Expression of the sweet-tasting plant protein brazzein in Escherichia coli and Lactococcus lactis: a path toward sweet lactic acid bacteria

• Published in: Applied microbiology and biotechnology 2006-11, Vol.73 (1), p.158-165
• Main Authors: Berlec, Aleš, Jevnikar, Zala, Majhenič, Andreja Čanžek, Rogelj, Irena, Štrukelj, Borut
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Bacteria; Base Sequence; Biological and medical sciences; Biotechnology; E coli; Escherichia coli; Escherichia coli - genetics; Escherichia coli - metabolism; Fermentation; Fundamental and applied biological sciences. Psychology; Gene Expression; Lactococcus lactis; Lactococcus lactis - genetics; Lactococcus lactis - metabolism; Microbiology; Molecular Sequence Data; Plant Proteins - biosynthesis; Plant Proteins - chemistry; Plant Proteins - genetics; Recombinant Proteins - biosynthesis; Recombinant Proteins - genetics; Sweetening Agents; Taste
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-006-0438-y

Brazzein is an intensely sweet-tasting plant protein with good stability, which makes it an attractive alternative to sucrose. A brazzein gene has been designed, synthesized, and expressed in Escherichia coli at 30 °C to yield brazzein in a soluble form and in considerable quantity. Antibodies have been produced using brazzein fused to His-tag. Brazzein without the tag was sweet and resembled closely the taste of its native counterpart. The brazzein gene was also expressed in Lactococcus lactis, using a nisin-controlled expression system, to produce sweet-tasting lactic acid bacteria. The low level of expression was detected with anti-brazzein antibodies. Secretion of brazzein into the medium has not led to significant yield increase. Surprisingly, optimizing the codon usage for Lactococcus lactis led to a decrease in the yield of brazzein.