenesis. J Bacteriol. 2008;190:2537-45 pubmed publisher
    ..Taken in context, our work is most consistent with the hypothesis that YjeQ has a role in late 30S subunit biogenesis. ..
  21. Guillon J, Heiss S, Soutourina J, Mechulam Y, Laalami S, Grunberg Manago M, et al. Interplay of methionine tRNAs with translation elongation factor Tu and translation initiation factor 2 in Escherichia coli. J Biol Chem. 1996;271:22321-5 pubmed
    ..M., Mechulam, Y., Schmitter, J.-M., Blanquet, S., and Fayat, G. (1992) J. Bacteriol. 174, 4294-4301. ..
  22. Caldon C, Yoong P, March P. Evolution of a molecular switch: universal bacterial GTPases regulate ribosome function. Mol Microbiol. 2001;41:289-97 pubmed
    ..If this is the case, then a corollary of this hypothesis is that GTPases that do not bind RNA arose at a later time from an RNA-binding progenitor that lost the capability to bind RNA. ..
  23. Antoun A, Pavlov M, Andersson K, Tenson T, Ehrenberg M. The roles of initiation factor 2 and guanosine triphosphate in initiation of protein synthesis. EMBO J. 2003;22:5593-601 pubmed
    ..Our data, indicating that eIF5B and IF2 have similar functions, are used to rationalize the phenotypes of GTPase-deficient mutants of eIF5B and IF2. ..
  24. Brandi L, Marzi S, Fabbretti A, Fleischer C, Hill W, Gualerzi C, et al. The translation initiation functions of IF2: targets for thiostrepton inhibition. J Mol Biol. 2004;335:881-94 pubmed
    ..Overall, our data indicate that the translation initiation function of IF2 is as sensitive as the translocation function of EF-G to thiostrepton inhibition. ..
  25. Rasmussen L, Oliveira C, Jensen J, Pedersen J, Sperling Petersen H, Mortensen K. Solution structure of C-terminal Escherichia coli translation initiation factor IF2 by small-angle X-ray scattering. Biochemistry. 2008;47:5590-8 pubmed publisher
    ..The chalice-like structure with a highly exposed alpha-helical stretch observed for the aIF5B crystal structure was not found in the structural model of IF2 in solution, in which domain VI-2 is moved closer to the rest of the protein. ..
  26. Regnier P, Grunberg Manago M. Cleavage by RNase III in the transcripts of the met Y-nus-A-infB operon of Escherichia coli releases the tRNA and initiates the decay of the downstream mRNA. J Mol Biol. 1989;210:293-302 pubmed
  27. Plumbridge J, Springer M. Organization of the Escherichia coli chromosome around the genes for translation initiation factor IF2 (infB) and a transcription termination factor (nusA). J Mol Biol. 1983;167:227-43 pubmed
    The genes infB, for translational initiation factor IF2, and nusA for a protein involved in transcription termination are carried on a 4.8 X 10(3) base-pair DNA fragment...
  28. Plumbridge J, Howe J, Springer M, Touati Schwartz D, Hershey J, Grunberg Manago M. Cloning and mapping of a gene for translational initiation factor IF2 in Escherichia coli. Proc Natl Acad Sci U S A. 1982;79:5033-7 pubmed
    ..Because the gene for initiation factor IF3 is located at 38 min on the chromosome, the genes for translational initiation factors are not grouped together. ..
  29. Dubnoff J, Maitra U. Characterization of the ribosome-dependent guanosine triphosphatase activity of polypeptide chain initiation factor IF 2. J Biol Chem. 1972;247:2876-83 pubmed
  30. Mangroo D, Wu X, RajBhandary U. Escherichia coli initiator tRNA: structure-function relationships and interactions with the translational machinery. Biochem Cell Biol. 1995;73:1023-31 pubmed
    ..In a miaA strain of E. coli deficient in biosynthesis of ms2i6A, the mutant initiator tRNA is much less active in initiation. The defect is specifically in binding to the ribosomal P site. ..
  31. Plumbridge J, Deville F, Sacerdot C, Petersen H, Cenatiempo Y, Cozzone A, et al. Two translational initiation sites in the infB gene are used to express initiation factor IF2 alpha and IF2 beta in Escherichia coli. EMBO J. 1985;4:223-9 pubmed
    The gene infB codes for the two forms of translational initiation factor IF2: IF2 alpha (97 300 daltons) and IF2 beta (79 700 daltons)...
  32. Laursen B, Mortensen K, Sperling Petersen H, Hoffman D. A conserved structural motif at the N terminus of bacterial translation initiation factor IF2. J Biol Chem. 2003;278:16320-8 pubmed
    ..The results of the present work will provide guidance for the design of future experiments directed toward understanding the functional roles of this widely conserved structural domain within IF2. ..
  33. Ishii S, Ihara M, Maekawa T, Nakamura Y, Uchida H, Imamoto F. The nucleotide sequence of the cloned nusA gene and its flanking region of Escherichia coli. Nucleic Acids Res. 1984;12:3333-42 pubmed
    ..reading frame encoding a polypeptide of at least 22 amino acids, which was identified as the initial portion of the infB structural gene...
  34. Shiba K, Ito K, Yura T. Suppressors of the secY24 mutation: identification and characterization of additional ssy genes in Escherichia coli. J Bacteriol. 1986;166:849-56 pubmed
    ..5 min between tsx and lon; ssyD around 3 min; ssyE at 72.5 min near secY; ssyF at 20.5 min within rpsA; and ssyG at 69.0 min near argG...
  35. Nakamura Y, Mizusawa S. In vivo evidence that the nusA and infB genes of E. coli are part of the same multi-gene operon which encodes at least four proteins. EMBO J. 1985;4:527-32 pubmed
    ..wts. 48 000 (argG), 21 000 (p21), 64 000 (nusA), 120 000 (IF2 alpha)-(infB), 91 000 (IF2 beta)(infB), 15 000 (p15), 10 000 (rpsO) and 85 000 (pnp)...
  36. Hellmuth K, Rex G, Surin B, Zinck R, McCarthy J. Translational coupling varying in efficiency between different pairs of genes in the central region of the atp operon of Escherichia coli. Mol Microbiol. 1991;5:813-24 pubmed
    ..The mechanism of this coupling was investigated using in vitro mutagenesis. At least in the case of the pair atpHA, coupling seems to involve facilitated binding of fresh ribosomes to the atpA translational initiation regions. ..
  37. Sacerdot C, Vachon G, Laalami S, Morel Deville F, Cenatiempo Y, Grunberg Manago M. 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. J Mol Biol. 1992;225:67-80 pubmed
    The gene infB codes for two forms of translational initiation factor IF2; IF2 alpha (97,300 Da) and IF2 beta (79,700 Da)...
  38. Miller M, Wahba A. Chain initiation factor 2. Purification and properties of two species from Escherichia coli MRE 600. J Biol Chem. 1973;248:1084-90 pubmed
  39. Iwasaki K, Sabol S, Wahba A, Ochoa S. Translation of the genetic message. VII. Role of initiation factors in formation of the chain initiation complex with Escherichia coli ribosomes. Arch Biochem Biophys. 1968;125:542-7 pubmed
  40. Milon P, Tischenko E, Tomsic J, Caserta E, Folkers G, La Teana A, et al. The nucleotide-binding site of bacterial translation initiation factor 2 (IF2) as a metabolic sensor. Proc Natl Acad Sci U S A. 2006;103:13962-7 pubmed
  41. Nyengaard N, Mortensen K, Lassen S, Hershey J, Sperling Petersen H. Tandem translation of E. coli initiation factor IF2 beta: purification and characterization in vitro of two active forms. Biochem Biophys Res Commun. 1991;181:1572-9 pubmed
    ..Both forms are products of the gene infB with translational initiation at codon 1 (AUG) and codon 158 (GUG) in the same reading frame...
  42. Robertson E, Nicholson A. Phosphorylation of Escherichia coli translation initiation factors by the bacteriophage T7 protein kinase. Biochemistry. 1992;31:4822-7 pubmed
    ..These results provide the first evidence for the functional involvement of protein phosphorylation in the control of bacterial translation. ..
  43. Yoo J, RajBhandary U. Requirements for translation re-initiation in Escherichia coli: roles of initiator tRNA and initiation factors IF2 and IF3. Mol Microbiol. 2008;67:1012-26 pubmed publisher
    ..Strikingly, overexpression of IF3 also blocked E. coli from acting as a host for propagation of M13 phage. ..
  44. Vohlander Rasmussen L, Oliveira C, Pedersen J, Sperling Petersen H, Mortensen K. Structural transitions of translation initiation factor IF2 upon GDPNP and GDP binding in solution. Biochemistry. 2011;50:9779-87 pubmed publisher
    ..The structural transitions of IF2C upon GDPNP binding and following nucleotide hydrolysis support the concept of cofactor-dependent conformational switching rather than the classical model for GTPase activity. ..
  45. Caldas T, Laalami S, Richarme G. Chaperone properties of bacterial elongation factor EF-G and initiation factor IF2. J Biol Chem. 2000;275:855-60 pubmed
    ..These results suggest that EF-G and IF2, in addition to their role in translation, might be implicated in protein folding and protection from stress. ..
  46. Mortensen K, Hajnsdorf E, Regnier P, Sperling Petersen H. Improved recombinant tandem expression of translation initiation factor IF2 in RNASE E deficient E. coli cells. Biochem Biophys Res Commun. 1995;214:1254-9 pubmed
    ..gamma is dependent on or related to a posttranscriptional processing of the polycistronic nusA operon, containing infB, the gene for IF2...
  47. Laalami S, Putzer H, Plumbridge J, Grunberg Manago M. A severely truncated form of translational initiation factor 2 supports growth of Escherichia coli. J Mol Biol. 1991;220:335-49 pubmed
    ..strains carrying null mutations in the chromosomal copy of the gene for translational initiation factor (IF) 2 (infB)...
  48. Pon C, Paci M, Pawlik R, Gualerzi C. Structure-function relationship in Escherichia coli initiation factors. Biochemical and biophysical characterization of the interaction between IF-2 and guanosine nucleotides. J Biol Chem. 1985;260:8918-24 pubmed
    ..At low concentrations of IF-2 and 30 S subunits, GDP inhibits this reaction, acting as a strong competitive inhibitor of GTP (Ki = 1.25 X 10(-5)m) and preventing IF-2 from binding to the ribosomal subunit. ..
  49. Shiba K, Ito K, Nakamura Y, Dondon J, Grunberg Manago M. Altered translation initiation factor 2 in the cold-sensitive ssyG mutant affects protein export in Escherichia coli. EMBO J. 1986;5:3001-6 pubmed
    ..Now we show that the ssyG class of mutations are within infB coding for the translation initiation factor IF2...
  50. Ling C, Ermolenko D. Initiation factor 2 stabilizes the ribosome in a semirotated conformation. Proc Natl Acad Sci U S A. 2015;112:15874-9 pubmed publisher
    ..Our results suggest that positioning subunits in a semirotated orientation facilitates subunit association and support a model in which L1 stalk movement is coupled to intersubunit rotation and/or IF2 binding. ..
  51. Caserta E, Tomsic J, Spurio R, La Teana A, Pon C, Gualerzi C. Translation initiation factor IF2 interacts with the 30 S ribosomal subunit via two separate binding sites. J Mol Biol. 2006;362:787-99 pubmed
  52. Laursen B, Kjaergaard A, Mortensen K, Hoffman D, Sperling Petersen H. The N-terminal domain (IF2N) of bacterial translation initiation factor IF2 is connected to the conserved C-terminal domains by a flexible linker. Protein Sci. 2004;13:230-9 pubmed
    ..The features of structurally well-ordered N- and C-terminal domains connected by a flexible linker with significant helical content are reminiscent of another translation initiation factor, IF3. ..
  53. Laursen B, Siwanowicz I, Larigauderie G, Hedegaard J, Ito K, Nakamura Y, et al. Characterization of mutations in the GTP-binding domain of IF2 resulting in cold-sensitive growth of Escherichia coli. J Mol Biol. 2003;326:543-51 pubmed
    The infB gene encodes translation initiation factor IF2. We have determined the entire sequence of infB from two cold-sensitive Escherichia coli strains IQ489 and IQ490...
  54. Schmitt E, Guillon J, Meinnel T, Mechulam Y, Dardel F, Blanquet S. Molecular recognition governing the initiation of translation in Escherichia coli. A review. Biochimie. 1996;78:543-54 pubmed
    ..Finally, peptide deformylase and methionine aminopeptidase, which catalyze the amino terminal maturation of nascent polypeptides, can also be associated to the translation initiation process. ..
  55. Burakovskiĭ D, Smirnova A, Lesniak D, Kiparisov S, Leonov A, Sergiev P, et al. [Interaction of 23S ribosomal RNA helices 89 and 91 of Escherichia coli contributes to the activity of IF2 but is insignificant for elongation factors functioning]. Mol Biol (Mosk). 2007;41:1031-41 pubmed
    ..Thus, the contact between helices 89 and 91 is important for efficient IF2 functioning in translation initiation. ..
  56. Shiba K, Ito K, Yura T. Mutation that suppresses the protein export defect of the secY mutation and causes cold-sensitive growth of Escherichia coli. J Bacteriol. 1984;160:696-701 pubmed
    ..The gene ssyA was mapped at a new locus between hisS and glyA on the chromosome. It is possible that the product of this gene interacts both with the protein secretion system and the protein synthesizing system. ..
  57. Sacerdot C, Dessen P, Hershey J, Plumbridge J, Grunberg Manago M. Sequence of the initiation factor IF2 gene: unusual protein features and homologies with elongation factors. Proc Natl Acad Sci U S A. 1984;81:7787-91 pubmed
    The gene for protein synthesis initiation factor IF2 in Escherichia coli, infB, is located downstream from nusA on the same operon...