Final answer:
A deletion upstream from the transcription start site of the trp operon could disrupt RNA polymerase binding, leading to reduced expression of the genes necessary for tryptophan synthesis in E. coli. This would impair the bacteria's ability to synthesize tryptophan when it is not readily available in the environment.
Step-by-step explanation:
In Escherichia coli (E. coli), the synthesis of the amino acid tryptophan is controlled by the trp operon. This operon is a group of genes that are co-regulated and are required for tryptophan biosynthesis.
The operon includes a promoter region where RNA polymerase binds to initiate transcription, an operator sequence where a repressor can bind to prevent transcription, and the structural genes that are expressed to synthesize tryptophan.
A deletion of six nucleotides approximately 35 nucleotides upstream from the transcription start site is likely to be within the promoter region. This deletion could disrupt the binding site for RNA polymerase or other regulatory proteins, potentially affecting the transcriptional initiation of the operon.
If the RNA polymerase binding is compromised, gene expression of the five genes necessary for tryptophan synthesis will decrease, leading to decreased levels of tryptophan synthesis, especially under conditions where tryptophan is not abundant in the environment.