title: Improved membrane protein expression in Lactococcus lactis by fusion to Mistic.
abstract: Difficulty overexpressing (eukaryotic) membrane proteins is generally considered as the major impediment in their structural and functional research. Lactococcus lactis possesses many properties ideal for membrane protein expression. In order to investigate membrane protein expression in L. lactis, we created a novel expression system by introducing Mistic, a short peptide previously identified in Bacillus subtilis, into L. lactis. The potential of this system was demonstrated in the overexpression of a eukaryotic membrane protein (pkjDes4) and a prokaryotic membrane protein (pkjLi), a newly isolated linoleate isomerase from Lactobacillus acidophilus. The expression levels reached up to 4.4 % and 45.2 % for pkjDes4 and pkjLi, respectively, which represented an exceptionally robust ability to overproduce membrane proteins. Moreover, the expressed pkjLi was functional, with its catalysing nature characterized for the first time in this species. Up to 0.852 mg ml(-1) conjugated linoleic acid was obtained during the linoleic acid conversion catalysed by the recombinant lactococcal strains. In summary, we established a membrane protein expression system in L. lactis and examined its functionality. Our results demonstrate that the Mistic chaperoning strategy can be efficiently applied to L. lactis hosts and show its extraordinary capacity to facilitate the high-yield production of intractable membrane proteins.
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan, Shandong Province, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan, Shandong Province, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Kong
authors.affiliation: Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA.|State Key Laboratory of Microbial Technology, Shandong University, Jinan, Shandong Province, China.
authors.forename: Wentao
authors.initials: W
authors.lastname: Kong
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D015870:Gene Expression; D005827:Genetics, Microbial / Q000379:methods; D007779:Lactobacillus acidophilus / Q000235:genetics; D013294:Lactococcus lactis / Q000235:genetics* / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D008967:Molecular Biology / Q000379:methods; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins