Lactose Bends the Protein

by Greg Crowther

This song, written for a guest lecture at Evergreen State College, addresses the lac operon. In particular, it focuses on how lactose (or, technically, a derivative called allolactose) allosterically regulates the repressor protein encoded by the lacI gene. The word "bends" is repeatedly sung in a pitch-bending manner to emphasize the alteration (bending) of the repressor protein's 3-dimensional shape.

What happens to repressors when the lactose binds?
(What happens to repressors when the lactose binds?)
What fascinating data did the Frenchmen find?
(What fascinating data did the Frenchmen find?)

Lactose bends the protein,
Changing its 3D shape;
Bends the protein,
And tweaks its energetic landscape.

Lactose bends the protein
'Til it lets go of the DNA;
Bends the protein,
And gets transcription underway.

• MP3 (demo)

• sheet music (with melody play-back)

Songs like this one can be used during class meetings and/or in homework assignments. Either way, the song will be most impactful if students DO something with it, as opposed to just listening.

An initial, simple follow-up activity could be to answer the study questions below. A more extensive interaction with the song might entail (A) learning to sing it, using an audio file and/or sheet music as a guide, and/or (B) illustrating it with pictures, bodily poses, and/or bodily movements. The latter activity could begin with students identifying the most important or most challenging content of the song, and deciding how to illustrate that particular content.

(1) Who are the Frenchmen to which the song refers?

(2) In the context of protein structure, what is an energetic landscape?

(3) To what specific region of DNA does the repressor protein bind?

(4) How does the repressor's dissociation from the DNA enable transcription of the lac operon?