New spheres of knowledge on the origin of life

Date:
January 12, 2022
Source:
University of Tsukuba
Summary:
Researchers experimentally evolved rod-shaped E. coli in conditions
that mimic the primordial environment, by providing oleic-acid
vesicles as a nutrient source rather than glucose. As the cells
adapted to the new conditions and increased their growth rate, they
became smaller and spherical. Each of the experimental lineages
adapted in diverse ways.

This study supports theories that the origin of life on Earth was
spherical cells.



FULL STORY ==========================================================================
The shape of a cell affects its physical and chemical
properties. Different cell types have developed different shapes to
enable effective functioning. But what shape were the very first cells,
as life began to evolve?

========================================================================== Primitive cells are thought to have been spherical, but experimental
evidence supporting this belief remains elusive. Now, however, researchers
from the University of Tsukuba, in collaboration with East China Normal University, have shown that E. coli bacteria grown in a primordial-like environment become spherical.

The primordial environment on Earth is thought to have consisted of
vesicles, or compartments, of fatty acids. Oleic acid is the most
common fatty acid in nature and can be metabolized by E. coli. The
team therefore mimicked primordial conditions by growing six different
lineages of cells in an environment where the only available nutrient
was oleic-acid vesicles (OAVs), rather than the more usual glucose sugar.

E. coli's usual rod shape allows rapid growth and nutrient
uptake. However, their shape can change in response to their environment, turning into a filament when starved of nutrients. "Our team grew
these bacteria in an OAV environment and found that as the cells better
adapted to the new conditions, they grew more quickly, became spherical,
and decreased in both size and area- to-volume ratio compared with
the original parent cells (Ori cells)," says senior author Professor
Bei-Wen Ying. "Even when we relocated these evolved cells (Evo cells)
to a glucose environment, they maintained their new spherical shape."
The six different lineages of Evo cells all evolved to adapt to the OAV conditions without common mutations. Notably, two distinct strategies
were observed: some cells developed mutations that directly targeted
the cell wall so that the cell structure became spherical, while others accumulated mutations in other biological processes.

Three of the six lineages developed various mutations in the common
crp gene.

The protein product of crp acts as a regulator of transcription, the
process by which the genetic information in the DNA is turned into a
molecule known as RNA. "This implies that transcriptional regulation by
crp may be crucial for E.

colito use carbon sources effectively," explains Professor Bei-Wen Ying.

This work is the first to show typically rod-shaped cells shifting to
a spherical shape in a primordial-like environment, supporting the
theory that when life began to evolve, the earliest primitive cells
were spherical.

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


========================================================================== Journal Reference:
1. Hui Lu, Honoka Aida, Masaomi Kurokawa, Feng Chen, Yang Xia, Jian
Xu, Kai
Li, Bei-Wen Ying, Tetsuya Yomo. Primordial mimicry induces
morphological change in Escherichia coli. Communications Biology,
2022; 5 (1) DOI: 10.1038/s42003-021-02954-w ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220112121548.htm
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