Abstract
Eukaryotic membrane proteins are often difficult to produce in large quantities, which is a significant obstacle for further structural and biochemical investigation. Lactococcus lactis has several properties that are ideal for enhanced expression of eukaryotic membrane proteins. In this article, a novel lactococcal vector was constructed, by inserting a green fluorescent protein (GFP) sequence into the vector pNZ8148. The resulting vector pKj-gfp was applied to the overexpression of an elongase-GFP fusion in L. lactis. After adding nisin, the expression of the fusion was confirmed via microscopy, the conditions were optimized by fluorescent spectroscopy, and the location of the fusion was monitored through in-gel fluorescence, indicating that the fusion was directed into the cytoplasmic membrane and no degradation was observed. The ELKJ-GFP fusion accounted for ~15% of the total membrane proteins using PDQuest software. These results indicate that the lactococcal system can be used for the overproduction and convenient detection of eukaryotic membrane proteins.




Similar content being viewed by others
Explore related subjects
Discover the latest articles and news from researchers in related subjects, suggested using machine learning.References
de Ruyter PG, Kuipers OP, de Vos WM (1996) Controlled gene expression systems for Lactococcus lactis with the food-grade inducer nisin. Appl Environ Microbiol 62:3662–3667
Drew D, Lerch M, Kunji E et al (2006) Optimization of membrane protein overexpression and purification using GFP fusions. Nat Methods 3:303–313
Drew D, Slotboom DJ, Friso G et al (2005) A scalable, GFP-based pipeline for membrane protein overexpression screening and purification. Protein Sci 14:2011–2017
Drew DE, von Heijne G, Nordlund P et al (2001) Green fluorescent protein as an indicator to monitor membrane protein overexpression in Escherichia coli. FEBS Lett 507:220–224
Fernandez de Palencia P, Nieto C, Acebo P et al (2000) Expression of green fluorescent protein in Lactococcus lactis. FEMS Microbiol Lett 183:229–234
Holo H, Nes IF (1989) High-frequency transformation, by electroporation, of Lactococcus lactis subsp. cremoris grown with glycine in osmotically stabilized media. Appl Environ Microbiol 55:3119–3123
Kleerebezem M, Beerthuyzen MM, Vaughan EE et al (1997) Controlled gene expression systems for lactic acid bacteria: transferable nisin-inducible expression cassettes for Lactococcus, Leuconostoc, and Lactobacillus spp. Appl Environ Microbiol 63:4581–4584
Kunji ER, Chan KW, Slotboom DJ et al (2005) Eukaryotic membrane protein overproduction in Lactococcus lactis. Curr Opin Biotechnol 16:546–551
Kunji ER, Slotboom DJ, Poolman B (2003) Lactococcus lactis as host for overproduction of functional membrane proteins. Biochim Biophys Acta 1610:97–108
Monne M, Chan KW, Slotboom DJ et al (2005) Functional expression of eukaryotic membrane proteins in Lactococcus lactis. Protein Sci 14:3048–3056
Newstead S, Kim H, von Heijne G et al (2007) High-throughput fluorescent-based optimization of eukaryotic membrane protein overexpression and purification in Saccharomyces cerevisiae. Proc Natl Acad Sci USA 104:13,936–13,941
Oddone GM, Lan CQ, Rawsthorne H et al (2007) Optimization of fed-batch production of the model recombinant protein GFP in Lactococcus lactis. Biotechnol Bioeng 96:1127–11238
Sullivan KF (1999) Enlightening mitosis: construction and expression of green fluorescent fusion proteins. Methods Cell Biol 61:113–135
Waldo GS, Standish BM, Berendzen J et al (1999) Rapid protein-folding assay using green fluorescent protein. Nat Biotechnol 17:691–695
Wallin E, von Heijne G (1998) Genome-wide analysis of integral membrane proteins from eubacterial, archaean, and eukaryotic organisms. Protein Sci 7:1029–1038
Niu Y, Kong J, Fu L, Yang J, Xu Y (2008) Identification of a novel C20-elongase gene from the marine microalgae Pavlova viridis and its expression in Escherichia coli. Marine Biotechnol (in press)
Acknowledgments
We thank Professor Jan-Willem L. de Gier for providing the pWaldo-gfpd/gfpe plasmids. The authors thank Dr. Pamela Holt for editing the manuscript. Financial support for this work was provided by the National Science Foundation of China (NSFC;, grant No. 30370035) and the HI-tech research and development program of China (grant Nos. 2006AA10Z321 and 2006AA10Z344).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Niu, Y., Kong, J. & Xu, Y. A Novel GFP-Fused Eukaryotic Membrane Protein Expression System in Lactococcus lactis and Its Application to Overexpression of an Elongase. Curr Microbiol 57, 423–428 (2008). https://doi.org/10.1007/s00284-008-9223-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00284-008-9223-8
