Regulated Recombinant Protein Production in the Antarctic Bacterium Pseudoalteromonas haloplanktis TAC125

Abstract

This review reports results from our laboratory on the development of an effective inducible expression system for the homologous/heterologous protein production in cold-adapted bacteria. Recently, we isolated and characterized a regulative genomic region from Pseudoalteromonas haloplanktis TAC125; in particular, a two-component regulatory system was identified. It is involved in the transcriptional regulation of the gene coding for an outer membrane porin (PSHAb0363) that is strongly induced by the presence of L: -malate in the growth medium.We used the regulative region comprising the two-component system located upstream the PSHAb0363 gene to construct an inducible expression vector - named pUCRP - under the control of L: -malate. Performances of the inducible system were tested using the psychrophilic β-galactosidase from P. haloplanktis TAE79 as model enzyme to be produced. Our results demonstrate that the recombinant cold-adapted enzyme is produced in P. haloplanktis TAC125 in good yields and in a completely soluble and catalytically competent form. Moreover, an evaluation of optimal induction conditions for protein production was also carried out in two consecutive steps: (1) definition of the optimal cellular growth phase in which the gene expression has to be induced; (2) definition of the optimal inducer concentration that has to be added in the growth medium.