Open Access ISSN: 2168-9547
Molecular Biology
Short Communication
Volume 10:1, 2021
Halotag System-Novel Protein Technology
Government College University Lahore, Punjab, Pakistan
*Address for Correspondence: Abdul Razzaq Government College University
Lahore, Punjab, Pakistan, E-mail: praimbaboo786@gmail.com
Copyright: © 2021 Abdul Razzaq, et al. This is an open-access article distributed
under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the
original author and source are credited.
Received 16 March, 2021; Accepted 28 March, 2021; Published 08 April, 2021
Introduction
Generally, HaloTag includes the HaloTag protein and differential functional
groups are present alongwith selected HaloTag ligands. Protein of interest
(POI) gets fused to HaloTag protein easily. The HaloTag ligands bind to the
HaloTag fusions with covalent bonds and are specific in nature.
In this example there is studied the expression of HaloTag protein
and ligand of wild and mutant type dehalogenase on protein expression.
The intermediates were formed and their catalysis was studies by adding
bases which effects the reaction in wild but there was no effect on mutant
type intermediate. A comparison studies shows that the reactions remain the
same [1].
Halotag which is an artificially developed HaloalkaneDehalogenase can
form ester bonds with a chloro-alkane functionalized surface was used with
thiol chemistry to achieve this goal. For the covalent attachment of proteins to
surface, the procedure of using a Halotag is becoming popular. As an example
we can look at the successful use of fusion proteins and terminal Halotag
to label live cells and purify proteins with increased purity and high yield.
Another example is the use of Halotag in single molecule force spectroscopy
to immobilize poly Filamin to beads through DNA spacers and poly 127
polyprotein to mica surfaces [2].
Although covalent anchoring extends the lifetime, has high detachment
forces, increased tethering time and increased range of forces to which a
single molecule can be exposed, due to the little knowledge about Halotag
its potential use in single molecule experiments is limited. The denaturation of
Halotag under certain conditions poses both advantages and disadvantages.
One advantage of Halotag as compared to other covalent attachment
techniques is its mechanical fingerprint caused due to its extension up
to its chloroalkane anchoring point and unfolding. The number of trapped
amino acids within the protein fold and the direction of the pulling force
must also be taken into consideration when looking at the response of
Halotag to the denaturing forces. The interference of Halotag on the
studied process might pose the biggest disadvantage for this process [3].
Investigation into the effects of the refolding and unfolding of two model
proteins and the methods employed to attach proteins using chemistry
and HaloTag-chloroalkane anchoring is reported here [4]. Analytical tools
were developed to verify the specific HaloTag attachment to chloroalkane-
functionalized surfaces. Unfolding mechanisms of Halotag caused by
force-clamp AFM and force extension are discussed here. By uncoupling
its refolding and unfolding from these proteins of interest, the mechanical
properties of Halotag are used to show the usage of HaloTag to investigate
mechanical properties of other proteins. Through measure folding of
Halotag fused polyproteins and Halotag anchoring a guide for successfully
employing covalent attachment of polyproteins is provided.
Protein-protein interaction
Protein-Protein interaction occurs during the cellular signalling while
protein-DNA interaction requires complex techniques. The HaloTag
technology has limited the research in order to save time allowing scientists to
visualize the interaction among intracellular and extracellular transmembrane
proteins by using micro patterning techniques. Halotag technique adaptation
helped them to examine the epidermal growth factor receptor present in living
cells to measure the dissociation contents of several protein complexes.
Halotag has been used for the investigation of interactions between protein-
DNA by using highly effective methods for the analysis of human genes [5].
Protein-DNA interactions
Designing of well-defined structures is favored by the incomparable
specificity of various sequences of DNA oligonucleotides and base pairing.
Oligonucleotides are practical for use in multiple applications due to their
mechanical stability and ready availability. Effective drug delivery is enabled by
the therapeutic application of conjugates composed of proteins or peptides and
single stranded DNA. DNA-protein and protein-protein interactions are also
an application of this. The fabrication of protein arrays also use DNA-protein
conjugates which provide universal and reversal binding surface, enhanced
binding capacity and increased reversibility.
Bio analytical immune assays also use DNA-protein conjugates to help in
signal generation. The ultrasensitive immune assays have been enabled by
immuno-RCA (rolling circle amplification) and immuno-PCR (polymerase
chain reaction) by measuring the amplification product formed by conjugated
oligonucleotide. Analyte recognition uses two separate oligonucleotide-
binder conjugates which are used in proximity ligation assays. Template
is formed by the ligation of two sequences for nucleic acid amplification
after the analyte-bound antibodies bring the conjugated oligonucleotide
sequences. Using direct luminescence-based detection reporter-labeled
oligonucleotide-binder conjugates have been used. The production of the
DNA-protein conjugates and their high performance in assays is enabled
by conjugation chemistry. A widely used and well established method is
the covalent conjugation using cross-linkers to primary amine or sulfhydral
groups of the protein. Because of the availability of several sites in a
protein the conjugation is uncontrollable. The amount of oligonucleotide
per antibody may vary from batch to batch and the random oligonucleotide
conjugation to a protein may interfere with analyte recognition. The
modification of recombinant binders to enable site-specific coupling and
stoichiometric conjugation overcomes this problem.
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Shaohua Liu, Xiaodong Zhuang, and Xinliang Feng. "Interface engineering
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Abdul Razzaq*, Muhammad Zeeshan Khalil, Umar Farooq, and Nashmia Kamran