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Escherichia coli K-12 substr. MG1655 Polypeptide: YajC

Gene: yajC Accession Numbers: EG11096 (EcoCyc), b0407, ECK0401

Regulation Summary Diagram: ?

Regulation summary diagram for yajC

Component of:
SecD-SecF-YajC-YidC Secretion Complex (extended summary available)
Sec Holo-Translocon (extended summary available)

YajC is a member of the SecD/SecF/YajC/YidC complex, which functions in concert with SecYEG to stabilize the insertion of SecA and its bound preprotein into the inner membrane. Under conditions of over production YajC forms a complex with both SecYEG and SecDF [Nouwen02]. YajC is not essential for cell viability or protein export [Taura94, Pogliano94a]. Membrane topology experiments indicate that the C-terminus of YajC is located in the cytoplasm and the N-terminus is buried in the membrane [Fang11]. When purifed and expressed the C-terminal portion of YajC exists as a trimer and forms a structure rich in β-strands [Fang11].

Citations: [Duong97b, Duong97a, Scotti00, Muller01, Nouwen01, Kato03]

Locations: inner membrane

Map Position: [426,511 -> 426,843] (9.19 centisomes, 33°)
Length: 333 bp / 110 aa

Molecular Weight of Polypeptide: 11.887 kD (from nucleotide sequence)

Unification Links: ASAP:ABE-0001415 , DIP:DIP-29531N , EchoBASE:EB1088 , EcoGene:EG11096 , EcoliWiki:b0407 , OU-Microarray:b0407 , PortEco:yajC , Pride:P0ADZ7 , Protein Model Portal:P0ADZ7 , RefSeq:NP_414941 , RegulonDB:EG11096 , SMR:P0ADZ7 , String:511145.b0407 , UniProt:P0ADZ7

Relationship Links: InterPro:IN-FAMILY:IPR003849 , PDB:Structure:2RDD , Pfam:IN-FAMILY:PF02699 , Prints:IN-FAMILY:PR01853

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

GO Terms:

Cellular Component: GO:0005887 - integral component of plasma membrane Inferred from experiment [Fang11]
GO:0031522 - cell envelope Sec protein transport complex Inferred from experiment [Duong97b]
GO:0005886 - plasma membrane Inferred by computational analysis [UniProtGOA11, UniProtGOA11a]
GO:0016020 - membrane Inferred by computational analysis [UniProtGOA11a]
GO:0016021 - integral component of membrane Inferred by computational analysis [UniProtGOA11a]

MultiFun Terms: cell structure membrane
transport Channel-type Transporters Pyrophosphate Bond (ATP; GTP; P2) Hydrolysis-driven Active Transporters The Type II (General) Secretory Pathway (IISP) Family

Essentiality data for yajC knockouts: ?

Growth Medium Growth? T (°C) O2 pH Osm/L Growth Observations
LB Lennox Yes 37 Aerobic 7   Yes [Baba06, Comment 1]
M9 medium with 1% glycerol Yes 37 Aerobic 7.2 0.35 Yes [Joyce06, Comment 2]
MOPS medium with 0.4% glucose Yes 37 Aerobic 7.2 0.22 Yes [Baba06, Comment 1]

Subunit of: SecD-SecF-YajC-YidC Secretion Complex

Subunit composition of SecD-SecF-YajC-YidC Secretion Complex = [YidC][YajC][SecF][SecD]
         inner-membrane protein insertion factor = YidC (extended summary available)

Component of: Sec Holo-Translocon (extended summary available)

SecD/SecF/YajC and YidC are all components of the Sec protein secretion pathway. They are believed to work in conjunction with SecYEG to stabilize the insertion of SecA and its bound preprotein into the inner membrane.

In studies of conditional lethal mutations of secD and secF genes, secA transcription was found to be stimulated due to severe general protein translocation defects. Deletions of secD result in cold-sensitive mutations which could be complemented by plasmids containing the gene [Gardel87]. Overexpression of SecD and SecF increases translocation in wild-type cells [Pogliano94]. Within the same operon as secD and secF is a third gene known as yajC which may also have a role in protein translocation [Pogliano94a]. Co-purification studies [Samuelson00] indicate that YidC is associated with the SecYEG translocase complex and plays a role in the assembly of inner membrane proteins. Subsequent studies [Nouwen02] show that, under conditions of SecD/SecF/YajC overproduction, YidC forms a heterotetrameric complex with SecD/SecF/YajC.

In vitro reconstitution studies demonstrated that the presence of SecD/SecF/YajC stabilizes the SecA insertion complex and inhibits movement of the SecA bound precursor in either direction [Duong97a]. If this model holds true, then the SecD/SecF/YajC/YidC stabilization complex must be released from the SecYEG complex or be otherwise inactivated in order for SecA to de-insert from the complex and to begin another round of stepwise translocation powered by ATP hydrolysis [Danese98].

Subunit of: Sec Holo-Translocon

Synonyms: Sec translocation complex

Subunit composition of Sec Holo-Translocon = [(YidC)(YajC)(SecF)(SecD)][(SecE)(SecG)(SecY)]
         SecD-SecF-YajC-YidC Secretion Complex = (YidC)(YajC)(SecF)(SecD) (extended summary available)
                 inner-membrane protein insertion factor = YidC (extended summary available)
         SecYEG translocase = (SecE)(SecG)(SecY) (extended summary available)

The Sec 'holo-translocon' (HTL) is a large multisubunit complex that mediates the transport of nascent polypeptides across, or their integration into, the cytoplasmic membrane. The holo-translocon is a seven subunit complex containing an inner membrane heterotrimeric SecYEG complex that forms the protein conducting channel plus an ancillary complex, SecDFYajC and the Yid C membrane protein, both of which interact with SecYEG to enhance protein transport or integration. The energy for protein translocation is provided by the motor protein ATPase SecA and the proton motive force. The HTL complex is less effective in ATP-dependent SecA-driven protein secretion and more dependent on the PMF [Schulze14].

Simultaneous overexpression of all 7 subunits of the sec HTL facilitates purification and isolation of a complex that is competent for protein secretion and for membrane protein insertion in vitro. The complex contains one copy of SecYEG, one copy of SecDFYajC and one copy of YidC. The HTL associates preferentially with ribosomes displaying nascent peptide. Protein translocation in HTL containing proteoliposomes is stimulated by cardiolipin and by the PMF [Schulze14].

Two pathways of protein translocation converge at the Sec translocon. In the posttranslational pathway the newly synthesised polypeptide is bound by SecB, a cytosolic chaperone which aids targeting to the membrane and maintains a translocation competent conformation of the pre-protein, while in the co-translational pathway the SRP complex binds to the nascent protein as it emerges from the ribosome and the SRP/ribosome/protein complex is then targeted to the Sec translocase.

An experimental approach using alkaline phosphatase (PhoA) fusions to protein signal sequences has allowed discrimination between the major modes of transport, including the Sec protein translocase, across the inner membrane [Marrichi08].

Reviews: [Lycklama12, duPlessis11, Driessen08, Driessen98, deKeyzer03, Manting00, Gold07].
Comments: [Duong14]

Citations: [Ojemalm13]

Molecular Weight: 250.0 kD (experimental) [Schulze14]

GO Terms:

Biological Process: GO:0043952 - protein transport by the Sec complex Inferred from experiment [Schulze14]
GO:0065002 - intracellular protein transmembrane transport Inferred from experiment [Schulze14]
Molecular Function: GO:0009977 - proton motive force dependent protein transmembrane transporter activity Inferred from experiment [Schulze14]
GO:0015462 - protein-transmembrane transporting ATPase activity Inferred from experiment [Schulze14]
Cellular Component: GO:0031522 - cell envelope Sec protein transport complex Inferred from experiment [Schulze14]

Last-Curated ? 06-Jul-2014 by Mackie A , Macquarie University

Sequence Features

Protein sequence of YajC with features indicated

Feature Class Location Citations Comment
Transmembrane-Region 19 -> 39
UniProt: Helical;; Non-Experimental Qualifier: potential;
Sequence-Conflict 82
[Gardel90, UniProt10a]
UniProt: (in Ref. 1; CAA39633);

Gene Local Context (not to scale): ?

Gene local context diagram

Transcription Units:

Transcription-unit diagram

Transcription-unit diagram


10/20/97 Gene b0407 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG11096; confirmed by SwissProt match.


Baba06: Baba T, Ara T, Hasegawa M, Takai Y, Okumura Y, Baba M, Datsenko KA, Tomita M, Wanner BL, Mori H (2006). "Construction of Escherichia coli K-12 in-frame, single-gene knockout mutants: the Keio collection." Mol Syst Biol 2;2006.0008. PMID: 16738554

Danese98: Danese PN, Silhavy TJ (1998). "Targeting and assembly of periplasmic and outer-membrane proteins in Escherichia coli." Annu Rev Genet 32;59-94. PMID: 9928475

deKeyzer03: de Keyzer J, van der Does C, Driessen AJ (2003). "The bacterial translocase: a dynamic protein channel complex." Cell Mol Life Sci 60(10);2034-52. PMID: 14618254

Driessen08: Driessen AJ, Nouwen N (2008). "Protein translocation across the bacterial cytoplasmic membrane." Annu Rev Biochem 77;643-67. PMID: 18078384

Driessen98: Driessen AJ, Fekkes P, van der Wolk JP (1998). "The Sec system." Curr Opin Microbiol 1(2);216-22. PMID: 10066476

Duong14: Duong F (2014). "Capturing the bacterial holo-complex." Proc Natl Acad Sci U S A 111(13);4739-40. PMID: 24707040

Duong97a: Duong F, Wickner W (1997). "The SecDFyajC domain of preprotein translocase controls preprotein movement by regulating SecA membrane cycling." EMBO J 16(16);4871-9. PMID: 9305629

Duong97b: Duong F, Wickner W (1997). "Distinct catalytic roles of the SecYE, SecG and SecDFyajC subunits of preprotein translocase holoenzyme." EMBO J 16(10);2756-68. PMID: 9184221

duPlessis11: du Plessis DJ, Nouwen N, Driessen AJ (2011). "The Sec translocase." Biochim Biophys Acta 1808(3);851-65. PMID: 20801097

Fang11: Fang J, Wei Y (2011). "Expression, purification and characterization of the Escherichia coli integral membrane protein YajC." Protein Pept Lett 18(6);601-8. PMID: 21235483

Gardel87: Gardel C, Benson S, Hunt J, Michaelis S, Beckwith J (1987). "secD, a new gene involved in protein export in Escherichia coli." J Bacteriol 169(3);1286-90. PMID: 3029032

Gardel90: Gardel C, Johnson K, Jacq A, Beckwith J (1990). "The secD locus of E.coli codes for two membrane proteins required for protein export." EMBO J 9(10);3209-16. PMID: 2170107

Gold07: Gold VA, Duong F, Collinson I (2007). "Structure and function of the bacterial Sec translocon." Mol Membr Biol 24(5-6);387-94. PMID: 17710643

Joyce06: Joyce AR, Reed JL, White A, Edwards R, Osterman A, Baba T, Mori H, Lesely SA, Palsson BO, Agarwalla S (2006). "Experimental and computational assessment of conditionally essential genes in Escherichia coli." J Bacteriol 188(23);8259-71. PMID: 17012394

Kato03: Kato Y, Nishiyama K, Tokuda H (2003). "Depletion of SecDF-YajC causes a decrease in the level of SecG: implication for their functional interaction." FEBS Lett 550(1-3);114-8. PMID: 12935896

Lycklama12: Lycklama A Nijeholt JA, Driessen AJ (2012). "The bacterial Sec-translocase: structure and mechanism." Philos Trans R Soc Lond B Biol Sci 367(1592);1016-28. PMID: 22411975

Manting00: Manting EH, Driessen AJ (2000). "Escherichia coli translocase: the unravelling of a molecular machine." Mol Microbiol 37(2);226-38. PMID: 10931320

Marrichi08: Marrichi MJ, Camacho L, Russell DG, Delisa MP (2008). "Genetic toggling of alkaline phosphatase folding reveals signal peptides for all major modes of transport across the inner membrane of bacteria." J Biol Chem 283(50):35223-35. PMID: 18819916

Muller01: Muller M, Koch HG, Beck K, Schafer U (2001). "Protein traffic in bacteria: multiple routes from the ribosome to and across the membrane." Prog Nucleic Acid Res Mol Biol 66;107-57. PMID: 11051763

Nouwen01: Nouwen N, van der Laan M, Driessen AJ (2001). "SecDFyajC is not required for the maintenance of the proton motive force." FEBS Lett 508(1);103-6. PMID: 11707277

Nouwen02: Nouwen N, Driessen AJ (2002). "SecDFyajC forms a heterotetrameric complex with YidC." Mol Microbiol 44(5);1397-405. PMID: 12068816

Ojemalm13: Ojemalm K, Botelho SC, Studle C, von Heijne G (2013). "Quantitative analysis of SecYEG-mediated insertion of transmembrane α-helices into the bacterial inner membrane." J Mol Biol 425(15);2813-22. PMID: 23659793

Pogliano94: Pogliano JA, Beckwith J (1994). "SecD and SecF facilitate protein export in Escherichia coli." EMBO J 13(3);554-61. PMID: 8313900

Pogliano94a: Pogliano KJ, Beckwith J (1994). "Genetic and molecular characterization of the Escherichia coli secD operon and its products." J Bacteriol 176(3);804-14. PMID: 7507921

Samuelson00: Samuelson JC, Chen M, Jiang F, Moller I, Wiedmann M, Kuhn A, Phillips GJ, Dalbey RE (2000). "YidC mediates membrane protein insertion in bacteria." Nature 406(6796);637-41. PMID: 10949305

Schulze14: Schulze RJ, Komar J, Botte M, Allen WJ, Whitehouse S, Gold VA, Lycklama A Nijeholt JA, Huard K, Berger I, Schaffitzel C, Collinson I (2014). "Membrane protein insertion and proton-motive-force-dependent secretion through the bacterial holo-translocon SecYEG-SecDF-YajC-YidC." Proc Natl Acad Sci U S A 111(13);4844-9. PMID: 24550475

Scotti00: Scotti PA, Urbanus ML, Brunner J, de Gier JW, von Heijne G, van der Does C, Driessen AJ, Oudega B, Luirink J (2000). "YidC, the Escherichia coli homologue of mitochondrial Oxa1p, is a component of the Sec translocase." EMBO J 19(4);542-9. PMID: 10675323

Taura94: Taura T, Akiyama Y, Ito K (1994). "Genetic analysis of SecY: additional export-defective mutations and factors affecting their phenotypes." Mol Gen Genet 243(3);261-9. PMID: 8190079

UniProt10: UniProt Consortium (2010). "UniProt version 2010-07 released on 2010-06-15 00:00:00." Database.

UniProt10a: UniProt Consortium (2010). "UniProt version 2010-11 released on 2010-11-02 00:00:00." Database.

UniProtGOA11: UniProt-GOA (2011). "Gene Ontology annotation based on the manual assignment of UniProtKB Subcellular Location terms in UniProtKB/Swiss-Prot entries."

UniProtGOA11a: UniProt-GOA (2011). "Gene Ontology annotation based on manual assignment of UniProtKB keywords in UniProtKB/Swiss-Prot entries."

Other References Related to Gene Regulation

Reuter91: Reuter K, Slany R, Ullrich F, Kersten H (1991). "Structure and organization of Escherichia coli genes involved in biosynthesis of the deazaguanine derivative queuine, a nutrient factor for eukaryotes." J Bacteriol 173(7);2256-64. PMID: 1706703

Salmon03: Salmon K, Hung SP, Mekjian K, Baldi P, Hatfield GW, Gunsalus RP (2003). "Global gene expression profiling in Escherichia coli K12. The effects of oxygen availability and FNR." J Biol Chem 278(32);29837-55. PMID: 12754220

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of EcoCyc: Nucleic Acids Research 41:D605-12 2013
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