There's a reason bacteria stay in shape
Theorists show how random processes cancel out to ensure microbial health


Date:
October 6, 2020
Source:
Rice University
Summary:
A simple theoretical model seeks to explain why bacteria remain
roughly the same size and shape. The work by chemists could offer
new insight into diseases, including cancer.



FULL STORY ==========================================================================
Fat bacteria? Skinny bacteria? From our perspective on high, they all
seem to be about the same size. In fact, they are.


========================================================================== Precisely why has been an open question, according to Rice University
chemist Anatoly Kolomeisky, who now has a theory.

A primal mechanism in bacteria that keeps them in their personal
Goldilocks zones -- that is, just right -- appears to depend on two
random means of regulation, growth and division, that cancel each other
out. The same mechanism may give researchers a new perspective on disease, including cancer.

The "minimal model" by Kolomeisky, Rice postdoctoral researcher and lead
author Hamid Teimouri and Rupsha Mukherjee, a former research assistant
at Rice now at the Indian Institute of Technology Gandhinagar, appears
in the American Chemical Society's Journal of Physical Chemistry Letters.

"Everywhere we see bacteria, they more or less have the same sizes
and shapes," Kolomeisky said. "It's the same for the cells in our
tissues. This is a signature of homeostasis, where a system tries to have physiological parameters that are almost the same, like body temperature
or our blood pressure or the sugar level in our blood.

"Nature likes to have these parameters in a very narrow range so that
living systems can work the most efficiently," he said. "Deviations from
these parameters are a signature of disease." Bacteria are models of homeostasis, sticking to a narrow distribution of sizes and shape. "But
the explanations we have so far are not good," Kolomeisky said.

"As we know, science does not like magic. But something like magic - - thresholds -- is proposed to explain it."


==========================================================================
For bacteria, he said, there is no threshold. "Essentially, there's
no need for one," he said. "There are a lot of underlying biochemical processes, but they can be roughly divided into two stochastic chemical processes: growth and division. Both are random, so our problem was to
explain why these random phenomenon lead to a very deterministic outcome."
The Rice lab specializes in theoretical modeling that explains biological phenomena including genome editing, antibiotic resistance and cancer proliferation. Teimouri said the highly efficient chemical coupling
between growth and division in bacteria was far easier to model.

"We assumed that, at typical proliferation conditions, the number of
division and growth protein precursors are always proportional to the
cell size," he said. T he model predicts when bacteria will divide,
allowing them to optimize their function. The researchers said it agrees
nicely with experimental observations and noted manipulating the formula
to knock bacteria out of homeostasis proved their point. Increasing the theoretical length of post-division bacteria, they said, simply leads
to faster rates of division, keeping their sizes in check.

"For short lengths, growth dominates, again keeping the bacteria to the
right size," Kolomeisky said.

The same theory doesn't necessarily apply to larger organisms,
he said. "We know that in humans, there are many other biochemical
pathways that might regulate homeostasis, so the problem is more
complex." However, the work may give researchers new perspective on
the proliferation of diseased cells and the mechanism that forces,
for instance, cancer cells to take on different shapes and sizes.

"One of the ways to determine cancer is to see a deviation from the norm," Kolomeisky said. "Is there a mutation that leads to faster growth or
faster division of cells? This mechanism that helps maintain the sizes and shapes of bacteria may help us understand what's happening there as well."

========================================================================== Story Source: Materials provided by Rice_University. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Hamid Teimouri, Rupsha Mukherjee, Anatoly B. Kolomeisky. Stochastic
Mechanisms of Cell-Size Regulation in Bacteria. The
Journal of Physical Chemistry Letters, 2020; 8777 DOI:
10.1021/acs.jpclett.0c02627 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201006132122.htm

--- up 6 weeks, 1 day, 6 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)