|Gene:||recX||Accession Numbers: EG12080 (EcoCyc), b2698, ECK2693|
RecX is an inhibitor of RecA. RecX interacts directly with RecA, inhibits its ssDNA-dependent ATPase, coprotease, and DNA strand exchange activities [Stohl03, Drees04], and blocks the extension of RecA filaments [Drees04a] or promotes RecA filament disassembly [Ragone08]. RecX itself has weak ssDNA binding activity [Drees04a]; functional competition between SSB and RecX suggest that an interaction of RecX with ssDNA may be part of the mechanism by which RecX inhibits RecA [Baitin08].
The interaction between RecX and RecA itself is modulated by other proteins. RecX competes directly with DinI, a positive modulator of RecA function, for binding to RecA [Lusetti04]. Both proteins modulate RecA-DNA structures, with dinI being epistatic to recX, wich is consistent with DinI acting upstream of RecX [Renzette07]. RecF protects nucleated RecA filaments from RecX inhibition [Lusetti06].
A structural model of RecX has been proposed, and its interaction with RecA [Mishra03] and ssDNA [Shvetsov14] was modeled. The interaction between RecX and RecA is modulated by the C-terminal domain of RecA and the concentration of free Mg2+ [Drees04, Renzette07]. A crystal structure of RecX from E. coli E24377A (99% sequence identity with the E. coli K-12 protein) has been solved at 1.8 Å resolution, showing a modular protein with repeated three-helix motifs. Site-directed mutagenesis of conserved basic residues on the concave side of RecX showed that they are important for repression of RecA activity in vitro [Ragone08].
Transcription of recX is regulated by LexA [Stohl03]. Expression is induced by DNA damage [Stohl03], nalidixic acid or mitomycin C [Van01]. Although recA and recX are cotranscribed, RecX is approximately 500 times less abundant than RecA. SOS transcriptional regulation and a translational regulation process each contribute to regulation of RecX abundance [Pages03].
Overproduction of RecX causes UV sensitivity and additional phenotypes that are consistent with RecA inhibition, such as defects in DNA damage induction of transcription and proteolysis of UmuD and LexA, and less P1 transduction compared to wild type [Stohl03]. Published reports differ as to whether there is a small [Stohl03, Renzette07] or no [Pages03] difference in UV sensitivity of a recX null mutant compared to wild type. A null mutation does not cause increased mutagenesis [Pages03], defects in DNA damage induction of transcription and proteolysis of UmuD and LexA [Stohl03], or defects in P1 transduction [Stohl03]. Overproduction of RecA is not lethal in a recX null mutant background, in contrast to the situation observed in other organisms [Pages03]. RecX does not appear to regulate transcription of recA [Pages03]. In wild-type cells, RecX itself does not appear to play a significant role in repression of SOS expression [Massoni12].
|Map Position: [2,820,161 <- 2,820,661] (60.78 centisomes)||Length: 501 bp / 166 aa|
Molecular Weight of Polypeptide: 19.424 kD (from nucleotide sequence), 19.274 kD (experimental) [Drees04 ]
Unification Links: ASAP:ABE-0008872 , DIP:DIP-10410N , EchoBASE:EB2005 , EcoGene:EG12080 , EcoliWiki:b2698 , OU-Microarray:b2698 , PortEco:recX , PR:PRO_000023709 , Protein Model Portal:P33596 , RefSeq:NP_417178 , RegulonDB:EG12080 , SMR:P33596 , String:511145.b2698 , UniProt:P33596
|Biological Process:||GO:0006974 - cellular response to DNA damage stimulus
GO:0009432 - SOS response [UniProtGOA11a, Stohl03]
GO:0043086 - negative regulation of catalytic activity [Stohl03]
GO:0006281 - DNA repair [UniProtGOA11a]
GO:0006282 - regulation of DNA repair [GOA01a]
|Molecular Function:||GO:0005515 - protein binding
GO:0019899 - enzyme binding [Stohl03]
|Cellular Component:||GO:0005737 - cytoplasm
GO:0005829 - cytosol [DiazMejia09]
|MultiFun Terms:||cell processes → protection → radiation|
|cell processes → SOS response|
|information transfer → DNA related → DNA recombination|
|information transfer → DNA related → DNA repair|
|regulation → type of regulation → posttranscriptional → inhibition / activation of enzymes|
|Growth Medium||Growth?||T (°C)||O2||pH||Osm/L||Growth Observations|
|LB enriched||Yes||37||Aerobic||6.95||Yes [Gerdes03, Comment 1]|
|LB Lennox||Yes||37||Aerobic||7||Yes [Baba06, Comment 2]|
|M9 medium with 1% glycerol||Yes||37||Aerobic||7.2||0.35||Yes [Joyce06, Comment 3]|
|MOPS medium with 0.4% glucose||Yes||37||Aerobic||7.2||0.22||Yes [Baba06, Comment 2]|
10/20/97 Gene b2698 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG12080; 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
Bakhlanova10: Bakhlanova IV, Dudkina AV, Baitin DM, Knight KL, Cox MM, Lanzov VA (2010). "Modulating cellular recombination potential through alterations in RecA structure and regulation." Mol Microbiol 78(6);1523-38. PMID: 21143322
De94: De Mot R, Schoofs G, Vanderleyden J (1994). "A putative regulatory gene downstream of recA is conserved in gram-negative and gram-positive bacteria." Nucleic Acids Res 22(7);1313-4. PMID: 8165147
DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114
Drees04: Drees JC, Lusetti SL, Cox MM (2004). "Inhibition of RecA protein by the Escherichia coli RecX protein: modulation by the RecA C terminus and filament functional state." J Biol Chem 279(51);52991-7. PMID: 15466870
Dudkina: Dudkina AV, Shvetsov AV, Bakhlanova IV, Baitin DM "[Changing of filamentation dynamics of RecA protein, induced by D112R amino acid substitution or ATP to dATP replacement, results in filament steadiness TO THE RecX protein action]." Mol Biol (Mosk) 45(3);546-53. PMID: 21790018
Gerdes03: Gerdes SY, Scholle MD, Campbell JW, Balazsi G, Ravasz E, Daugherty MD, Somera AL, Kyrpides NC, Anderson I, Gelfand MS, Bhattacharya A, Kapatral V, D'Souza M, Baev MV, Grechkin Y, Mseeh F, Fonstein MY, Overbeek R, Barabasi AL, Oltvai ZN, Osterman AL (2003). "Experimental determination and system level analysis of essential genes in Escherichia coli MG1655." J Bacteriol 185(19);5673-84. PMID: 13129938
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
Long08a: Long JE, Renzette N, Centore RC, Sandler SJ (2008). "Differential requirements of two recA mutants for constitutive SOS expression in Escherichia coli K-12." PLoS One 3(12);e4100. PMID: 19116657
Long09a: Long JE, Renzette N, Sandler SJ (2009). "Suppression of constitutive SOS expression by recA4162 (I298V) and recA4164 (L126V) requires UvrD and RecX in Escherichia coli K-12." Mol Microbiol 73(2);226-39. PMID: 19555451
Lusetti06: Lusetti SL, Hobbs MD, Stohl EA, Chitteni-Pattu S, Inman RB, Seifert HS, Cox MM (2006). "The RecF protein antagonizes RecX function via direct interaction." Mol Cell 21(1);41-50. PMID: 16387652
Moore12: Moore JM, Wimberly H, Thornton PC, Rosenberg SM, Hastings PJ (2012). "Gross chromosomal rearrangement mediated by DNA replication in stressed cells: evidence from Escherichia coli." Ann N Y Acad Sci 1267;103-9. PMID: 22954223
Rajagopala14: Rajagopala SV, Sikorski P, Kumar A, Mosca R, Vlasblom J, Arnold R, Franca-Koh J, Pakala SB, Phanse S, Ceol A, Hauser R, Siszler G, Wuchty S, Emili A, Babu M, Aloy P, Pieper R, Uetz P (2014). "The binary protein-protein interaction landscape of Escherichia coli." Nat Biotechnol 32(3);285-90. PMID: 24561554
Shvetsov14: Shvetsov AV, Lebedev DV, Chervyakova DB, Bakhlanova IV, Yung IA, Radulescu A, Kuklin AI, Baitin DM, Isaev-Ivanov VV (2014). "Structure of RecX protein complex with the presynaptic RecA filament: Molecular dynamics simulations and small angle neutron scattering." FEBS Lett 588(6);948-55. PMID: 24530684
Stohl02: Stohl EA, Blount L, Seifert HS (2002). "Differential cross-complementation patterns of Escherichia coli and Neisseria gonorrhoeae RecA proteins." Microbiology 2002;148(Pt 6);1821-31. PMID: 12055302
Stohl03: Stohl EA, Brockman JP, Burkle KL, Morimatsu K, Kowalczykowski SC, Seifert HS (2003). "Escherichia coli RecX inhibits RecA recombinase and coprotease activities in vitro and in vivo." J Biol Chem 2003;278(4);2278-85. PMID: 12427742
Van01: Van Dyk TK, DeRose EJ, Gonye GE (2001). "LuxArray, a high-density, genomewide transcription analysis of Escherichia coli using bioluminescent reporter strains." J Bacteriol 183(19);5496-505. PMID: 11544210
Venkatesh02: Venkatesh R, Ganesh N, Guhan N, Reddy MS, Chandrasekhar T, Muniyappa K (2002). "RecX protein abrogates ATP hydrolysis and strand exchange promoted by RecA: insights into negative regulation of homologous recombination." Proc Natl Acad Sci U S A 2002;99(19);12091-6. PMID: 12218174
Zaitsev94: Zaitsev E, Alexseyev A, Lanzov V, Satin L, Clark AJ (1994). "Nucleotide sequence between recA and alaSp in E. coli K12 and the sequence change in four recA mutations." Mutat Res 1994;323(4);173-7. PMID: 7512687
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