This family consists of several hypothetical bacterial proteins of around 180 residues in length which are often known as YaeQ. YaeQ is homologous to RfaH, a specialised transcription elongation protein. YaeQ is known to compensate for loss of RfaH function [1].

1: A gene, yaeQ, that suppresses reduced operon expression caused by mutations in the transcription elongation gene rfaH in Escherichia coli and Salmonella typhimurium. Wong KR, Hughes C, Koronakis V; Mol Gen Genet 1998;257:693-696. PMID:9604894

2: Sequence, structure and functional diversity of PD-(D/E)XK phosphodiesterase superfamily. Steczkiewicz K, Muszewska A, Knizewski L, Rychlewski L, Ginalski K; Nucleic Acids Res. 2012;40:7016-7045. PMID:22638584