cd06529

S24_LexA-like

CDD entry
Member databaseCDD
CDD typedomain
Short nameS24_LexA-like
SetPeptidase_S24_S26

Description

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.
[4, 5, 3, 1, 2, 6, 7, 8]

References

1.Converting a DNA damage checkpoint effector (UmuD2C) into a lesion bypass polymerase (UmuD'2C). Ferentz AE, Walker GC, Wagner G. EMBO J. 20, 4287-98, (2001). View articlePMID: 11483531

2.Structure of a hyper-cleavable monomeric fragment of phage lambda repressor containing the cleavage site region. Ndjonka D, Bell CE. J. Mol. Biol. 362, 479-89, (2006). View articlePMID: 16934834

3.Crystal structure of LexA: a conformational switch for regulation of self-cleavage. Luo Y, Pfuetzner RA, Mosimann S, Paetzel M, Frey EA, Cherney M, Kim B, Little JW, Strynadka NC. Cell 106, 585-94, (2001). View articlePMID: 11551506

4.RecA-dependent cleavage of LexA dimers. Giese KC, Michalowski CB, Little JW. J. Mol. Biol. 377, 148-61, (2008). View articlePMID: 18234215

5.Aeons of distress: an evolutionary perspective on the bacterial SOS response. Erill I, Campoy S, Barbe J. FEMS Microbiol. Rev. 31, 637-56, (2007). View articlePMID: 17883408

6.Cleavage of LexA repressor. Little JW, Kim B, Roland KL, Smith MH, Lin LL, Slilaty SN. Meth. Enzymol. 244, 266-84, (1994). View articlePMID: 7845214

7.LexA represses CTXphi transcription by blocking access of the alpha C-terminal domain of RNA polymerase to promoter DNA. Quinones M, Kimsey HH, Ross W, Gourse RL, Waldor MK. J. Biol. Chem. 281, 39407-12, (2006). View articlePMID: 17046810

8.A LexA-related protein regulates redox-sensitive expression of the cyanobacterial RNA helicase, crhR. Patterson-Fortin LM, Colvin KR, Owttrim GW. Nucleic Acids Res. 34, 3446-54, (2006). View articlePMID: 16840531

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