Conserved Protein Domain Family
S26_SPase_I

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cd06530: S26_SPase_I 
Click on image for an interactive view with Cn3D
The S26 Type I signal peptidase (SPase; LepB; leader peptidase B; leader peptidase I; EC 3.4.21.89) family members are essential membrane-bound serine proteases that function to cleave the amino-terminal signal peptide extension from proteins that are translocated across biological membranes. The bacterial signal peptidase I, which is the most intensively studied, has two N-terminal transmembrane segments inserted in the plasma membrane and a hydrophilic, C-terminal catalytic region that is located in the periplasmic space. Although the bacterial signal peptidase I is monomeric, signal peptidases of eukaryotic cells commonly function as oligomeric complexes containing two divergent copies of the catalytic monomer. These are the IMP1 and IMP2 signal peptidases of the mitochondrial inner membrane that remove leader peptides from nuclear- and mitochondrial-encoded proteins. Also, two components of the endoplasmic reticulum signal peptidase in mammals (18-kDa and 21-kDa) belong to this family and they process many proteins that enter the ER for retention or for export to the Golgi apparatus, secretory vesicles, plasma membranes or vacuole. An atypical member of the S26 SPase type I family is the TraF peptidase which has the remarkable activity of producing a cyclic protein of the Pseudomonas pilin system. The type I signal peptidases are unique serine proteases that utilize a serine/lysine catalytic dyad mechanism in place of the classical serine/histidine/aspartic acid catalytic triad mechanism.
Statistics
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PSSM-Id: 119398
View PSSM: cd06530
Aligned: 377 rows
Threshold Bit Score: 37.5651
Threshold Setting Gi: 166032689
Created: 25-Jul-2008
Updated: 17-Jan-2013
Structure
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Program:
Drawing:
Aligned Rows:
 
Catalytic site
Conserved site includes 2 residues -Click on image for an interactive view with Cn3D
Feature 1:Catalytic site [active site]
Evidence:
  • Comment:These serine proteases carry out catalysis using a serine/lysine dyad instead of the prototypical serine/histidine/aspartic acid triad found in most serine proteases.
  • Structure:1T7D: Lipopeptide inhibitor arylomycin A2 blocks the active site of Escherichia coli type I signal peptidase
    View structure with Cn3D
  • Structure:1B12: A beta-lactam inhibitor, (5S,6S)-penem, blocks the active site of Escherichia coli type I signal peptidase
    View structure with Cn3D
  • Citation:PMID 982390

Sequence Alignment
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Format: Row Display: Color Bits: Type Selection:
                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
Feature 1                #                                                               #       
1T7D_A         9 EPFQIPSGSMmptllIGDFILVEkfaygikdpiyqktlietghpkrGDIVVFKYped---------pklDYIKRAVGlpg 79
gi 56962527   45 TSYTILSNSMeptfsAGDVVIMKknee----------------psiGDVVTFMApe-----------rrLFTHRIVEkfe 97
gi 72163360  110 QALIVLSGSMepalpVGSVVIAGpveph--------------eidvGDIITFTHadpaqtevantttlpLVTHRVIDiet 175
gi 88854719   57 TPLTVLTSSMepglpPGTLVVVKpidpn--------------eiamGDVITYQIesg---------kpgVITHRVTGvtn 113
gi 119718456  42 TPFAVLTGSMrpvmpPGTLVVVRpvdpa--------------didvGSVITFMPreh---------dpaVVTHRVVGvgf 98
gi 148272427  74 VPLTILTQSMeptlpPGTLIVVRpvdpd--------------aleiGDVATYQIrsg---------dpaVITHRITAias 130
gi 153895520  42 ESFVVLTPSMtpeiaPGDVVIVAerdpt--------------aiveGDVITFARgas----------dvPVTHRVIDvvd 97
gi 163841710  57 ETFTVLTGSMrpglqPGDLLVIKatpve--------------nisiGSVVSYQLnsg---------lsdVVTHRVVGisv 113
gi 169174711  66 QTSTMLTGSMsplinPGDVVVSVptpvt--------------dlkvGDIVTYHIpve---------dqrIETHRVTDvtr 122
gi 170783102  65 RFVPVLSDSMapgmpVGSLAITAptpra--------------evatGDVVVFTApsg---------prvRVIHRVTHvfg 121
                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
Feature 1                                                                                        
1T7D_A        80 dkvtydpvskeltiqpgcssgqacenalpvtysnvepsdfvqtfsrrnggeatsgffevpknetkengirlserketlgd 159
gi 56962527   98 sn------------------------------------------------------------------------------ 99
gi 72163360  176 te------------------------------------------------------------------------------ 177
gi 88854719  114 ss------------------------------------------------------------------------------ 115
gi 119718456  99 da------------------------------------------------------------------------------ 100
gi 148272427 131 as------------------------------------------------------------------------------ 132
gi 153895520  98 eg------------------------------------------------------------------------------ 99
gi 163841710 114 ap------------------------------------------------------------------------------ 115
gi 169174711 123 ag------------------------------------------------------------------------------ 124
gi 170783102 122 pedaerl------------------------------------------------------------------------- 128
                        170       180       190       200       210       220       230       240
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
Feature 1                                                                                        
1T7D_A       160 vthriltvpiaqdqvgmyyqqpgqqlatwivppgqYFMMGDnrdNSADSRYWgfv------------------------- 214
gi 56962527  100 -------------------------------gktyYKTQGDn-nNVVDEDPIv--------------------------- 120
gi 72163360  178 -------------------------------egivFHTQGDa--NTVPDEPPvp-------------------------- 198
gi 88854719  116 ------------------------------dgsrtFTLQGDn--NDVADELQvl-------------------------- 137
gi 119718456 101 ------------------------------tgqpaFRTKGDa--NDAPDGAMvr-------------------------- 122
gi 148272427 133 ------------------------------dgtrsFTFKGDn--NASPDSLPvt-------------------------- 154
gi 153895520 100 -------------------------------gglaFETQGDa--NEGPDPGLvp-------------------------- 120
gi 163841710 116 ------------------------------ngernFQMQGDa--NNTPDAAAvr-------------------------- 137
gi 169174711 125 -------------------------------asttIQTKGDa--NNGADPWNatmaddhafttva--------viphlgd 163
gi 170783102 129 --------------------------dgwsddrlaIQTKGDn--NPSGDPWIvtigddavwertsvvpflgwpfvwlgdp 180
                        250
                 ....*....|...
Feature 1                     
1T7D_A       215 ----peANLVGRA 223
gi 56962527  121 -----kEQIVGTH 128
gi 72163360  199 -----aADVRGKV 206
gi 88854719  138 -----pIQVVGKL 145
gi 119718456 123 -----tYQIVGER 130
gi 148272427 155 -----pGQIQGEV 162
gi 153895520 121 -----aANLVGAV 128
gi 163841710 138 -----pVQIRGVL 145
gi 169174711 164 airalrSPVVGKV 176
gi 170783102 181 itraiaFAVVGAV 193

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