Impacts of a DUF2207 Family Protein on Stress Tolerance Responses and Biofilm Formation.

Locus SMU.243 in was annotated as a member of the DUF2207 family proteins highly conserved in all bacteria but with unknown function. To investigate its role in physiology, a SMU.243-deficient mutant was constructed using allelic exchange mutagenesis, and the impacts of SMU.243 deletion on bacterial growth, stress tolerance response, and biofilm formation were analyzed. Compared to the wild-type UA159, lacking SMU.243 displayed a reduced growth rate and a reduced overnight culture density ( 0.01) when grown at low pH and in the presence of methyl viologen. Relative to the parent strain, the deficient mutant also had a reduced survival rate following incubation in a buffer of pH 2.8 ( < 0.01) and in a buffer containing hydrogen peroxide at 58 mM after 60 min ( < 0.001) and had a reduced capacity in biofilm formation especially in the presence of sucrose ( < 0.01). To study any ensuing functional/phenotypical links between SMU.243 and , which is located immediately downstream of SMU.243 and encodes an undecaprenyl pyrophosphate phosphatase involved in recycling of carrier lipid undecaprenyl phosphate, a deficient mutant was generated using allelic exchange mutagenesis. Unlike the SMU.243 mutant, deletion of affected cell envelope biogenesis and caused major increases in susceptibility to bacitracin. In addition, two variant morphological mutants, one forming rough colonies and the other forming mucoid, smooth colonies, also emerged following the deletion of . The results suggest that the SMU.243-encoded protein of the DUF2207 family in plays an important role in stress tolerance response and biofilm formation, but unlike the downstream , does not seem to be involved in cell envelope biogenesis, although the exact roles in ' physiology awaits further investigation.