Deep-sea osmolyte finds applications in molecular machines

Date:
April 7, 2022
Source:
Hokkaido University
Summary:
The molecule trimethylamine N-oxide (TMAO) can be used to reversibly
modulate the rigidity of microtubules, a key component of molecular
machines and molecular robots.



FULL STORY ==========================================================================
The molecule trimethylamine N-oxide (TMAO) can be used to reversibly
modulate the rigidity of microtubules, a key component of molecular
machines and molecular robots.


========================================================================== Kinesin and microtubules (MTs) are major components of cytoskeleton
in cells of living organisms. Kinesin and microtubules together play
crucial roles in a wide range of cellular functions, most significantly intracellular transport.

Recent developments in bioengineering and biotechnology allows for
using these natural molecules as components of molecular machines and
molecular robots. In vitro gliding assay has been the best platform to
evaluate the potential of these biomolecules for molecular machines.

A team of scientists led by Assistant Professor Arif Md. Rashedul Kabir
of Hokkaido University has reported a simple and straightforward method
to reversibly and dynamically control the rigidity of kinesin propelled
MTs. Their findings have been published in ACS Omega,a journal published
by the American Chemical Society (ACS).

In an in vitro gliding assay, kinesin molecules are attached to a base material, and propel MTs as the molecular shuttles. The rigidity of
the motile MTs is a crucial metric that determines the success of their applications as the component of molecular machines. One of the major
hurdles in regulating the rigidity of MTs is that previous methods
affected the rigidity of MTs permanently and were irreversible. The
development of a method to control the rigidity of MTs in a reversible
manner would allow for dynamic adjustment of MT property and functions,
and would be a massive development in molecular machines, molecular
robotics, and related fields.

Kabir and his colleagues employed trimethylamine N-oxide (TMAO), a
molecule that acts as an osmolyte in many deep-sea organisms, to study its effects on MTs in an in vitro gliding assay. TMAO is known to stabilize proteins under stressful or denaturing conditions of heat, pressure,
and chemicals. The team demonstrated that TMAO affects the rigidity of
MTs without depending on the need for any modifications to MT structures.

At relatively low TMAO concentrations (0 mM to 200 mM), MTs remained
straight and rigid and the motion of the MTs in the gliding assay was unaffected. As the TMAO concentration was increased further, the MTs
showed bending or buckling, and their velocity decreased. The team
quantified this effect of TMAO on the conformation of the MT, showing
that the persistence length, a measure of rigidity, of MTs was 285 +/-
47 ?m in the absence of TMAO and that decreased to 37 +/- 4 ?m in the
presence of 1500 mM TMAO.

The team further demonstrated that the process was completely reversible,
with MTs regaining their original persistence length and velocity when
the TMAO was eliminated. These results confirmed that TMAO can be used to reversibly modulate the mechanical property and dynamic functions of MTs.

Finally, the team has investigated the mechanism by which TMAO alteres
the rigidity of MTs. Based on their investigations, Dr. Arif Md. Rashedul
Kabir and his team members concluded that TMAO mediates disruption of
the uniformity in force applied by the kinesins along MTs in the gliding
assay; the non-uniform force generated by the kinesins appeared to be responsible for the change in rigidity or persistence length of the
kinesin propelled MTs.

"This study has demonstrated a facile method for regulating the MT
rigidity reversibly in an in vitro gliding assay without depending on
any modifications to the MT structures," Kabir said. Future works will
focus on elucidating the exact mechanism by which TMAO acts, as well
as, on utilizing TMAO for controlling the properties and functions of
MTs and kinesins, which in turn will be beneficial for the molecular
machines and molecular robotics.


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


========================================================================== Journal Reference:
1. Arif Md. Rashedul Kabir, Tasrina Munmun, Tomohiko Hayashi, Satoshi
Yasuda, Atsushi P. Kimura, Masahiro Kinoshita, Takeshi
Murata, Kazuki Sada, Akira Kakugo. Controlling the Rigidity of
Kinesin-Propelled Microtubules in an In Vitro Gliding Assay Using
the Deep-Sea Osmolyte Trimethylamine N-Oxide. ACS Omega, 2022; 7
(4): 3796 DOI: 10.1021/ acsomega.1c06699 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220407101033.htm

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