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3.A.1.1.10
Alginate (MW 27,000 Da) (and Alginate oligosaccharides) uptake porter. Sphingomonas species A1 is a 'pit-forming' bacterium that directly incorporates alginate into its cytoplasm through a pit-dependent transport system, termed a 'superchannel' (Murata et al., 2008). The pit is a novel organ acquired through the fluidity and reconstitution of cell surface molecules, and through cooperation with the transport machinery in the cells. It confers upon bacterial cells a more efficient way to secure and assimilate macromolecules (Murata et al., 2008).  The substrate-transport characteristics and quaternary structure of AlgM1M2SS with AlgQ1 have been determined (Maruyama et al. 2015). The addition of poly- or oligoalginate enhanced the ATPase activity of reconstituted AlgM1M2SS coupled with one of the periplasmic solute-binding proteins, AlgQ1 or AlgQ2. External fluorescence-labeled oligoalginates were specifically imported into AlgM1M2SS-containing proteoliposomes in the presence of AlgQ2, ATP, and Mg2+. The crystal structure of AlgQ2-bound AlgM1M2SS adopts an inward-facing conformation. The interaction between AlgQ2 and AlgM1M2SS induces the formation of an alginate-binding tunnel-like structure accessible to solvent. The translocation route inside the transmembrane domains contains charged residues suitable for the import of acidic saccharides (Maruyama et al. 2015).

Accession Number:Q9KWT5
Protein Name:AlgQ2
Length:516
Molecular Weight:59611.00
Species:Sphingomonas sp [28214]
Number of TMSs:1
Location1 / Topology2 / Orientation3: Membrane1 / Multi-pass membrane protein2
Substrate Alginate

Cross database links:

Pfam: PF01547   

Gene Ontology

GO:0005215 F:transporter activity
GO:0006810 P:transport

References (3)

[1] “A novel bacterial ATP-binding cassette transporter system that allows uptake of macromolecules.”  Momma K.et.al.   10869078
[2] “Crystal structure of AlgQ2, a macromolecule (alginate)-binding protein of Sphingomonas sp. A1 at 2.0A resolution.”  Momma K.et.al.   11884143
[3] “Crystal structure of AlgQ2, a macromolecule (alginate)-binding protein of Sphingomonas sp. A1, complexed with an alginate tetrasaccharide at 1.6-A resolution.”  Mishima Y.et.al.   12486124
Structure:
1J1N   1KWH   4TQU   4XIG   4XTC   5H6U   5H71   6JHX     

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Predict TMSs (Predict number of transmembrane segments)
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FASTA formatted sequence
1:	MKKMMLSVAA VATLMAFAAP VATAKEATWV TDKPLTLKIH MHFRDKWVWD ENWPVAKESF 
61:	RLTNVKLQSV ANKAATNSQE QFNLMMASGD LPDVVGGDNL KDKFIQYGQE GAFVPLNKLI 
121:	DQYAPHIKAF FKSHPEVERA IKAPDGNIYF IPYVPDGVVA RGYFIREDWL KKLNLKPPQN 
181:	IDELYTVLKA FKEKDPNGNG KADEVPFIDR HPDEVFRLVN FWGARSSGSD NYMDFYIDNG 
241:	RVKHPWAETA FRDGMKHVAQ WYKEGLIDKE IFTRKARARE QMFGGNLGGF THDWFASTMT 
301:	FNEGLAKTVP GFKLIPIAPP TNSKGQRWEE DSRQKVRPDG WAITVKNKNP VETIKFFDFY 
361:	FSRPGRDISN FGVPGVTYDI KNGKAVFKDS VLKSPQPVNN QLYDMGAQIP IGFWQDYDYE 
421:	RQWTTPEAQA GIDMYVKGKY VMPGFEGVNM TREERAIYDK YWADVRTYMY EMGQAWVMGT 
481:	KDVDKTWDEY QRQLKLRGLY QVLQMMQQAY DRQYKN