Conserved Protein Domain Family
LbH_SAT

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cd03354: LbH_SAT 
Click on image for an interactive view with Cn3D
Serine acetyltransferase (SAT): SAT catalyzes the CoA-dependent acetylation of the side chain hydroxyl group of L-serine to form O-acetylserine, as the first step of a two-step biosynthetic pathway in bacteria and plants leading to the formation of L-cysteine. This reaction represents a key metabolic point of regulation for the cysteine biosynthetic pathway due to its feedback inhibition by cysteine. The enzyme is a 175 kDa homohexamer, composed of a dimer of homotrimers. Each subunit contains an N-terminal alpha helical region and a C-terminal left-handed beta-helix (LbH) subdomain with 5 turns, each containing a hexapeptide repeat motif characteristic of the acyltransferase superfamily of enzymes. The trimer interface mainly involves the C-terminal LbH subdomain while the dimer (of trimers) interface is mediated by the N-terminal alpha helical subdomain.
Statistics
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PSSM-Id: 100045
View PSSM: cd03354
Aligned: 115 rows
Threshold Bit Score: 104.059
Threshold Setting Gi: 15824375
Created: 16-Aug-2001
Updated: 17-Jan-2013
Structure
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Program:
Drawing:
Aligned Rows:
 
Conserved site includes 16 residues -Click on image for an interactive view with Cn3D
Feature 1:active site [active site]
Evidence:
  • Comment:Based on the structures of serine acetyltransferase bound to CoA (1SST) and substrate (1T3D).
  • Comment:Serine acetyltransferase is hexameric, composed of a dimer of homotrimers. The active sites are located at the interface between two LbH subunits in the homotrimer. The trimer structure contains three active sites and each subunit contributes to two active sites via residues located on two surfaces.

Sequence Alignment
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Format: Row Display: Color Bits: Type Selection:
                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
Feature 1                         ##                        ##     ##        ##          #       
1T3D_C       156 FQVDIHPaAKIGRGIXLDHa-----TGIVVGEtAVIENd-VSILQsVTLGGTgks--ggdRHPKIREGVXIGAGAKILGn 227
1SST_A       136 FDVDIHPaAKIGHGIMFDHa-----TGIVVGEtSVIENd-VSILQgVTLGGTgke--sgdRHPKVREGVMIGAGAKILGn 207
gi 39983948   73 YGISIPYnTDIGPGLYIGHf-----GGIIVNAeATIGRn-CNINQeVTVGATygg--kypGTPVIMNNVYLGPGSKIIGg 144
gi 52216942   72 TGVQISPyADIDGGLAIAHf-----SCIVISD-CKIGKh-FTIMQgSTIGSYrgs--ikgGSPSIGDNVVICAGAKVIGn 142
gi 156860676  73 TGIQIGFgTKIGKALMFPHy-----SCIVINGsAIIGDn-CTIYHgVTVGSVrgp---kgGAPHIGNNVVIASGAKVIGn 143
gi 156860682  78 FGIQMPLgTPVKGGLSFNHf-----SCIIINGaTQIGHn-CTIFHgVTTALKmgg--snaGVPSIGNNCVLGPGSKILGs 149
gi 60493708   75 LKITIYP-NTIGAGLRIYHv----gDFIHIGAqCHIGHn-CTLLPgVVFGNKyek--atdTQIIAGNNCYFGLGAKIFGs 146
gi 71147417   54 AYFFQWL-NKLVNGCVIGSganfssGFVIMHPiGIVINskVIGGHnITLESGvvigdekgKSPCLENNIFIGSGAKIIGq 132
gi 71281677   65 NGCVIGSgANFSSGFVIMHp-----IGIVINSkVIGGHn-ITLESgVVIGDEk------gKSPCLENNIFIGSGAKIIGq 132
gi 56421844   59 IGSDIPKqIECGEGLRIPHg----gRGIIIHPtVKIGKn-VTIFHqVTIGVKep----iiQGATIENNVYIGAGAKIIGs 129
                         90       100
                 ....*....|....*....|....*....
Feature 1               # ##  # #       #    #
1T3D_C       228 IEVGRGAKIGAGSVVLQPVPPHTTAAGVP 256
1SST_A       208 IEVGKYAKIGANSVVLNPVPEYATAAGVP 236
gi 39983948  145 ITLGSHAAVGANCVVTKPVPDHGVVVGIP 173
gi 52216942  143 IKLGNNAMVGANAVVVKDIPDNAVVAGVP 171
gi 156860676 144 ITIGNNVMIGSGAIVVTDIPDNSVVVGNP 172
gi 156860682 150 VTLGDNVFVGANAVVTHDMPSNSIVAGIP 178
gi 60493708  147 IIIGNNVTIGANAVVTKDIPDNAIVGGIP 175
gi 71147417  133 LSIEDNVKIGANAVLTKDAKYGSTMLGIP 161
gi 71281677  133 LSIEDNVKIGANAVLTKDAKYGSTMLGIP 161
gi 56421844  130 VLIGENCRIGANAVVVKDVPPNSTVVGIP 158

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