>gnl|CDD|119397 cd06529, S24_LexA-like, 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.. Length = 81

 Score = 49.1 bits (118), Expect = 8e-07
 Identities = 18/76 (23%), Positives = 38/76 (50%), Gaps = 1/76 (1%)

Query: 143 QDTSMLPLYRKGDILILNSAIQVNCGDRLLIKPRTGDIVAKVLISRRGRSIDLMSLNCCY 202
           +  SM P    GD+++++ +     GD ++ +   G++  K L  R G  + L+S N  Y
Sbjct: 6   KGDSMEPTIPDGDLVLVDPSDTPRDGDIVVAR-LDGELTVKRLQRRGGGRLRLISDNPAY 64

Query: 203 PVDTVEMSDIEWIARI 218
           P   ++  ++E +  +
Sbjct: 65  PPIEIDEEELEIVGVV 80