Skip Header

You are using a version of browser that may not display all the features of this website. Please consider upgrading your browser.
Protein

Dimethyl sulfoxide reductase DmsA

Gene

dmsA

Organism
Escherichia coli (strain K12)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

Catalyzes the reduction of dimethyl sulfoxide (DMSO) to dimethyl sulfide (DMS). DMSO reductase serves as the terminal reductase under anaerobic conditions, with DMSO being the terminal electron acceptor. Terminal reductase during anaerobic growth on various sulfoxides and N-oxide compounds. Allows E.coli to grow anaerobically on DMSO as respiratory oxidant.1 Publication

Catalytic activityi

Dimethylsulfide + menaquinone + H2O = dimethylsulfoxide + menaquinol.

Cofactori

Protein has several cofactor binding sites:

Enzyme regulationi

Inhibited by dithionite, sodium bisulfite and tungstate.2 Publications

Kineticsi

  1. KM=0.043 mM for 2-chloropyridine N-oxide (at pH 5 and at 30 degrees Celsius, PubMed:8969520)2 Publications
  2. KM=0.045 mM for 3-amidopyridine N-oxide (at pH 5 and at 30 degrees Celsius, PubMed:8969520)2 Publications
  3. KM=0.06 mM for tertramethylene sulfoxide (at pH 5 and at 30 degrees Celsius, PubMed:8969520)2 Publications
  4. KM=0.09 mM for methionine sulfoxide (at pH 5 and at 30 degrees Celsius, PubMed:8969520)2 Publications
  5. KM=0.246 mM for 4-phenylpyridine N-oxide (at pH 5 and at 30 degrees Celsius, PubMed:8969520)2 Publications
  6. KM=0.830 mM for dimethyldodecylamin N-oxide (at pH 5 and at 30 degrees Celsius, PubMed:8969520)2 Publications
  7. KM=0.18 mM for DMSO (at pH 6.8 and at 23 degrees Celsius, PubMed:3280546)2 Publications
  8. KM=0.47 mM for L-methionine sulfoxide (at pH 6.8 and at 23 degrees Celsius, PubMed:3280546)2 Publications
  9. KM=0.5 mM for nicotinamide N-oxide (at pH 6.8 and at 23 degrees Celsius, PubMed:3280546)2 Publications
  10. KM=0.6 mM for TMAO (at pH 6.8 and at 23 degrees Celsius, PubMed:3280546)2 Publications
  11. KM=1.0 mM for 4-picoline N-oxide (at pH 6.8 and at 23 degrees Celsius, PubMed:3280546)2 Publications
  12. KM=20.2 mM for TMAO (at pH 5 and at 30 degrees Celsius, PubMed:8969520)2 Publications

    Sites

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Metal bindingi63 – 631Iron-sulfur (4Fe-4S)PROSITE-ProRule annotation
    Metal bindingi67 – 671Iron-sulfur (4Fe-4S)PROSITE-ProRule annotation
    Metal bindingi71 – 711Iron-sulfur (4Fe-4S)PROSITE-ProRule annotation
    Metal bindingi104 – 1041Iron-sulfur (4Fe-4S)PROSITE-ProRule annotation
    Metal bindingi205 – 2051MolybdenumBy similarity
    Binding sitei390 – 3901Molybdopterin guanine dinucleotide 1By similarity
    Binding sitei488 – 4881Molybdopterin guanine dinucleotide 1By similarity
    Binding sitei788 – 7881Molybdopterin guanine dinucleotide 1By similarity

    GO - Molecular functioni

    • 4 iron, 4 sulfur cluster binding Source: EcoCyc
    • cofactor binding Source: EcoCyc
    • dimethyl sulfoxide reductase activity Source: InterPro
    • electron carrier activity Source: EcoCyc
    • molybdenum ion binding Source: InterPro
    • NADH dehydrogenase activity Source: GO_Central

    GO - Biological processi

    • anaerobic respiration Source: EcoCyc
    Complete GO annotation...

    Keywords - Molecular functioni

    Oxidoreductase

    Keywords - Ligandi

    4Fe-4S, Iron, Iron-sulfur, Metal-binding, Molybdenum

    Enzyme and pathway databases

    BioCyciEcoCyc:DMSA-MONOMER.
    ECOL316407:JW5118-MONOMER.
    MetaCyc:DMSA-MONOMER.
    BRENDAi1.8.5.3. 2026.

    Protein family/group databases

    TCDBi5.A.3.3.2. the prokaryotic molybdopterin-containing oxidoreductase (pmo) family.

    Names & Taxonomyi

    Protein namesi
    Recommended name:
    Dimethyl sulfoxide reductase DmsA (EC:1.8.5.3)
    Short name:
    DMSO reductase
    Short name:
    DMSOR
    Short name:
    Me2SO reductase
    Gene namesi
    Name:dmsA
    Ordered Locus Names:b0894, JW5118
    OrganismiEscherichia coli (strain K12)
    Taxonomic identifieri83333 [NCBI]
    Taxonomic lineageiBacteriaProteobacteriaGammaproteobacteriaEnterobacterialesEnterobacteriaceaeEscherichia
    Proteomesi
    • UP000000318 Componenti: Chromosome
    • UP000000625 Componenti: Chromosome

    Organism-specific databases

    EcoGeneiEG10232. dmsA.

    Subcellular locationi

    • Cell membrane 2 Publications; Peripheral membrane protein 2 Publications; Cytoplasmic side 2 Publications

    GO - Cellular componenti

    • dimethyl sulfoxide reductase complex Source: EcoCyc
    • intrinsic component of periplasmic side of plasma membrane Source: EcoCyc
    Complete GO annotation...

    Keywords - Cellular componenti

    Cell membrane, Membrane

    Pathology & Biotechi

    Mutagenesis

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Mutagenesisi17 – 171R → S: Not targeted to the membrane, does not support anaerobic growth. 1 Publication
    Mutagenesisi57 – 571K → D: No alteration of the growth, expression, or catalytic activities. 1 Publication
    Mutagenesisi67 – 671C → S: Electron transfer from the 4Fe-4S clusters of DmsB to the Mo-bisMGD of DmsA is blocked. Little effect on the coordination sphere of the molybdenum and only minor effects on its redox chemistry. 2 Publications
    Mutagenesisi71 – 711C → S: Can not support growth. 1 Publication
    Mutagenesisi104 – 1041C → S: No alteration of the growth, expression, or catalytic activities. 1 Publication
    Mutagenesisi106 – 1061R → S: Electron transfer from the 4Fe-4S clusters of DmsB to the Mo-bisMGD of DmsA is blocked. Little effect on the coordination sphere of the molybdenum and only minor effects on its redox chemistry. 2 Publications

    PTM / Processingi

    Molecule processing

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Signal peptidei1 – 4545Tat-type signalPROSITE-ProRule annotation1 PublicationAdd
    BLAST
    Chaini46 – 814769Dimethyl sulfoxide reductase DmsAPRO_0000019143Add
    BLAST

    Post-translational modificationi

    Exported by the Tat system. The position of the signal peptide cleavage has been experimentally proven. Can also be exported by the Sec system.

    Proteomic databases

    PaxDbiP18775.
    PRIDEiP18775.

    Interactioni

    Subunit structurei

    Heterotrimeric enzyme composed of a catalytic heterodimer (DmsAB) and a membrane anchor protein (DmsC).1 Publication

    Binary interactionsi

    WithEntry#Exp.IntActNotes
    dmsDP698537EBI-4411104,EBI-4406374

    Protein-protein interaction databases

    BioGridi4261945. 15 interactions.
    DIPiDIP-9452N.
    IntActiP18775. 8 interactions.
    MINTiMINT-8046334.
    STRINGi511145.b0894.

    Structurei

    3D structure databases

    ProteinModelPortaliP18775.
    SMRiP18775. Positions 56-431.
    ModBaseiSearch...
    MobiDBiSearch...

    Family & Domainsi

    Domains and Repeats

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Domaini56 – 118634Fe-4S Mo/W bis-MGD-typePROSITE-ProRule annotationAdd
    BLAST

    Region

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Regioni172 – 1765MGD 1 bindingBy similarity
    Regioni244 – 2452MGD 2 bindingBy similarity
    Regioni270 – 2712MGD 2 bindingBy similarity
    Regioni291 – 2933MGD 2 bindingBy similarity
    Regioni386 – 3872MGD 2 bindingBy similarity
    Regioni512 – 5132MGD 1 bindingBy similarity
    Regioni701 – 7011MGD 1 bindingBy similarity
    Regioni707 – 7093MGD 1 bindingBy similarity
    Regioni804 – 8052MGD 1 bindingBy similarity

    Sequence similaritiesi

    Contains 1 4Fe-4S Mo/W bis-MGD-type domain.PROSITE-ProRule annotation

    Keywords - Domaini

    Signal

    Phylogenomic databases

    eggNOGiENOG4107QY8. Bacteria.
    COG0243. LUCA.
    HOGENOMiHOG000284390.
    InParanoidiP18775.
    KOiK07306.
    OMAiFRQQGIF.
    OrthoDBiEOG6GFGF8.
    PhylomeDBiP18775.

    Family and domain databases

    InterProiIPR011888. Anaer_DMSO_reductase.
    IPR009010. Asp_de-COase-like_dom.
    IPR006657. MoPterin_dinucl-bd_dom.
    IPR006656. Mopterin_OxRdtase.
    IPR006963. Mopterin_OxRdtase_4Fe-4S_dom.
    IPR006655. Mopterin_OxRdtase_prok_CS.
    IPR027467. MopterinOxRdtase_cofactor_BS.
    IPR006311. TAT_signal.
    IPR019546. TAT_signal_bac_arc.
    [Graphical view]
    PfamiPF04879. Molybdop_Fe4S4. 1 hit.
    PF00384. Molybdopterin. 1 hit.
    PF01568. Molydop_binding. 1 hit.
    [Graphical view]
    SMARTiSM00926. Molybdop_Fe4S4. 1 hit.
    [Graphical view]
    SUPFAMiSSF50692. SSF50692. 1 hit.
    TIGRFAMsiTIGR02166. dmsA_ynfE. 1 hit.
    TIGR01409. TAT_signal_seq. 1 hit.
    PROSITEiPS51669. 4FE4S_MOW_BIS_MGD. 1 hit.
    PS00551. MOLYBDOPTERIN_PROK_1. 1 hit.
    PS00490. MOLYBDOPTERIN_PROK_2. 1 hit.
    PS00932. MOLYBDOPTERIN_PROK_3. 1 hit.
    PS51318. TAT. 1 hit.
    [Graphical view]

    Sequencei

    Sequence statusi: Complete.

    Sequence processingi: The displayed sequence is further processed into a mature form.

    P18775-1 [UniParc]FASTAAdd to basket

    « Hide

            10         20         30         40         50
    MKTKIPDAVL AAEVSRRGLV KTTAIGGLAM ASSALTLPFS RIAHAVDSAI
    60 70 80 90 100
    PTKSDEKVIW SACTVNCGSR CPLRMHVVDG EIKYVETDNT GDDNYDGLHQ
    110 120 130 140 150
    VRACLRGRSM RRRVYNPDRL KYPMKRVGAR GEGKFERISW EEAYDIIATN
    160 170 180 190 200
    MQRLIKEYGN ESIYLNYGTG TLGGTMTRSW PPGNTLVARL MNCCGGYLNH
    210 220 230 240 250
    YGDYSSAQIA EGLNYTYGGW ADGNSPSDIE NSKLVVLFGN NPGETRMSGG
    260 270 280 290 300
    GVTYYLEQAR QKSNARMIII DPRYTDTGAG REDEWIPIRP GTDAALVNGL
    310 320 330 340 350
    AYVMITENLV DQAFLDKYCV GYDEKTLPAS APKNGHYKAY ILGEGPDGVA
    360 370 380 390 400
    KTPEWASQIT GVPADKIIKL AREIGSTKPA FISQGWGPQR HANGEIATRA
    410 420 430 440 450
    ISMLAILTGN VGINGGNSGA REGSYSLPFV RMPTLENPIQ TSISMFMWTD
    460 470 480 490 500
    AIERGPEMTA LRDGVRGKDK LDVPIKMIWN YAGNCLINQH SEINRTHEIL
    510 520 530 540 550
    QDDKKCELIV VIDCHMTSSA KYADILLPDC TASEQMDFAL DASCGNMSYV
    560 570 580 590 600
    IFNDQVIKPR FECKTIYEMT SELAKRLGVE QQFTEGRTQE EWMRHLYAQS
    610 620 630 640 650
    REAIPELPTF EEFRKQGIFK KRDPQGHHVA YKAFREDPQA NPLTTPSGKI
    660 670 680 690 700
    EIYSQALADI AATWELPEGD VIDPLPIYTP GFESYQDPLN KQYPLQLTGF
    710 720 730 740 750
    HYKSRVHSTY GNVDVLKAAC RQEMWINPLD AQKRGIHNGD KVRIFNDRGE
    760 770 780 790 800
    VHIEAKVTPR MMPGVVALGE GAWYDPDAKR VDKGGCINVL TTQRPSPLAK
    810
    GNPSHTNLVQ VEKV
    Length:814
    Mass (Da):90,399
    Last modified:December 1, 2000 - v2
    Checksum:iB97C830ABAC7C32C
    GO

    Sequence cautioni

    The sequence AAA83843.1 differs from that shown. Reason: Erroneous initiation. Translation N-terminally extended.Curated

    Sequence databases

    Select the link destinations:
    EMBLi
    GenBanki
    DDBJi
    Links Updated
    J03412 Genomic DNA. Translation: AAA83843.1. Different initiation.
    U00096 Genomic DNA. Translation: AAC73980.2.
    AP009048 Genomic DNA. Translation: BAA35626.2.
    PIRiS03785.
    RefSeqiNP_415414.4. NC_000913.3.
    WP_000850303.1. NZ_LN832404.1.

    Genome annotation databases

    EnsemblBacteriaiAAC73980; AAC73980; b0894.
    BAA35626; BAA35626; BAA35626.
    GeneIDi945508.
    KEGGiecj:JW5118.
    eco:b0894.
    PATRICi32116999. VBIEscCol129921_0924.

    Cross-referencesi

    Sequence databases

    Select the link destinations:
    EMBLi
    GenBanki
    DDBJi
    Links Updated
    J03412 Genomic DNA. Translation: AAA83843.1. Different initiation.
    U00096 Genomic DNA. Translation: AAC73980.2.
    AP009048 Genomic DNA. Translation: BAA35626.2.
    PIRiS03785.
    RefSeqiNP_415414.4. NC_000913.3.
    WP_000850303.1. NZ_LN832404.1.

    3D structure databases

    ProteinModelPortaliP18775.
    SMRiP18775. Positions 56-431.
    ModBaseiSearch...
    MobiDBiSearch...

    Protein-protein interaction databases

    BioGridi4261945. 15 interactions.
    DIPiDIP-9452N.
    IntActiP18775. 8 interactions.
    MINTiMINT-8046334.
    STRINGi511145.b0894.

    Protein family/group databases

    TCDBi5.A.3.3.2. the prokaryotic molybdopterin-containing oxidoreductase (pmo) family.

    Proteomic databases

    PaxDbiP18775.
    PRIDEiP18775.

    Protocols and materials databases

    Structural Biology KnowledgebaseSearch...

    Genome annotation databases

    EnsemblBacteriaiAAC73980; AAC73980; b0894.
    BAA35626; BAA35626; BAA35626.
    GeneIDi945508.
    KEGGiecj:JW5118.
    eco:b0894.
    PATRICi32116999. VBIEscCol129921_0924.

    Organism-specific databases

    EchoBASEiEB0228.
    EcoGeneiEG10232. dmsA.

    Phylogenomic databases

    eggNOGiENOG4107QY8. Bacteria.
    COG0243. LUCA.
    HOGENOMiHOG000284390.
    InParanoidiP18775.
    KOiK07306.
    OMAiFRQQGIF.
    OrthoDBiEOG6GFGF8.
    PhylomeDBiP18775.

    Enzyme and pathway databases

    BioCyciEcoCyc:DMSA-MONOMER.
    ECOL316407:JW5118-MONOMER.
    MetaCyc:DMSA-MONOMER.
    BRENDAi1.8.5.3. 2026.

    Miscellaneous databases

    PROiP18775.

    Family and domain databases

    InterProiIPR011888. Anaer_DMSO_reductase.
    IPR009010. Asp_de-COase-like_dom.
    IPR006657. MoPterin_dinucl-bd_dom.
    IPR006656. Mopterin_OxRdtase.
    IPR006963. Mopterin_OxRdtase_4Fe-4S_dom.
    IPR006655. Mopterin_OxRdtase_prok_CS.
    IPR027467. MopterinOxRdtase_cofactor_BS.
    IPR006311. TAT_signal.
    IPR019546. TAT_signal_bac_arc.
    [Graphical view]
    PfamiPF04879. Molybdop_Fe4S4. 1 hit.
    PF00384. Molybdopterin. 1 hit.
    PF01568. Molydop_binding. 1 hit.
    [Graphical view]
    SMARTiSM00926. Molybdop_Fe4S4. 1 hit.
    [Graphical view]
    SUPFAMiSSF50692. SSF50692. 1 hit.
    TIGRFAMsiTIGR02166. dmsA_ynfE. 1 hit.
    TIGR01409. TAT_signal_seq. 1 hit.
    PROSITEiPS51669. 4FE4S_MOW_BIS_MGD. 1 hit.
    PS00551. MOLYBDOPTERIN_PROK_1. 1 hit.
    PS00490. MOLYBDOPTERIN_PROK_2. 1 hit.
    PS00932. MOLYBDOPTERIN_PROK_3. 1 hit.
    PS51318. TAT. 1 hit.
    [Graphical view]
    ProtoNetiSearch...

    Publicationsi

    « Hide 'large scale' publications
    1. "Nucleotide sequence of the dmsABC operon encoding the anaerobic dimethylsulphoxide reductase of Escherichia coli."
      Bilous P.T., Cole S.T., Anderson W.F., Weiner J.H.
      Mol. Microbiol. 2:785-795(1988) [PubMed] [Europe PMC] [Abstract]
      Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA], PROTEIN SEQUENCE OF 46-51, FUNCTION AS A DIMETHYLSULPHOXIDE REDUCTASE.
      Strain: K12 / C600 / ATCC 23724 / DSM 3925 / LMG 3041 / NCIB 10222.
    2. Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
      Strain: K12 / W3110 / ATCC 27325 / DSM 5911.
    3. Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
      Strain: K12 / MG1655 / ATCC 47076.
    4. "Highly accurate genome sequences of Escherichia coli K-12 strains MG1655 and W3110."
      Hayashi K., Morooka N., Yamamoto Y., Fujita K., Isono K., Choi S., Ohtsubo E., Baba T., Wanner B.L., Mori H., Horiuchi T.
      Mol. Syst. Biol. 2:E1-E5(2006) [PubMed] [Europe PMC] [Abstract]
      Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
      Strain: K12 / W3110 / ATCC 27325 / DSM 5911.
    5. "Purification and properties of Escherichia coli dimethyl sulfoxide reductase, an iron-sulfur molybdoenzyme with broad substrate specificity."
      Weiner J.H., MacIsaac D.P., Bishop R.E., Bilous P.T.
      J. Bacteriol. 170:1505-1510(1988) [PubMed] [Europe PMC] [Abstract]
      Cited for: SUBSTRATE SPECIFICITY, BIOPHYSICOCHEMICAL PROPERTIES, SUBCELLULAR LOCATION, SUBUNIT, COFACTOR.
    6. "Organization of dimethyl sulfoxide reductase in the plasma membrane of Escherichia coli."
      Sambasivarao D., Scraba D.G., Trieber C., Weiner J.H.
      J. Bacteriol. 172:5938-5948(1990) [PubMed] [Europe PMC] [Abstract]
      Cited for: SUBCELLULAR LOCATION.
    7. "Multiple pathways of electron transfer in dimethyl sulfoxide reductase of Escherichia coli."
      Trieber C.A., Rothery R.A., Weiner J.H.
      J. Biol. Chem. 269:7103-7109(1994) [PubMed] [Europe PMC] [Abstract]
      Cited for: MUTAGENESIS OF LYS-57; CYS-67; CYS-71; CYS-104 AND ARG-106.
    8. "Association of molybdopterin guanine dinucleotide with Escherichia coli dimethyl sulfoxide reductase: effect of tungstate and a mob mutation."
      Rothery R.A., Grant J.L., Johnson J.L., Rajagopalan K.V., Weiner J.H.
      J. Bacteriol. 177:2057-2063(1995) [PubMed] [Europe PMC] [Abstract]
      Cited for: COFACTOR, ENZYME REGULATION.
    9. "Kinetic analysis and substrate specificity of Escherichia coli dimethyl sulfoxide reductase."
      Simala-Grant J.L., Weiner J.H.
      Microbiology 142:3231-3239(1996) [PubMed] [Europe PMC] [Abstract]
      Cited for: BIOPHYSICOCHEMICAL PROPERTIES, ENZYME REGULATION, SUBSTRATE SPECIFICITY.
    10. "Interactions between the molybdenum cofactor and iron-sulfur clusters of Escherichia coli dimethylsulfoxide reductase."
      Rothery R.A., Trieber C.A., Weiner J.H.
      J. Biol. Chem. 274:13002-13009(1999) [PubMed] [Europe PMC] [Abstract]
      Cited for: MUTAGENESIS OF CYS-67 AND ARG-106, COFACTOR.
    11. "Multiple roles for the twin arginine leader sequence of dimethyl sulfoxide reductase of Escherichia coli."
      Sambasivarao D., Turner R.J., Simala-Grant J.L., Shaw G., Hu J., Weiner J.H.
      J. Biol. Chem. 275:22526-22531(2000) [PubMed] [Europe PMC] [Abstract]
      Cited for: EXPORT VIA THE TAT-SYSTEM, MUTAGENESIS OF ARG-17.
    12. "Export pathway selectivity of Escherichia coli twin arginine translocation signal peptides."
      Tullman-Ercek D., DeLisa M.P., Kawarasaki Y., Iranpour P., Ribnicky B., Palmer T., Georgiou G.
      J. Biol. Chem. 282:8309-8316(2007) [PubMed] [Europe PMC] [Abstract]
      Cited for: EXPORT VIA THE TAT-SYSTEM AND THE SEC-SYSTEM.
    13. "Visualizing interactions along the Escherichia coli twin-arginine translocation pathway using protein fragment complementation."
      Kostecki J.S., Li H., Turner R.J., DeLisa M.P.
      PLoS ONE 5:E9225-E9225(2010) [PubMed] [Europe PMC] [Abstract]
      Cited for: INTERACTION OF SIGNAL PEPTIDE WITH DMSD; TATB AND TATC, MUTAGENESIS OF 17-ARG-ARG-18.

    Entry informationi

    Entry nameiDMSA_ECOLI
    AccessioniPrimary (citable) accession number: P18775
    Entry historyi
    Integrated into UniProtKB/Swiss-Prot: November 1, 1990
    Last sequence update: December 1, 2000
    Last modified: March 16, 2016
    This is version 152 of the entry and version 2 of the sequence. [Complete history]
    Entry statusiReviewed (UniProtKB/Swiss-Prot)
    Annotation programProkaryotic Protein Annotation Program

    Miscellaneousi

    Miscellaneous

    The Tat signal sequence is essential for the expression of dmsA, the stability of the DmsAB dimer and membrane targeting. Despite the presence of a signal sequence, DmsA is not exported to the periplasm.

    Keywords - Technical termi

    Complete proteome, Direct protein sequencing, Reference proteome

    Documents

    1. Escherichia coli
      Escherichia coli (strain K12): entries and cross-references to EcoGene
    2. SIMILARITY comments
      Index of protein domains and families

    Similar proteinsi

    Links to similar proteins from the UniProt Reference Clusters (UniRef) at 100%, 90% and 50% sequence identity:
    100%UniRef100 combines identical sequences and sub-fragments with 11 or more residues from any organism into one UniRef entry.
    90%UniRef90 is built by clustering UniRef100 sequences that have at least 90% sequence identity to, and 80% overlap with, the longest sequence (a.k.a seed sequence).
    50%UniRef50 is built by clustering UniRef90 seed sequences that have at least 50% sequence identity to, and 80% overlap with, the longest sequence in the cluster.