Orotate transporter encoding maker genes

Abstract

A recombinant marker gene encoding an orotate transporter polypeptide comprising an amino acid sequence at least 60% identical to SEQ ID NO: 2, a polynucleotide construct comprising at least one copy of the recombinant marker gene, a cell comprising at least one exogenous copy of the marker gene, and a method of selecting or identifying a cell comprising at least one copy of the recombinant marker gene, and / or selecting or identifying a cell which has been cured of the recombinant marker gene.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a pioneering new class of orotate transporter polypeptide encoding marker genes. One orotate transporter of the invention is derived from a Lactococcus lactis strain, and is encoded by the ysbC gene. It is demonstrated herein that the orotate transporter gene is suitable to be used as a versatile non-antibiotic marker gene, both in selection, counter-selection, screening, and bi-directional selection protocols. BACKGROUND [0002] A putative gene, denoted ysbC, was previously identified by genome sequencing of a Lactococcus lactis strain, but the gene was not annotated, and no function of the predicted encoded polypeptide was identified (WO 200177334, Bolotin et al., 2001, The Complete Genome Sequence of the Lactic Acid Bacterium Lactococcus lactis ssp. Lactis IL1403, Genome Res. 11:731). The amino acid sequence of the predicted YsbC protein is available from the database GeneSeqP, accession number: ABB55104. [0003] There ...

AI Technical Summary

Benefits of technology

[0035] Multiple alignments of protein sequences may be made using “ClustalW” (Thompson, J. D., Higgins, D. G. and Gibson, T. J. (1994) CLUSTAL W: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, positions-specific gap penalties and weight matrix choice. Nucleic Acids Research, 22:4673-4680). Multiple alignment of DNA sequences may be done using the protein alignment as a template, replacing the amino acids with the corresponding codon from the DNA sequence. Allelic Variant

[0074] The vectors of the present invention preferably contain one or more selectable markers which permit easy selection of transformed cells. A selectable marker is a gene the product of which provides for biocide or viral resistance, resistance to heavy metals, prototrophy to auxotrophs, and the like.

[0078] For integration into the host cell genome, the vector may rely on the nucleotide sequence encoding the polypeptide or any other element of the vector for stable integration of the vector into the genome by homologous or nonhomologous recombination. Alternatively, the vector may contain additional nucleotide sequences for directing integration by homologous recombination into the genome of the host cell. The additional nucleotide sequences enable the vector to be integrated into the host cell genome at a precise location(s) in the chromosome(s). To increase the likelihood of integration at a precise location, the integrational elements should preferably contain a sufficient number of nucleotides, such as 100 to 1,500 base pairs, preferably 400 to 1,500 base pairs, and most preferably 800 to 1,500 base pairs, which are highly homologous with the corresponding target sequence to enhance the probability of homologous recombination. The integrational elements may be any sequence that is homologous with the target sequence in the genome of the host cell. Furthermore, the integrational elements may be non-encoding or encoding nucleotide sequences. On the other hand, the vector may be integrated into the genome of the host cell by non-homologous recombination.

Problems solved by technology

In particular, there is concern about the cultivation of recombinant cells carrying antibiotic genetic markers, mostly due to the perceived potential risk for lateral transfer of such markers into nature.

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