Conserved Protein Domain Family
S24_LexA-like

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cd06529: S24_LexA-like 
Click on image for an interactive view with Cn3D
Peptidase S24 LexA-like proteins are involved in the SOS response leading to the repair of single-stranded DNA within the bacterial cell. This family includes: the lambda repressor CI/C2 family and related bacterial prophage repressor proteins; LexA (EC 3.4.21.88), the repressor of genes in the cellular SOS response to DNA damage; MucA and the related UmuD proteins, which are lesion-bypass DNA polymerases, induced in response to mitogenic DNA damage; RulA, a component of the rulAB locus that confers resistance to UV, and RuvA, which is a component of the RuvABC resolvasome that catalyzes the resolution of Holliday junctions that arise during genetic recombination and DNA repair. The LexA-like proteins contain two-domains: an N-terminal DNA binding domain and a C-terminal domain (CTD) that provides LexA dimerization as well as cleavage activity. They undergo autolysis, cleaving at an Ala-Gly or a Cys-Gly bond, separating the DNA-binding domain from the rest of the protein. In the presence of single-stranded DNA, the LexA, UmuD and MucA proteins interact with RecA, activating self cleavage, thus either derepressing transcription in the case of LexA or activating the lesion-bypass polymerase in the case of UmuD and MucA. The LexA proteins are serine proteases that carry out catalysis using a serine/lysine dyad instead of the prototypical serine/histidine/aspartic acid triad found in most serine proteases. LexA sequence homologs are found in almost all of the bacterial genomes sequenced to date, covering a large number of phyla, suggesting both, an ancient origin and a widespread distribution of lexA and the SOS response.
Statistics
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PSSM-Id: 119397
View PSSM: cd06529
Aligned: 418 rows
Threshold Bit Score: 40.62
Threshold Setting Gi: 58040792
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.

Sequence Alignment
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Format: Row Display: Color Bits: Type Selection:
                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
Feature 1                #                                              #                        
2HNF_A        45 FWLEVEGNSMttptgsktsfpDGMLILVDpeqa----vepGDFCIARLGgdEFTFAKLIrds----gqvFLQPLNp---Q 113
gi 116749299 143 FLIRVQGDAMlpt------vnQGDVALVDsdeaermrvlsGRIYLVVLPdgATAFRRLAlsggrdcprlVCLSDNt--aA 214
gi 68249874  229 AMITMFNESMspv------inKKDLMFVDttck---qyagEGIYLFVMNn-ELYVRRLYqtps---gvlNAVAENe--rV 293
gi 78357989  140 QVFRVDATSMepl------iaKGAFVCLDtqqk---siisGELYGVFIPyeGIAIRRVFldaq--nqrfILRSENp---A 205
gi 120602096 152 VCVRVSQDSMapl------lhVGDYVIIDradcvvteqghGNIFLVNDPqdGPTIKRARiqstptstvlFCYCDNv---R 222
gi 94970418  148 RCMRVRGDSMapi------vdDGYIVAVDtserd-prklvESMVAVSDPesGCTIKWLRqagr---arfLLVPQHts-pR 216
gi 76808544  198 AVVRIEDDLMapt------fqRRDNVLVDmgyq---hkpgNGLYALRLEd-SIVVRRTQklss---gklRILCENe---N 261
gi 120613133 146 IAIAVGDDSMqps------lhPGDVVAVDtrdp---spadGQVFVVDYEg-ACLVRRVVrds----gawWLAAENa--lR 209
gi 120613182 141 LAIRVRGCGMeps------iqAGDIVVVNtsdt---tlrdGQVFAINGFg-EVLLRRAQrdd----grwWISCDNpdqaR 206
gi 91200019  120 YLFHVKDDSMept------lkNGDVVIVDkknn---vldrDGLYLLRTEgaAAFIKRVQrlpg---gslHLLCDNa---T 184
                         90       100
                 ....*....|....*....|...
Feature 1                               
2HNF_A       114 YPMIPCne------sCSVVGKVI 130
gi 116749299 215 FRPFEFald---pgkPLRNHILG 234
gi 68249874  294 GSSFEId-------dLSRLNVLG 309
gi 78357989  206 LPEQYLpl------gKHHSSIVG 222
gi 120602096 223 IPPSFIqipqdddnyLSHGVLGG 245
gi 94970418  217 HNPIVLdp------kEEGWRIIG 233
gi 76808544  262 YPPDEIrpd----enEFDFEIVG 280
gi 120613133 210 FPRKQLt--------APSARLVG 224
gi 120613182 207 YPRKAWa--------EPDCIPIG 221
gi 91200019  185 YKPIEAkta---qieNGDIVIVG 204

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