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Schematic diagram of bacterial conjugation. 1 - Donor cell produces pilus. 2 - Pilus attaches to recipient cell, brings the two cells together. 3 - The mobile plasmid is nicked and a single strand of DNA is then transferred to the recipient cell. 4 - Both cells recircularize their plasmids, synthesize second strands, and reproduce pili; both cells are now viable donors. Image courtesy of [ Wikipedia]

Bacterial conjugation is the transfer of genetic material between two bacterial cell via direct cell-to-cell contact. Although often incorrectly characterized as the bacterial equivalent of mating, in fact it is simply the transfer of genetic material from a donor cell to a recipient cell. Bacterial conjugation is also known as a "type IV secretion system".

This behaviour is characterized by the presence of a specialized plasmid (small, circular piece of transferrable DNA most often found within bacteria) known as a conjugative plasmid. The conjugative plasmid holds a distinct and specialized set of coding regions including the following

  • OriT (Origin of Transfer): Unlike other plasmids, the conjugative plasmid has its own origin of transfer nic region. This is a specialized portion of the genome where one of the two strands of the circular plasmid DNA is cut to allow for rolling circle replication of the plasmid containing the OriT region into a recipient cell. During rolling circle replication, the cut end of one strand is inserted into the recipient cell while recipient polymerases construct the complementary strand back into a circular piece of DNA.
  • TraJ (Transfer genes): The activation of this gene sets off a cascade of other plasmid genes (and thus corresponding protein expressions) which act in concert to form "mating" characteristics in the host bacterial cell. Such salient characteristics include:
    • growth of a pilus--a long whip-like apparatus used to hook the two cells together
    • fusion of the outer membranes to allow for transfer of genetic material
    • formation of "surface exclusion proteins" which prevents the cell containing the conjugative plasmid from mating with other conjugative plasmids of its type

Two of the most well-studied and characterized types of conjugative plasmids are types "F" (from the F plasmid) and "R". The employed nomenclature for conjugative plasmid genes is the gene name first with the type afterwards. For example, the "TraJr" or "TraJR" gene denotes the "TraJ" gene of the "R" type conjugative plasmid.

Note it was previously believed that transfer of genetic material occurred via the pilus itself; now, most think that the transfer of genetic material occurs via a separate direct channel between the two cells.

BBa_I714000ConjugationR388 oriT ( transfer origin of E.coli IncW group R388 plasmid)402
BBa_I714003Conjugationminimum oriT of plasmid R64 ( origin of transfer, R64 is IncI-1 )83
BBa_I714030ConjugationOriT-F (Origin of Transfer for the F-plasmid nic region)355
BBa_I714031ConjugationOriT-R (Origin of Transfer for the R751-plasmid nic region) 278
BBa_I714032ConjugationOriT-S (Origin of Transfer for the pSC101-plasmid nic region) 131
BBa_J01000CodingTraJF controls conjugative transfer in F plasmid690
BBa_J01001CodingTraJr protein (controls conjugative transfer in RP4 plasmid)378
BBa_J01002ConjugationOriT-F (Origin of Transfer for the F-plasmid nic region)365
BBa_J01003ConjugationOriT-R (Origin of transfer for the R-plasmid nic region)371
BBa_J01077PlasmidF plasmid (x-OriT, x-TraJ) 
BBa_J01078PlasmidR plasmid (x-OriT, x-TraJ) 
BBa_J107185ConjugationoriT from RK2354
BBa_J23046Conjugationput in later - SIL strain 
BBa_K1053123ConjugationSplit EYFP N-terminal domain fused with HTLV-1 Rex peptide606
BBa_K1053124ConjugationSplit EYFP C-terminal domain fused with λN peptide297
BBa_K109550CodingBacterial conjugative regulator KorA306
BBa_K109551CodingTrbA transcription factor for the Tra2 operon in incP alpha conjugation366
BBa_K125320ConjugationOriT-RP4 (Origin of transfer for the RP4 plasmid)99
BBa_K125350ConjugationoriTr with lac promoter and lacZ979
BBa_K125360ConjugationoriT with lac promoter and lacZ707
BBa_K1439000ConjugationOrigin of transfer for the RP4-plasmid nic region.350
BBa_K1510119ConjugationA truncated INPNC anchor protein that binds fragments on the cell surface1564
BBa_K1510214ConjugationDispersin generator circuit2053
BBa_K1510409ConjugationA Steptococcus Mutants adhesive complex.1780
BBa_K1510603ConjugationDispersin generator ,with constitutive promoter plus yebf1916
BBa_K1510624ConjugationTruncated lysostaphin coding sequence plus strong promoter and yebf1331
BBa_K1510816ConjugationA Steptococcus Mutants adhesive complex.1651
BBa_K1510831ConjugationFragrance generator part2: alcohol acetyltransferase I and RBS1599
BBa_K1510904ConjugationTruncated lysostaphin coding circuit1468
BBa_K1510915Conjugation ketoisocaproate decarboxylase (THI3) Circuit1985
BBa_K1510922ConjugationFragrance generator part1: ketoisocaproate decarboxylase (THI3) and RBS1848
BBa_K1510925ConjugationFragrance generator3: branched-chain amino acid transaminase (BAT2) and RBS1152
BBa_K1682014ConjugationConjugation(RP4) plasmid with partial GFP1395
BBa_K175000CodingtrbC (pilin) of IncP beta R751 plasmid468
BBa_K175001CodingtrbK (entry exclusion) of IncP beta R751 plasmid231
BBa_K2144101Plasmid_BackboneVector containing Hisx6 and Sortase tag LPETGG2117
BBa_K2657002ConjugationRp4 Origin of Transfer PhytoBrick131
BBa_K2759003ConjugationBacterioferritin (BFR) with sfGFP conjugation1203
BBa_K2791011ConjugationTranslational coupling device, weak.32
BBa_K2791012ConjugationTranslational coupling device, strong.32
BBa_K2791013ConjugationTranslational coupling device, medium.32
BBa_K2791014ConjugationTranslational coupling device, very weak.32
BBa_K2913002ConjugationA conjugation between Pluc anad HucO 11
BBa_K2913008ConjugationA referenced conjugation between Pluc and CDS sequence35
BBa_K2961003ConjugationgRNA / crRNA fixed-loop repeat for Cpf1 / Cas12a21
BBa_K2976010ConjugationImproved T2A63
BBa_K2976011Conjugation(Gly4Ser)3 linker30
BBa_K2976012ConjugationGly-Ser-Ser linker9
BBa_K3819025ConjugationPro/Thr-rich Linker108
BBa_K3875021ConjugationCas9 binding34
BBa_K3946006ConjugationL2NC silica tag+term (CT)4461
BBa_K3946007ConjugationL2NC+linker+term (CT)4516
BBa_K3946044ConjugationSb7 silica tag (C)-PETase (W159H/ S238F)902
BBa_K3946045ConjugationSb7 silica tag (C)-LCC-WCCG variant811
BBa_K4103001ConjugationpIP501 transfer origin378
BBa_K4170009ConjugationSerine-serine-glycine flexible linker9
BBa_K4580004ConjugationNdmB-6x his-GFP1806
BBa_K4587106ConjugationGS linker48
BBa_K4643003ConjugationincP origin of transfer109
BBa_K4765023RNAPmeI linker27
BBa_K4971011ConjugationLinker protein sequence with starting codon30
BBa_K543016ConjugationBacteriophage Lysis Cassette S105, R, and Rz under Tet promoter (conjugative)1838
BBa_K543030Conjugation[I714030][J23066][I714030] (Constitutive expression)1105
BBa_K543032Conjugationassay system of killing by conjugation3615
BBa_K640002ConjugationoriT - Interspecies origin of transfer260
BBa_K640004ConjugationDevice for conjugation of plasmids from E. coli to pseudomonas642
BBa_K640005ConjugationDevice for conjugating plasmids from E. coli to pseudomonas753
BBa_K808028SignallingPhoA: signal sequence for peri plasmic expression63
BBa_K873003Conjugationconjugative transfer of RFG1302

YifanYangPhoto.jpg MingzhiQuPhoto.jpg Yifan Yang, Mingzhi Qu and the 2007 Peking Yniveristy iGEM team designed the parts BBa_I714000, BBa_I714003, BBa_I714030, BBa_I714031 and BBa_I714032. IGEM2005group.jpg The 2005 Berkeley iGEM team designed the parts BBa_J01000-BBa_J01003 and BBa_J01077-BBa_J01078.
JCA Photo.png Chris Anderson and the 2006 Berkeley iGEM team design the parts BBa_J23046. IngridSwansonPhoto.jpg Ingrid Swanson and the 2008 University of Washington iGEM team designed the parts BBa_K109550 and BBa_K109551. MargaretRuzickiPhoto.jpg Margaret Ruzicki and the 2008 University of Hawaii iGEM team designed the parts Part:BBa_K125320, Part:BBa_K125350, and Part:BBa_K125360.



  1. Frost pmid=7915817
  2. Jaenecke pmid=8858584
  3. Lawley pmid=12855161
  4. Lessl pmid=8407818
  5. Miller pmid=2993231
  6. Martinez-Morales pmid=10559184
  7. Wilkins pmid=12220405


  • [ Wikipedia entry on Bacterial Conjugation]
  • 2005 UC Berkeley iGEM team [ project] and [ protocols]