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Genes are the stretches of DNA that code for specific proteins. While some genes are read most of the time, other genes are activated only in times of need, for example, to digest a specific molecule or respond to a specific kind of stress like cold or starvation.
The main steps involved in gene expression (or the process of turning a gene into a protein) can be broken down into two major parts. The first is transcription, which describes the process of changing DNA into RNA. The second step is translation, which uses the RNA template to create the sequence of amino acids that make up the corresponding protein. Here at the lab, we are concerned with a special enzyme called RNA polymerase (RNAP) which binds to the beginning of the gene and begins to read it during transcription, all the while making a copy of it in the form of RNA.
Many questions about this process have puzzled scientists for a long time: how does the RNAP find the beginning of the gene among all the possible genes in the chromosome? How is this process regulated? How is RNAP activity at a given gene turned off and on?
Gene expression is often regulated by proteins that bind near and on the gene sequence and affect the activity of the RNA polymerase enzyme. We are trying to find out what they are and how they do their job at the right place and at the right time.
The bacterial RNA polymerase enzyme bound to the DNA.
The sigma subunit (in red) is the part of the protein responsible for binding to the specific sequence of the gene's promoter region found at the transcription initiation site.
You can go to this Scitable page to find more information about gene expression and its regulation in response to environmental changes.
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