1

Mary Stathos December 7, 2014

Tryptophan repressor’s ability to change conformation allows for ideal binding conditions to trp operon and others

2

1TRO INTRODUCTION 1TRO is the Protein Data Bank code for the tryptophan repressor protein, which is the repressor the tryptophan operon, responsible for the synthesis of tryptophan. The synthesis of tryptophan is a biologically expensive process that requires no only the trp operon, but additional energy from four other pathways in the cell. Because this is such a taxing process, it is vital for the trp repressor to have a strong affinity to bind to the operon in a way that is effective and stable. The complex structure of the repressor offers a unique way of binding to the operon and to L-­‐tryptophan in a way that is effective for the molecule. The repressor is able to undergo changes in its structure and conformation in order to allow the binding of L-­‐tryptophan, as well as binding to the DNA. This increases the stability of the protein and allows it to bind more effectively, repressing the operon in order to conserve energy in the cell.

PDB The Protein Data Bank is a resource that contains information about the 3D structures of proteins, nucleic acids and complex assemblies in order to help students and researchers get a wider understanding of biomedicine. It is the only worldwide depository for information on 3D structures of these large biological molecules. It was first established in 1971 and is growing exponentially. In 1999, PDB released its 10,000th structure. However, as of 2011, more than 77,000 structures exist in the archive.

OPERON

The term operon was proposed in 1960 by the French Academy of Sciences,

suggesting that all genes are controlled by repression. It was later discovered that this process is far more complex (Santillán). An operon is a set of genes that exist together. On

3

the operon, there is a promoter and operator sequence that allows the transcription of the genes to be controlled (Stevenson). Bacteria use these operons as means of organization. All the genes in the operon are turned on and off together, which is used to be able to adapt rapidly to environmental changes. There are many different mechanisms that regulate this gene expression and they vary from operon to operon