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NEWS
June 2024 ESRFnews
ESRF stages cryo-electron tomography
living environments.
Two teams led by Guy Schoehn
and Cecile Morlot at the Institut de
Biologie Structurale in France have
now trialled cryo-ET on bacterial
spores at the ESRF’s CM01 facility
and at the Central European Institute
of Technology in Brno, in the Czech
Republic. Bacterial spores are dormant
cells that can resist multiple stresses,
from antibiotics and disinfectants to
irradiation and high temperatures.
Their resistance is helpful when the
spores have a human benefit for
example in probiotics but it poses a
major problem if they are harmful as
there are limited ways to eradicate them
The researchers used cryoET to
study the structure of the spores
chromosome as well as its coat
the extracellular multiprotein
structure responsible for many of the
spores resistance properties They
found that during sporulation the
chromosome organises into a torus
shaped bundle of fibrils which is
likely a transition stage between
the initial compact structure of the
spore DNA and its final crystalline
structure. Meanwhile, the spore coat
assembles within distinct, stacked
layers formed by scaffolding proteins
(Nat. Commun. 15 1376). “Our work
lays the foundations for the dissection
of molecular mechanisms involved in
the development and the resistance of
the bacterial spore,” says Morlot.
Gregory Effantin, the CM01
scientist who collected the ESRF
data believes the technique has great
potential at the facility CryoET
provides both structural information
about individual protein complexes
and their spatial organisation within
the cell he explains It has the
potential to greatly advance structural
biology and cell biology in particular
by bridging the gap between light
microscopy and highresolution
approaches such as singleparticle
cryoEM Xray crystallography and
nuclear magnetic resonance
ESRF users and their colleagues have
conducted one of the first studies of
bacterial spores using cryo-electron
tomography (cryo-ET). The results
are helping researchers to understand
how bacterial spores become resistant
to hostile conditions, and show the
nascent technique’s potential for “in
cell” structural biology.
In the last decade, cryo-electron
microscopy (cryo-EM) has
transformed structural biology due
to its ability to obtain 3D structural
information without needing a
sample to be crystallised which is
often very difficult The next step
has been cryoET in which a larger
sample of biological tissue is plunge
frozen before being thinned and
imaged with an electron microscope
with nanometric resolution With
cryoET structural biologists have the
opportunity to move away from in vitro
studies and towards collecting data
from within the cell where proteins are
under the varied influences of their real
“Cryo-ET
provides both
structural
information
about
individual
protein
complexes and
their spatial
organisation
within the cell
E S R F/ S T E F C A N D É