Selected from the Diaries of S. cerevisiae
Transcribed by Wenying Shou*
This was written nearly 20 years ago. Having just finished my graduate thesis at Caltech, I decided to enter the Science-Amersham competition. The competition required an essay on graduate work. I wrote a formal essay (https://www.sciencemag.org/site/feature/data/pharmacia/2002/shou.xhtml), and showed it to my thesis advisor Raymond Deshaies. He was unimpressed, commenting that the essay lacked creativity. Shortly afterwards, this yeast diary essay was born. I had so much fun writing it. I ended up winning the 2002 Science-Amersham North America prize. However, the Science magazine’s link to the yeast diary is no longer active. Thus, I am posting it here.
Reading the essay again after two decades, I realize that it could have been written better. However, except for adding images and links, I have kept its original flavor.
Bred to eat and divide, we budding yeast cells are nearly perfect by now. We much prefer being left alone, but unfortunately biologists, thinking that we are similar to their own cells, fall hopelessly in love with us.
Uh-oh, here comes another one of them! She stares intensely at us — we know that awful look — what does she want?
She is shutting down our Cdc15! What a fool — doesn’t she realize that without it, we can’t exit mitosis and will die without forming a colony?
A few of us have miraculously escaped death. Unfortunately, we fail to escape her. She calls us tab which stands for ‘telophase arrest bypass’ mutants in her strange little language. She must have devious purposes for us!
After comparing ourselves, we see her scheme: by completely removing Cdc15, mutations upstream of CDC15 are weeded out. Taking shortcuts? You just wait . . .
Her complaints, impossible not to be overheard, were initially delicious. “What am I working on? The same bypass mutants . . . so many of them! Oh, no; no insights yet. It takes me forever just to assign them to linkage groups. God only knows if any of them will lead to my breakthrough!”
After many repetitions (with insignificant variations), we can’t help wondering what right she has to complain? It is she who forced us into this game!
Allow me to introduce myself — I am the net1–1 tab mutant. I will write in boldface only, as I am too proud to settle for anything else. Despite being robbed of Cdc15, I still manage to sneak out of mitosis because I have crippled my Net1, which normally blocks mitotic exit until Cdc15 becomes active. Unlike other grumpy tabs, I have set less harsh traps for her. Why? I like keeping her hooked: if I am too difficult, she will give up on me too soon, but if I am too easy, she will solve my puzzle too soon. Besides, I won’t mind my share of glory if she manages to pull this off . . .
After a few trials, she figured out what NET1 encodes. She does not seem to be excited, however — “Net1 has no sequence motifs — what the heck is it doing?”
Her advisor, an Olympic telephone-e-mail biathlon champion, exclaims, “Guess what? Our collaborators did a two-hybrid screen. The Cdc14 bait caught Net1!” Must we now also relinquish Cdc14 — the protein phosphatase that delivers us all out of mitosis?
She is already onto the next question — “Cdc14 promotes and Net1 prevents mitotic exit. Cdc14 and Net1: who inhibits whom?” How can she not smile even once? Is she driven more by ambition than by the fun of playing with me?
We are distraught at how thoughtless she and her colleagues continue to be. Sticking tags onto Net1 and Cdc14 is moderately tolerable. But forcing Cdc14 to work on radioactive substrates? Interrogating Net1 and associates with “mass spectrometry” — whatever that is . . .
She and her student conclude “Net1 inhibits Cdc14.” We are annoyed, but at least she paid a handsome price and it was gratifying to see her gasping with anxiety as she read the scintillation counter.
Mass spectrometry threatens to reveal more of our secrets.
But listen to her — “Net1 associates with Cdc14 — no surprise . . . and Sir2! Sir2 is merely a transcription silencer that sits at the nucleolus, the telomeres, and the silent mating type loci. Cells exit mitosis perfectly well without it. Why Sir2? Nonsense!”
Perhaps, we should not worry after all — when secrets are exposed, she closes her eyes and complains more . . .
Her prying eyes saw Net1 in our nucleoli, where we prepare ribosomes. Did Sir2 lead her there? The same misfortune befell our friends in Boston. She wonders, out loud, “Is Cdc14 in the nucleolus too?”
It does not look too encouraging for us, but we still have plenty of ways to torture her.
She stares at us as we stare back at her through the microscope lens. Suddenly, she dashes out of the darkroom, calls her advisor in, and says, “Take a look: Cdc14 is green and mitotic spindles are red.”
After a short pause, he cries out, “I can’t believe my eyes!”
We wild-type interphase cells with stout spindles are actually in the picture, our Cdc14 snuggled into the crescent nucleolar cradle. But our sisters, dancing out of mitosis, steal the spotlight! Look at them — how gracefully they extend their spindles long and swirl their skirts of Cdc14 open!
She butts in with great excitement, “Cdc14 is usually locked up and shut off in the nucleolus by Net1. As cells march through anaphase with elongating spindles, Cdc15 is activated, which allows Cdc14 to escape Net1 and to promote mitotic exit. In net1–1, Net1 weakens; thus Cdc14 can flee the nucleolus and cells can exit mitosis without Cdc15.”
This is the first time that I remember seeing her smiling at me, the esteemed net1–1. Has she finally started to enjoy me — when the game is almost over?
We tabs have done a lot for her, but she is snooping around our nucleoli to fish for her next paper even before finishing the current one — shameless greed!
I am actually happy that she has not dropped the game with me. She inquires, “Why are you sicker than TAB6?” I answer softly, my voice inaudible, “My RNA Pol I under-performs and my nucleolus collapses, all because I had to harm my Net1 to play the game with you!”
They have publicly named my Net1/Cdc14/Sir2 complex “RENT.” Maybe someday I will become a star on Broadway . . .
Thank heavens — we get a day off from her quest for the ‘RENT disassemblase,’ because she chooses to practice her meeting talk: “Even more important, the nucleolus may serve an unappreciated role as a sequestration center: Like Cdc14, some of the many proteins that localize to the nucleolus may not act solely (or even primarily) in the nucleolus, but may be stockpiled there in anticipation of their eventual release . . .”
Very boring, at least when she recites from her script. However, it is exhilarating to find my name, net1–1, in boldface and colored, on the slides!
After saying good-bye to her labmates, she took me out of the cold room and whispered “I’ll miss you.” Even before I had a chance to respond, she had already flushed me down the drain!
Farewell, the game.
She has, against our wishes, dedicated this selection of our diaries to her advisor R. J. Deshaies (Caltech). In addition, we protest the various contributions to her side of the game from C. Baskerville, E. Traverso, and H. Charbonneau (Purdue); A. and A. Shevchenko (EMBL at Heidelberg); G. Hoppe and D. Moazed (Harvard); J. Keener and M. Nomura (UC Irvine); S. Chen, M. Huddleston, R. Annan, and S. Carr (GlaxoSmithKline); J.-H. Seol, R. Azzam, K. Sakamoto, R. Verma, R. Feldman, G. Reynard, W. Reynolds, S. Chen, J. Jang, A. Kumagai, P. Mueller, W. Dunphy, B. Hay, P. Sternberg, K. Zinn, B. Wold, M. Budd, J. DeModena, and D. Harrington (Caltech); K. Morimoto and L. Hoopes (Pomona College); G. P. Moore (Freelance U.); and HHMI, NIH, and even INS — it is all SO unfair!
*The transcriber was at the Rockefeller University, New York, NY, 10021
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