|Gene:||hsdS||Accession Numbers: EG10460 (EcoCyc), b4348, ECK4338|
Synonyms: hsp, hss, rm
Component of: EcoKI restriction-modification system (extended summary available)
HsdS is the specificity-determining component of the EcoKI restriction-modification system [Sain80].
|Map Position: [4,578,091 <- 4,579,485] (98.67 centisomes)||Length: 1395 bp / 464 aa|
Molecular Weight of Polypeptide: 51.395 kD (from nucleotide sequence), 50 kD (experimental) [Sain80 ]
Unification Links: ASAP:ABE-0014258 , CGSC:619 , DIP:DIP-9945N , EchoBASE:EB0455 , EcoGene:EG10460 , EcoliWiki:b4348 , Mint:MINT-1225773 , OU-Microarray:b4348 , PortEco:hsdS , PR:PRO_000022930 , Pride:P05719 , Protein Model Portal:P05719 , RefSeq:NP_418768 , RegulonDB:EG10460 , SMR:P05719 , String:511145.b4348 , UniProt:P05719
|Biological Process:||GO:0006304 - DNA modification
GO:0009307 - DNA restriction-modification system [UniProtGOA11a]
|Molecular Function:||GO:0003677 - DNA binding [UniProtGOA11a, GOA01]|
|Cellular Component:||GO:0005829 - cytosol [DiazMejia09]|
|MultiFun Terms:||information transfer → DNA related → DNA restriction/modification|
|regulation → type of regulation → DNA structure level → methylation|
|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: EcoKI restriction-modification system
Subunit composition of
EcoKI restriction-modification system = [HsdM]2[HsdR]2[HsdS]
host modification; DNA methylase M = HsdM (summary available)
host restriction; endonuclease R = HsdR (summary available)
specificity determinant for hsdM and hsdR = HsdS (summary available)
EcoKI is the type IA restriction-modification enzyme complex responsible for identifying and restricting unmethylated, foreign DNA and for modifying native, hemimethylated DNA by methylation for self-identification. The three proteins which make up EcoKI-HsdR, HsdM, and HsdS-are all required for restriction. There is a complex that can form-HsdM2HsdS1-with only methyltransferase activity. HsdM and HsdS are required for methylation. HsdM contains a methyltransferase active site and a site for cofactor binding. The cofactor S-adenosylmethionine (AdoMet) acts as the methyl donor for modification. Hemimethylated DNA is preferred over unmethylated DNA as substrate for modification. Interaction of HsdS with DNA requires HsdM. HsdS contains two target recognition domains which recognize the sequence 5'AAC(N6)GTGC. One recognizes the AAC sequence, while the other recognizes the GTGC sequence. HsdR couples DNA translocation to ATP hydrolysis and contains the catalytic site for restriction of the DNA. When the EcoKI binds its target sequence, it makes another contact with the DNA which begins translocation of the DNA while still remaining bound to the target sequence, creating loops. Restriction occurs when translocation becomes stalled because enzymes run into each other, when DNA becomes too supercoiled, when the loop of DNA between two dimerized enzymes becomes taut, and when the enzyme becomes blocked, such as at Holliday junctions. Endonucleolytic activity requires Mg2+, ATP, and AdoMet [Murray00, Loenen03].
Enzymatic reaction of: type I site-specific deoxyribonuclease (EcoKI restriction-modification system)
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 b4348 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG10460; 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
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
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
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