Complementation of a temperature sensitiveEscherichia coli rpoDmutation usingLactobacillussigma factors

Housekeeping sigma factors in the σ 70 family, as components of the RNA polymerase holoenzyme, are responsible for regulating transcription of genes related to vegetative growth. While these factors are well understood in model organisms such as Escherichia coli and Bacillus subtilis , little experimental work has focused on the sigma factors in members of the Lactobacillus genus such as Lactobacillus brevis and Lactobacillus plantarum . This study evaluates the ability of putative σ 70 proteins from L. brevis ( ) and L. plantarum ( ) to complement a temperature sensitive mutation in the E. coli 285c σ 70 protein. This report is the first to show that these heterologous sigma factors were capable of restoring the viability of E. coli 285c for growth at 40-43.5 ° C , indicating the and are capable of initiating transcription in a complex with the E. coli 285c RNA polymerase. These heterologous sigma factors may therefore be useful for improving biochemical knowledge of the sigma factor family or for use in the expression of hetereologous genomic libraries.