DUF1100 UPF0255. The family was split in two. Duf_1100-S with active site (S217 in (GXSXG) D300 H329) as in artni-Q93NG6, and Duf_1100-R with active site (R53, D203, R 272 (in GXRXG)) as in FrsA. The fermentation/respiration switch protein FrsA (product of the yafA gene in E. Coli (ecoli-yafa)(vibvy-y856) binds the dephosphorylated form of glucose-specific enzyme IIAGl the interaction increases the glucose fermentation under oxygen-limited conditions. FrsA is a pyruvate decarboxylase (Lee et al.)(In Scop 2,6-dihydropseudooxynicotine hydrolase). Thus there are two functions and two different active sites in this family (nucleophile elbow: GXSXG in hydrolase, GXRXG in decarboxylase). However (Kellett et al.) showed computational, structural, and kinetic evidence that Vibrio vulnificus FrsA is not a cofactor-independent pyruvate decarboxylase. Other members of this family are still uncharacterised