Characterization of a promoter for heterologous protein production.

Constitutively active promoter elements for heterologous protein production in are scarce. Here, the promoter of the gene cluster from NZ3900 is described. This promoter was cloned upstream of an enhanced green fluorescent protein, GFPmut3a, and transformed into Transformants produced up to 13.5 μg of GFPmut3a per milliliter of log phase cells. Addition of cellobiose further increased the production of GFPmut3a by up to two-fold when compared to glucose. Analysis of mutations at two specific positions in the promoter showed that a 'T' to 'G' mutation within the -35 element resulted in constitutive expression in glucose, while a 'C' at nucleotide 7 in the putative site enhanced promoter activity in cellobiose. Finally, this promoter is capable of mediating protein expression in and Nissle 1917, suggesting the potential for future biotechnological applications of this element and its derivatives.