nBlog 2007-11-08

It's just 3-bp. But still...!

The majority of mycobacterial plasmid vectors utilize the pAL5000 origin of replication. In the journal Tuberculosis 87:481-488 (2007), William R. Bourn et al. reported the isolation of a high-copy-number mutant of a pAL5000-based vector. The mutant carries a 3-bp deletion in the repA gene, which results the deletion of an alanine residue in the C-terminal end of the RepA replication protein.

I say the obvious, but increased expression of gene is often brought by increased copy-number of the gene (gene dosage effect). Cloning a gene into a high-copy-number vector is one of the most commonly used strategy for strong expression of the gene. So, it is highly desirable that such vector is available in Nocardia species. Dr. Bourn said "Whatever the mechanism, the isolation of this pAL5000 based high-copy-number replicon will provide a valuable tool for mycobacterial researchers, especially since the many pAL5000-based vectors that already exist can be converted to a high-copy-number phenotype by simple recombinant DNA methods". I completely agree with him and I have started to construct the high-copy-number version of pNV vectors, which will be called pNV118 and pNV119. I will announce if I was successful in constructing them.