Dartmouth College researchers have discovered that the arrangement of genes, or 'gene syntax,' within a plasmid significantly influences gene expression. This finding highlights the importance of gene placement, similar to how word order affects the meaning of a sentence.
Gene Syntax Matters
The study, published in the Journal of Biological Engineering, reveals that altering gene syntax affects the movement of transcriptional machinery along DNA, the interaction between replication and transcription, and the variability in gene expression. Researchers systematically analyzed the impact of gene order and orientation on plasmids, which are small, circular DNA molecules often found in bacteria and used to study gene function.
Experimental Design and Results
The researchers constructed plasmids with fluorescent reporter genes in different orders and orientations, while keeping promoters and ribosomal binding sites identical. The results demonstrated that changes in gene syntax led to significant differences in expression levels and variability. For instance, the expression of green fluorescent protein (GFP) varied by more than 1.8-fold depending on its placement. Genes aligned in the same direction as the plasmid's origin of replication exhibited higher expression, while tandem gene orientation led to stronger expression, and divergent orientation suppressed gene activity.
Implications for Synthetic Biology
Switching gene order also altered expression levels, confirming that both position and orientation influence gene output. These findings demonstrate that gene syntax is a crucial design element. By treating gene syntax as a tunable variable, synthetic biologists and bioengineers can improve the predictability and precision of genetic tools, paving the way for optimized genetic engineering techniques and more efficient gene circuits for various applications.