In B. subtilis, one small SOS response operon under the control of LexA, the yneA operon, is comprised of three genes: yneA, yneB, and ynzC [1]. This family consists of several short, hypothetical bacterial proteins of unknown function. These proteins are mainly found in gram-positive firmicutes. Structures show that the N-terminus is composed of two alpha helices forming a helix-loop-helix motif. The structure of ynzC from B. subtilis forms a trimeric complex [2]. Structural modelling suggests this domain may bind nucleic acids [3]. This family is also known as UPF0291.

1: Identification of a protein, YneA, responsible for cell division suppression during the SOS response in Bacillus subtilis. Kawai Y, Moriya S, Ogasawara N; Mol Microbiol. 2003;47:1113-1122. PMID:12581363

2: Solution NMR structure of the SOS response protein YnzC from Bacillus subtilis. Aramini JM, Sharma S, Huang YJ, Swapna GV, Ho CK, Shetty K, Cunningham K, Ma LC, Zhao L, Owens LA, Jiang M, Xiao R, Liu J, Baran MC, Acton TB, Rost B, Montelione GT; Proteins. 2008;72:526-530. PMID:18431750

3: Ab Initio Modeling Led Annotation Suggests Nucleic Acid Binding Function for Many DUFs. Rigden DJ; OMICS 2011;0:0-0. PMID:21348639