|Gene:||xseA||Accession Numbers: EG11072 (EcoCyc), b2509, ECK2505|
Component of: exonuclease VII (extended summary available)
XseA is the large subunit of Exonuclease VII [Vales82].
|Map Position: [2,632,254 -> 2,633,624] (56.73 centisomes)||Length: 1371 bp / 456 aa|
Molecular Weight of Polypeptide: 51.832 kD (from nucleotide sequence), 54 kD (experimental) [Vales82 ]
Unification Links: ASAP:ABE-0008263 , CGSC:6 , DIP:DIP-11146N , EchoBASE:EB1065 , EcoGene:EG11072 , EcoliWiki:b2509 , Mint:MINT-1272208 , OU-Microarray:b2509 , PortEco:xseA , PR:PRO_000024237 , Pride:P04994 , Protein Model Portal:P04994 , RefSeq:NP_417004 , RegulonDB:EG11072 , String:511145.b2509 , UniProt:P04994
|Biological Process:||GO:0000738 - DNA catabolic process, exonucleolytic
[GOA06, GOA01, GOA01a]
GO:0006308 - DNA catabolic process [GOA01a]
GO:0090305 - nucleic acid phosphodiester bond hydrolysis [UniProtGOA11a]
|Molecular Function:||GO:0005515 - protein binding
GO:0003676 - nucleic acid binding [GOA01a]
GO:0004518 - nuclease activity [UniProtGOA11a]
GO:0004527 - exonuclease activity [UniProtGOA11a]
GO:0008855 - exodeoxyribonuclease VII activity [GOA06, GOA01, GOA01a]
GO:0016787 - hydrolase activity [UniProtGOA11a]
|Cellular Component:||GO:0005737 - cytoplasm
[UniProtGOA11, UniProtGOA11a, GOA06]
GO:0005829 - cytosol [DiazMejia09]
GO:0009318 - exodeoxyribonuclease VII complex [GOA01a]
|MultiFun Terms:||information transfer → DNA related → DNA degradation|
|metabolism → degradation of macromolecules → DNA|
|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]|
Subunit of: exonuclease VII
Purified Exonuclease VII (ExoVII) has been shown to be specific for single-stranded, linear DNA or duplex DNA with single-stranded termini [Chase74]. ExoVII can initiate hydrolysis at either 5` or 3` ends of DNA with oligonucleotides generated as products [Chase74]. Large oligonucleotides are generated first, and these can be further degraded to smaller oligonucleotides [Chase74a]. ExoVII activity is ATP-independent [Chase74a]. ExoVII is also capable of excision of thymine dimers from duplex DNA after incision by an endonuclease specific for thymine dimers [Chase74a]. ExoVII activity remains high in the presence of EDTA, is increased by Mg2+, and is optimum at a pH of 7.9 in phosphate buffer [Chase74]. The friction coefficient of ExoVII suggests an asymmetric protein structure [Chase74].
Mutants deficient in RecJ, exonuclease I, and exonuclease VII are unusually sensitive to UV irradiation [Viswanathan99]. XseA mutants have increased frequency of recombination and sensitivity to nalidixic acid [Chase77] as well as reduced survivability at elevated temperatures in a polAex- background [Chase77a]. Exonuclease VII has been purified and was found to be composed of 1 subunit of XseA of 54 kDa and 4 subunits of XseB of 10.5 kDa [Vales82]. Overproduction of XseA reduced exonuclease VII acitivity [Chase86]. xseA transcription is repressed when the divergently transcribed guaBA is induced by the cyclic AMP receptor protein [Hutchings00].
Molecular Weight: 88 kD (experimental) [Chase74]
|Biological Process:||GO:0000738 - DNA catabolic process, exonucleolytic [Chase74a]|
|Molecular Function:||GO:0008297 - single-stranded DNA exodeoxyribonuclease activity [Chase74]|
Enzymatic reaction of: exonuclease VII
EC Number: 126.96.36.199
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
The reaction is physiologically favored in the direction shown.
10/20/97 Gene b2509 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG11072; 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
Butland05: Butland G, Peregrin-Alvarez JM, Li J, Yang W, Yang X, Canadien V, Starostine A, Richards D, Beattie B, Krogan N, Davey M, Parkinson J, Greenblatt J, Emili A (2005). "Interaction network containing conserved and essential protein complexes in Escherichia coli." Nature 433(7025);531-7. PMID: 15690043
Chase77a: Chase JW, Masker WE (1977). "Deoxyribonucleic acid repair in Escherichia coli mutants deficient in the 5'----3' exonuclease activity of deoxyribonucleic acid polymerase I and exonuclease VII." J Bacteriol 130(2);667-75. PMID: 400786
Chase86: Chase JW, Rabin BA, Murphy JB, Stone KL, Williams KR (1986). "Escherichia coli exonuclease VII. Cloning and sequencing of the gene encoding the large subunit (xseA)." J Biol Chem 261(32);14929-35. PMID: 3021756
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
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
Hutchings00: Hutchings MI, Drabble WT (2000). "Regulation of the divergent guaBA and xseA promoters of Escherichia coli by the cyclic AMP receptor protein." FEMS Microbiol Lett 187(2);115-22. PMID: 10856643
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
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
Viswanathan99: Viswanathan M, Lanjuin A, Lovett ST (1999). "Identification of RNase T as a high-copy suppressor of the UV sensitivity associated with single-strand DNA exonuclease deficiency in Escherichia coli." Genetics 151(3);929-34. PMID: 10049912
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