Conserved Protein Domain Family
PTS_IIB_ascorbate

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cd05563: PTS_IIB_ascorbate 
PTS_IIB_ascorbate: subunit IIB of enzyme II (EII) of the L-ascorbate-specific phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS). In this system, EII is an L-ascorbate-specific permease with two cytoplasmic subunits (IIA and IIB) and a transmembrane channel IIC subunit. Subunits IIA, IIB, and IIC are encoded by the sgaA, sgaB, and sgaT genes of the E. coli sgaTBA operon. In some bacteria, the IIB (SgaB) domain is fused C-terminal to the IIA (SgaT) domain. The IIB domain fold includes a central four-stranded parallel open twisted beta-sheet flanked by alpha-helices on both sides. The seven major PTS systems with this IIB fold include ascorbate, chitobiose/lichenan, lactose, galactitol, mannitol, fructose, and a sensory system with similarity to the bacterial bgl system.
Statistics
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PSSM-Id: 99905
View PSSM: cd05563
Aligned: 54 rows
Threshold Bit Score: 63.6993
Threshold Setting Gi: 72080884
Created: 11-May-2007
Updated: 17-Jan-2013
Structure
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Aligned Rows:
 
Feature 1:active site [active site]
Evidence:
  • Comment:most of the active site residues are contained within a P-loop which forms part of a binding pocket for the phosphoryl group
  • Comment:for the E coli chitobiose transporter IIB subunit,(not included in this IIB subgroup) in addition to the P-loop residues, two conserved residues are likely to be important in catalysis: a tyrosine whose side-chain points towards the phosphorylation site and a Gln residue whose side-chain lies close to the sulfur atom of the catalytic cysteine.

Sequence Alignment
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Format: Row Display: Color Bits: Type Selection:
                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
Feature 1             # ##  ##                                                                   
gi 76363872    4 RILAVCGNGQGSSMIMKMKVDQFLTQSNId---HTVNSCAVGEyks--elSGADIIIASTHIag--eiTVTGNKYVVGVR 76
gi 53728914  386 RILAVCGSGQGSSMMMKMKIKQYLDKRGVp---NIMDSCAVTDhkg--kvGSVDIIVCSKHLqn--eiVANEHISVLGVQ 458
gi 145965805 510 RVLVCCGSGQGSSMMCSKKIKEFLDKKGIpattFNSAITDYKSh-----lGSFDIIVTSVALaek-itNLPEGKQQLAVK 583
gi 29375704    2 RILVSCANGSGTSLMMMRSVEKAMKELGVp--iTKIHHCAISEgks--saSQYDVVFTPVNFlqmfqqAEKRGVTVIGIK 77
gi 116496158   2 KILVSCANGSGTSLMMMRSVQKAFKRLNIp--iTQIEHTNLAEgks--taKQYDMVFTTTNFvdmfkdAQSKGVQVIGVK 77
gi 71894692    2 KILCICGSGMGTSMIIKMKANQALKELNLe---GSVESIGLGQgkt--vaINFDVIFCTQNFvd---eIPKGKTLVYGIN 73
gi 24378777    3 KVLTACGNGMGSSMVIKMKVENALRQLGV----SDIESASCSVgeakglaSNYDIVVASNHLih--elDGRTNGKLIGLD 76
gi 54020484    4 KIVAACGNGMGTSMIIKLKVQKIVKELGId---ATVEALSMGQskg--ltNSVDIIIASKHLvs--efSQKQKAKIVGVT 76
gi 148377900   2 KVLCLCGSGMGTSMIIKLKTEQAMRELGIq---GSVEALGLGMgks--vaNNFDVILCTNNFvs---eVANSKASVHGLK 73
gi 157149902   3 KIVTVCGAGVGSSMMERLFAQQILDAENIe---AEIDASDIGSvd----pNSYDIVITTSDFan---qLAHAQSKVIRID 72
                         90
                 ....*....|....*.
Feature 1                        
gi 76363872   77 NMLSPADFGPKLLEVI 92
gi 53728914  459 NMLNPNTFGEELLALI 474
gi 145965805 584 NMIMVKTFGDELISLI 599
gi 29375704   78 NVMSAKEIQEKYMASD 93
gi 116496158  78 NVMSDKEVEQHVREDT 93
gi 71894692   74 NVMDLNEIKSKILEAK 89
gi 24378777   77 NLMDDNEIKTKLEEAL 92
gi 54020484   77 NLMDENEIKTALTPVL 92
gi 148377900  74 NVMDINEIKAAFKDAL 89
gi 157149902  73 NLMDKEYLKEQLLATI 88

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