News

To Schmoo or not to Schmoo- That is the question.- Biotech yeast project explores mechanics of schmoo

It’s not much as sex shows go, but researchers at
the Molecular Sciences Institute must find it
captivating.

Tom Abate San Francisco Chronicle

In their offices overlooking the downtown Berkeley
BART station, they plan to spend the next five years
studying in mathematical detail the mating rituals of
yeast.

"Yeast comes in two sexes," said Roger Brent,
president of the nonprofit think-tank. They don’t lead
a very interesting life, he says, but sex is one of the
benefits.

Using a newly announced $15.5 million grant from
the Human Genome Project, Brent will enlist 40
academic scientists, including UC Berkeley
chemistry Professor Julie Leary, in an effort that
exemplifies the fundamental premise of
biotechnology.

When biotech scientists study people, mice, fruit
flies or yeast, they view their subjects as machines.
Complex machines no doubt, but machines
nevertheless, in which DNA plays the role of the
master controller and RNA serves as its
manufacturing arm, churning out the proteins that are
the gears, motors, switches and transistors of every
living thing.

The Human Genome Project was hailed as an
important advance in understanding the workings of
the body. But it is only a baby step toward achieving
the sort of mathematical formulas that engineers use
to design and troubleshoot ordinary machines. The
automaker who wants to build a bumper capable of
surviving a fender-bender knows the impact
characteristics of a given thickness of steel, for
instance.

But organisms are so complex, their parts so
minuscule, that scientists are only beginning to
grasp what happens when the proteins inside a cell
interact to accomplish a task such as firing a nerve
cell or flexing a muscle.

And though they know roughly how these molecular
mechanisms transpire, so far scientists can’t
compute the forces that enable proteins to do the
cell’s work — or stop them from carrying out a
necessary task. In short, they want to understand
exactly what molecular conditions make us healthy
or sick.

But even for the scientists who mapped the genome,
discovering the mathematics of life is such a
daunting task that Brent’s groundbreaking project
targets one of the simplest, most widely observed
phenomena in biology — the protein interactions
through which yeast cells decide whether or not to
mate.

Though they may seem like indistinguishable blobs
under the microscope, the two mating types of yeast,
which scientists call A and Alpha, literally ooze
sexuality at the molecular level. To be more precise,
Brent said, yeast cells emit and receive pheromones,
the name given to the proteins that transmit sexual
signals.

As Brent explained it, yeast cells are choosy about
mating. When one yeast cell captures an interesting
pheromone, the recipient goes through a decision-
making process. If food is plentiful, the yeast may
forgo sex and keep chowing down.

But when the mood is right, the receiving yeast cell
will signal back to accept the offer. The mating yeast
will then begin making "shmoo tips" — a term
playfully derived from the character in the "Li’l Abner"
cartoon strip. These schmoo tips are protuberances
that grow toward one another until the two yeast cells
have fused into one.

"There are about a dozen proteins and a couple of
hundred known interactions in this process," Brent
said.

In scientific terms, this type of process is called a
g-protein coupled pathway. Yeast cells have only one
g-protein coupled pathway, the one they use to
decide whether or not to shmoo.

But evolution has taken this basic set of protein
interactions and greatly expanded its use in higher
organisms, such as Chronicle readers.

When we see or smell, for instance, the molecular
underpinnings are g- protein processes. When we get
frightened and adrenaline rushes through our blood,
the molecular upshot is a flood of g-protein signals
that prepare the muscles and lungs to fight or flee.
Many cancers involve g-protein malfunctions.

"You and I have 2,000 different g-protein coupled
receptors," Brent said. "About half of the dollar
volume of all the drugs developed today involve g-
protein coupled receptors."

All of which goes a long way toward explaining why
Francis Collins, director of the federally funded
National Human Genome Research Institute,
awarded Brent $15.5 million — surely not to help
yeast cells find their G- spot.

"If we can figure out this (process) in yeast we can
apply this knowledge to g-protein receptors in other
cells," said Brent.

As recipients of a federal grant, Brent’s team will put
any techniques and formula they discover into the
public domain for other scientists to use and improve
upon.

Ultimately, biotech scientists won’t stop with
g-protein pathways. They want to chart every detail of
life’s machinery in precise mathematical terms.

Or, as Brent said: "Eventually the biologists will have
to get as smart as the biology."

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2002/08/19/BU141187.DTL

Posted in:

Sorry, we couldn't find any posts. Please try a different search.

Leave a Comment

You must be logged in to post a comment.