Escherichia coli K-12 substr. MG1655 Polypeptide: periplasmic binding protein SapA of predicted ABC transporter

Gene: sapA Accession Numbers: G2002 (EcoCyc), b1294, ECK1289

Regulation Summary Diagram

Regulation summary diagram for sapA

Component of: putative ABC transporter SapABCDF (extended summary available)

Locations: inner membrane, periplasmic space

Map Position: [1,353,491 <- 1,355,134] (29.17 centisomes, 105°)
Length: 1644 bp / 547 aa

Molecular Weight of Polypeptide: 61.565 kD (from nucleotide sequence)

Unification Links: ASAP:ABE-0004354, DIP:DIP-10822N, EchoBASE:EB4155, EcoGene:EG20254, EcoliWiki:b1294, Mint:MINT-1292044, ModBase:Q47622, OU-Microarray:b1294, PortEco:sapA, PR:PRO_000023904, Pride:Q47622, Protein Model Portal:Q47622, RefSeq:NP_415810, RegulonDB:G2002, SMR:Q47622, String:511145.b1294, UniProt:Q47622

Relationship Links: InterPro:IN-FAMILY:IPR000914, InterPro:IN-FAMILY:IPR023765, InterPro:IN-FAMILY:IPR030678, Pfam:IN-FAMILY:PF00496, Prosite:IN-FAMILY:PS01040

In Paralogous Gene Group: 25 (11 members)

Gene-Reaction Schematic

Gene-Reaction Schematic

GO Terms:
Biological Process:
Inferred by computational analysisGO:0006810 - transport [UniProtGOA11a]
Inferred by computational analysisGO:0015031 - protein transport [UniProtGOA11a]
Inferred by computational analysisGO:0015833 - peptide transport [UniProtGOA11a, Gaudet10]
Inferred by computational analysisGO:0055085 - transmembrane transport [GOA01a]
Molecular Function:
Inferred by computational analysisGO:0015197 - peptide transporter activity [Gaudet10]
Cellular Component:
Inferred by computational analysisGO:0030288 - outer membrane-bounded periplasmic space [Gaudet10, DiazMejia09, Linton98]
Inferred by computational analysisGO:0042597 - periplasmic space [UniProtGOA11, UniProtGOA11a]
Inferred by computational analysisGO:0043190 - ATP-binding cassette (ABC) transporter complex [GOA01a]
Inferred by computational analysisGO:0055052 - ATP-binding cassette (ABC) transporter complex, substrate-binding subunit-containing [Linton98]

MultiFun Terms: metabolismcarbon utilizationamino acids
transportChannel-type TransportersPyrophosphate Bond (ATP; GTP; P2) Hydrolysis-driven Active TransportersThe ATP-binding Cassette (ABC) Superfamily + ABC-type Uptake PermeasesABC superfamily, periplasmic binding component

Essentiality data for sapA knockouts:

Growth Medium Growth? T (°C) O2 pH Osm/L Growth Observations
LB enrichedYes 37 Aerobic 6.95   Yes [Gerdes03, Comment 1]
LB LennoxYes 37 Aerobic 7   Yes [Baba06, Comment 2]
M9 medium with 1% glycerolYes 37 Aerobic 7.2 0.35 Yes [Joyce06, Comment 3]
MOPS medium with 0.4% glucoseYes 37 Aerobic 7.2 0.22 Yes [Baba06, Comment 2]

Subunit of: putative ABC transporter SapABCDF

Inferred by computational analysis

Subunit composition of putative ABC transporter SapABCDF = [SapF][SapD][SapB][SapC][SapA]
         ATP binding protein SapF of predicted ABC transporter = SapF
         ATP binding protein implicated in Trk mediated K+ uptake = SapD (summary available)
         integral membrane protein SapB of predicted ABC transporter = SapB
         integral membrane protein SapC of predicted ABC transporter = SapC
         periplasmic binding protein SapA of predicted ABC transporter = SapA

In Salmonella typhimurium the multicistronic operon sapABCDF is required for virulence and resistance to the antimicrobial peptides melittin and protamine. Based on sequence similarity and hydrophobicity analysis, SapA is a putative periplasmic binding protein, SapB and SapC are both transmembrane proteins and SapD and SapF are the ATP-binding proteins of the complex. Thus in S. typhimurium the Sap system may mediate resistance to antimicrobial peptides by transporting them into the cytoplasm where they can be further degraded [ParraLopez93].

The Sap proteins of E. coli K-12 are highly identical to those from S. typhimurium (95-98% at the amino acid level), however their function is not fully understood and their role in resistance to antimicrobial peptides has been questioned [Stumpe, Harms01]. SapD (also known as TrkE) has been implicated in conferring ATP dependence to the K+ uptake proteins TrkG and TrkH which are not related to the ABC superfamily [Dosch91, Harms01]. Mutation experiments suggest that ATP binding to SapD rather than ATP hydrolysis is sufficient for restoring TrkH mediated K+ uptake in E. coli [Harms01].

sap: sensitive to antimicrobial peptides

Locations: inner membrane

GO Terms:
Cellular Component:
Inferred by computational analysisGO:0055052 - ATP-binding cassette (ABC) transporter complex, substrate-binding subunit-containing [Linton98]

Last-Curated 11-Feb-2014 by Mackie A, Macquarie University

Sequence Features

Protein sequence of periplasmic binding protein SapA of predicted ABC transporter with features indicated

Feature Class Location Citations Comment
Signal-Sequence 1 -> 21
Inferred by computational analysis[UniProt15]
Chain 22 -> 547
Author statement[UniProt15]
UniProt: Peptide transport periplasmic protein SapA.
Sequence-Conflict 34 -> 35
Inferred by curator[Aiba96, UniProt15]
UniProt: (in Ref. 2).
Pfam PF00496 79 -> 457
Inferred by computational analysis[Finn14]
SBP_bac_5 : Bacterial extracellular solute-binding proteins, family 5 Middle

Gene Local Context (not to scale -- see Genome Browser for correct scale)

Gene local context diagram

Transcription Unit

Transcription-unit diagram


10/20/97 Gene b1294 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene G2002.


Aiba96: Aiba H, Baba T, Hayashi K, Inada T, Isono K, Itoh T, Kasai H, Kashimoto K, Kimura S, Kitakawa M, Kitagawa M, Makino K, Miki T, Mizobuchi K, Mori H, Mori T, Motomura K, Nakade S, Nakamura Y, Nashimoto H, Nishio Y, Oshima T, Saito N, Sampei G, Horiuchi T (1996). "A 570-kb DNA sequence of the Escherichia coli K-12 genome corresponding to the 28.0-40.1 min region on the linkage map." DNA Res 3(6);363-77. PMID: 9097039

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

Dosch91: Dosch DC, Helmer GL, Sutton SH, Salvacion FF, Epstein W (1991). "Genetic analysis of potassium transport loci in Escherichia coli: evidence for three constitutive systems mediating uptake potassium." J Bacteriol 1991;173(2);687-96. PMID: 1987159

Finn14: Finn RD, Bateman A, Clements J, Coggill P, Eberhardt RY, Eddy SR, Heger A, Hetherington K, Holm L, Mistry J, Sonnhammer EL, Tate J, Punta M (2014). "Pfam: the protein families database." Nucleic Acids Res 42(Database issue);D222-30. PMID: 24288371

Gaudet10: Gaudet P, Livstone M, Thomas P (2010). "Annotation inferences using phylogenetic trees." PMID: 19578431

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

GOA01a: GOA, DDB, FB, MGI, ZFIN (2001). "Gene Ontology annotation through association of InterPro records with GO terms."

Harms01: Harms C, Domoto Y, Celik C, Rahe E, Stumpe S, Schmid R, Nakamura T, Bakker EP (2001). "Identification of the ABC protein SapD as the subunit that confers ATP dependence to the K+-uptake systems Trk(H) and Trk(G) from Escherichia coli K-12." Microbiology 2001;147(Pt 11);2991-3003. PMID: 11700350

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

Linton98: Linton KJ, Higgins CF (1998). "The Escherichia coli ATP-binding cassette (ABC) proteins." Mol Microbiol 1998;28(1);5-13. PMID: 9593292

ParraLopez93: Parra-Lopez C, Baer MT, Groisman EA (1993). "Molecular genetic analysis of a locus required for resistance to antimicrobial peptides in Salmonella typhimurium." EMBO J 1993;12(11);4053-62. PMID: 8223423

Stumpe: Stumpe S, Bakker EP "Requirement of a large K+-uptake capacity and of extracytoplasmic protease activity for protamine resistance of Escherichia coli." Arch Microbiol 167(2-3);126-36. PMID: 9133319

UniProt15: UniProt Consortium (2015). "UniProt version 2015-08 released on 2015-07-22." 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."

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