The correct answer is option 1: sequencing the genome of E. coli. In recent scientific advancements, there has been a significant breakthrough in the field of genetics. Genome sequencing refers to the process of determining the complete DNA sequence of an organism. E. coli is a commonly studied bacterium and understanding its genetic makeup has great implications in various fields like medicine, agriculture, and biotechnology.

Option 2, sequencing alone, is not specific enough. It is important to identify what is being sequenced, and in this case, it is the genome of E. coli.

Option 3, understanding the genetic codes, is a broad term that can include various aspects of genetics. However, the specific breakthrough being referred to in the question is the sequencing of the E. coli genome.

Option 4, understanding the protein structure, is unrelated to the breakthrough mentioned in the question. Protein structure typically involves studying the three-dimensional arrangement of amino acids in proteins, which is important for understanding their function and designing drugs. However, it is not the focus of the breakthrough mentioned here.

Therefore, the correct answer is option 1, sequencing the genome of E. coli, as it represents the latest scientific breakthrough causing tremors globally.