The DnaK-associated protein All4144 from the Cyanobacterium Anabaena sp. PCC7120, a thermos-sensor GrpE, act as a
nucleotide exchange factor and binds to DNA
Sonam Sriwastaw and L.C. Rai*
Molecular Biology Section, Department of Botany, Institute of Science, Banaras Hindu University, Varanasi -221005
*Corresponding Email: lcrbhu15@gmail.com
THE INTERNATIONAL CONFERENCE ON BEYOND FOSSIL FUELS (B:FAT 2020)
Introduction
Fig 4
Objective
Fig 5
Cyanobacteria heat shock proteins(Hsps) respond to wide range of environmental stress such as
heat, cold, drought and salt
Molecular chaperones mediate conformational changes such as misfolding, refolding,
aggregation, and degradation, allowing cyanobacteria to maintain protein homeostasis and adapt
to stress.
Among all stress-responsive molecular chaperone proteins, the DnaK/Hsp70 system is one of
the most common.
However, since DnaK has low intrinsic ATPase activity and slow ADP dissociation kinetics,
DnaK's ATPase activity and ADP recycling depend on co-chaperons GrpE and DnaJ.
GrpE, DnaK nucleotide exchange factor (NEF) is evolutionarily conserved and acts as a
thermos-sensor .
All4144 belong to unique GrpE family, which act as a nucleotide exchange factor for DnaK and
also bind to DNA.
Results & Discussion
Fig 1
Fig 2
OER performance of the electrocatalyst is done using LSV measurement, performed at 2 mV sec1.
(c)
Overpotential at current density of 10 mA cm-2 for MoSe2 is found to be ~ 407 mV at scan rate of 2
mV sec-1.
Tafel slope of MoSe2 of 84 mV/decade have been achieved as scan rate of 2 mV sec-1.
Nyquist plot fitted with a Rs(Q1R1)(Q2RCT) equivalent circuit model, shows low charge transfer
resistance.
Fig 3
The iR corrected LSV curve show overpotential of 391 mV at 10 mA cm-2 and corresponding
Tafel slope 79 mV decade-1.
Chronoamperometry shows high stability up to 12 h at constant potential.
Conclusions
We have hydrothermally synthesized few layer MoSe2 nanosheets and characterized them.
 We show overpotential (η10~ 407 mV) and Tafel slope (84 mV dec-1) for MoSe2 nanosheets at scan
rate of 2 mV sec-1.
 Synthesized MoSe2 nanosheets is stable up to 12 h showing good and stable catalytic behaviour.
The good extracatalytic activity is observed due to the presence of high number of active sites
because of Se vacancies and large number of edges.
References
1. J. Ding, P. Wang, S. Ji, H. Wang, V. Linkov and R. Wang, Electrochimica Acta, 2019, 296, 653–
661.
2. Y. Yan, S. Liang, X. Wang, M. Zhang, S. M. Hao, X. Cui, Z. Li and Z. Lin, Proc Natl Acad Sci U S
A 2021, 118 (40).
Acknowledgement
 Authors acknowledge the support of IIT (BHU) and its Central Instrument Facility, SERB, India
(Grant No. CRG/2020/002186) and DST, India (Grant No. IFA14-MS25).
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environmental stress such as heat, cold, drought and salt
heat shock proteins (Hsps) mediate conformational changes such as
misfolding, refolding, aggregation, and degradation, allowing
cyanobacteria to maintain protein homeostasis and adapt to stress.
Among all stress-responsive heat shock proteins, the DnaK/Hsp70
system is one of the most common.
However, since DnaK has low intrinsic ATPase activity and slow ADP
dissociation kinetics, DnaK's ATPase activity and ADP recycling
depend on co-chaperons GrpE and DnaJ.
GrpE, DnaK nucleotide exchange factor (NEF) is evolutionarily
conserved and acts as a thermos-sensor.
All4144 belongs to the unique GrpE family, which act as a nucleotide
exchange factor for DnaK and binds to DNA.
the unique GrpE family, which act as a nucleotide exchange factor for DnaK and
Investigation of all4144 role in
heat stress management.
Comparative study of WT
All4144 and generated a
truncated variant of All4144.
Compared to the pET28a-all4144, the growth of the former was
noticeably better (68-214). The importance of recombinant plasmids for
boosting heat tolerance is illustrated by these findings.
ROS results showed that BL21/pET-28a-all4144 and BL21/pET-28aall4144(68-214) cells reduced the H2DCFDA intensity by 2.6-fold and
1.6-fold compared to BL21/pET-28a cells (control)
Circular dichroism (CD) and differential scanning calorimetry (DSC)
analyses of protein folding and thermal stability revealed that WT
All4144 is more stable than truncated variants All4144 (68-214)
Overall, the results of CD and DSC analyses provide valuable insights into the structural and
thermodynamic properties of proteins and can help to identify regions of the protein that are
critical for its stability and function.
Result and Discussion
Refolding assay
ATPase assay buffer