Journal of Petroleum & Environmental Biotechnology

Studies of Various Components of Orange Carotenoid Protein (OCP) and their Evolution

Sijil James^* Department of Botany, CMS College, Kottayam, Kerala, India
^*Correspondence: Sijil James, Department of Botany, CMS College, Kottayam, Kerala, India, Email:

Received: 03-Jan-2023, Manuscript No. JPEB-23-19545; Editor assigned: 05-Jan-2023, Pre QC No. JPEB-23-19545 (PQ); Reviewed: 20-Jan-2023, QC No. JPEB-23-19545; Revised: 27-Jan-2023, Manuscript No. JPEB-23-19545 (R); Published: 03-Feb-2023, DOI: 10.35248/2157-7463.23.14.501

INTRODUCTION

Cyanobacteria have various pigments that have potential applications in the field of industry, environment as well as biotechnology. The photoprotective mechanism involving the two forms of Orange Carotenoid Protein (OCP) is a complex phenomenon that requires the study of each of its forms and related components. The evolution of OCP led to the discovery of its components and how its modifications can change the productivity of OCP.

Preface of the Book

The confidence laid on me by the entire Ph.D. Phycology crew members of CMS College, Kottayam (Kerala, India) including Syama Prabha, Aravind K Vijay, and Zaid along with the support of my guide Prof. Dr. Basil George led me to focus on Orange Carotenoid Protein (OCP). This was a part of my review paper prepared for the project thesis which was repeatedly modified by the research scholars. This is a team work where the topic, modifications, and refinement were done with a written work part laid on me. This is a new year gift I never planned to give in the year 2023 but I aimed to once I reach Australia. I need to thank God almighty, my parents, my sister, and all the well-wishers who made me, who I am now.

Echinenone Studies

Along with the studies regarding the photoactivation and recovery of Orange Carotenoid Protein (OCP), it was analysed that there is a rupture of Echinenone β₁ ring-Y201/W288 and present hydrogen bonding interaction to release the carotenoid into N-terminal domain and hence N terminal extension must dissociate from theβ-sheet face for the domain separation [1]. A study based on the activity of echinenone associated with the inactive form of OCP revealed that echinenone exists in a highly distorted cis-trans configuration. When the deformation including the backbone isomerization, end ring rotation, and normal distortions was studied, it was observed that inversion symmetry is broken down by isomerization and when the examination of the S₁ and S₂ Transition Dipole Moment (TDM) for Molecular Dynamics (MD) trajectories were made, negligible variance in the average symmetry with S₁ was also concluded. The mixing and burrowing of TDM by S₁ induced by modulation of effective conjugation length will affect the S₁-S₂ energy gap. From the dates collected, it was inferred that two groups of vibrations used to have a strong effect on the S₁-S₂ energy gap. In the case of distortion studies, for distortion larger than a124=0.1 S₁ and S₂ cross, the double homolumo state S is denoted. The effects of modes in S₁ were studied with a focus on the steep slope obtained about a214=0 where calculations were stable [1].

Bending of echinenone

Variances in modes by the mean contribution demonstrated that there is overall bending of the molecule of echinenone. When OCP is considered it was justified that the production of twisting without any net change to bond length alterations can be achieved by the combination of several high-frequency modes. Without relating to inversion symmetry it was in countenance that larger Biologics License Application (BLA) lowers the S₁-S₂ state mixing. By considering the absorption spectrum denoting the spectral densities of S₁ and S₂ from Molecular Dynamics (MD) in black and ansatz density in red, corresponding peaks at 1100/cm and 1700/ cm indicating the optically coupled C-C and C=C vibrations were obtained. The term optical forbidden for the S₁ state was signified by the conclusion drawn from the experiment conducted which revealed that S₁ was more displaced from the ground state than S₂ by comparing the spectral density [2].

Changes during photoactivation

The changes happening to echinenone during the activation of Orange Carotenoid Protein (OCP) which act as a high-powered molecular switch was studied along with the data analysed that the resolution of 2.1A and 1.5A was obtained in the X-ray structure of OCP from Arthrospira maxima and Synechocystis PCC 6803 [2]. Resonance Raman analysis due to its being a vibrational technique, give detailed information about the molecules that scatter photons. The assumptions and data collected infer that some groups like technion which is a carotenoid containing a conjugated carbonyl group may give rise to additional electronic states like Intramolecular Charge Transfer (ICT). It is important to study in detail the various interactions carried out in presence of such groups. From the Resonance Raman studies it was drawn that during the transition from the inactive state to the active state of OCP, there is an increase in the echinenone conjugation length. The observations were made on the concept that four spectral regions are exhibited by carotenoid, V₁-V₄ after the analysis, it was confirmed that the OCP transition from orange to red induces three main changes in the Resonance Raman spectrum.

They are;

Downshift of the frequency of the V₁ band.

A reduction in the intensity of the V₄ band.

Small changes in the structure of V₂ and V₃ bands..

The final studies confirmed that the hypothesis can be assured by the observation that the red-absorbing echinenone corresponds to molecules with longer conjugated chains and thus display V₁ Raman bands with lower frequencies. Also, the presence of two configurations of echinenone exists in the inactive form of OCP and only one in red form. These observations concluded and confirmed the hypothesis of change in S₁ energy during hydoxyechinenone and OCP association [3].

Effect of echinenone and zeaxanthin in Non- Photochemical Quenching (NPQ) mechanism

The study to recognize the influence of zeaxanthin and echinenone was carried out by constructing mutants lacking both. The process was carried over by the amplification of the genome region containing the city gene which codes for beta carotene monoketolase using Polymerase Chain Reaction (PCR) and then, it was cloned. The construction of a plasmid in the cut gene was deleted and replaced by Sp/Sm resistance cassette. The resultant plasmid was used to transform the wild type, a His-tagged OCP strain, and another expressing His-tagged OCP strain. These constructions stimulated further experiments to undertake mutant selection cells using antibiotics. From the analysis, it was concluded that hydroxyechinenone can be replaced by echinenone signifying its role in photoprotection while the zeaxanthin is irreplaceable. Zeaxanthin was observed to have two hydroxyl groups, one in each ring [4].

Analysis of Paralogs and Homologs of OCP and their Components

Paralogs of OCP and their function

The discovery of Cyanobacterial subsections having hypothetical proteins with sequences homologous to OCP-NTD (N-Terminal Domain) and which can fix molecular nitrogen, containing ntd-like genes is a significant breakthrough to study its effects on the Non- Photochemical Quuenching (NPQ) mechanism. Even though many Cyanobacterial strains have genes encoding NTD-OCP homologs and (C-Terminal Domain) CTD-OCP homologs, the functional role of these homologs is entirely different from the specific OCP encoding genes. Thus, the rate and expression of NPQ will also vary, during the studies tackled with anabaena sp.PCC 7120, it was detected that the genome of anabaena has four genes encoding NTD-OCP-like proteins, viz, all3221, all4783, all4941, and all1123. Many similarities were observed between the isolated paralogs, viz, and-like genes and the NTD region of the OCP gene. When SDS gel electrophoresis was carried out, similarity in the apparent molecular mass led to the experiments related to the size.

The interaction and presence of carotenoid in the isolated anabaena NTD-OCP and 4 NTD paralogs were confirmed by the liquidchromatography and mass spectrometry which had been indicated by its red-violet colour. The action of fluorescence quenching by anabaena NTD-OCP was successful using PBS isolated from Synechocystis or anabaena. The presence of NTD paralogs in anabaena cells was confirmed by the western blot analysis. The recognition of proteins of 15 kD by the antibody against anabaena all1123 confirmed that at least one of the NTD paralogs that are recognized by this antibody is present in the vegetative phase and as in heterocysts.

OCP homologs

After the study of OCP homologs in N. flagelliform, it was concluded that there are 7 genes encoding the homologs where they are located in the chromosome. These 7 genes were grouped into 3, after a mere comparison with Synechocystis sp PCC 6803.

• Two full-length OCP proteins with carotenoid-N and Nuclear Transport Factor 2 (NTF2) domains were evolutionarily placed within the OCPx family.

• 4 OCP homologs with a singly N-terminal carotenoid N-domain

• One OCP homolog contains only the C-terminal NTF2 domain which was designated.

Genomic studies helped to analyze and characterize 3 paralog families of OCP, viz, OCP₁, OCP₂, and XP. Most OCPs belong to the OCP₁ family which includes Synechocystis PCC 6803, Arthrospira maxima, and anabaena PCC 7120. Only one OCP₂-Tolypothrix PCC 7601 and one OCPx–Scytonema Hofmann PCC 7110 had been characterized. The Recombinant Fucolectin-Related Protein (FRP) gene is absent in strains containing only OCPx and OCP₂. In these strains, OCPx and OCP₂ can detach from Phycobilisome (PBS) and allow recovery even though the FRP is completely absent. The Fluorescence Recovery Protein (FRP) dimer usually interacts with high affinity with the C-Terminal Domain (CTD) of OCP₁r. It was also observed that both OCP₁ and OCP₂-based heterodimers are photoactive and upon illumination, both become photoactive to OCP. But in the red form, the ٨max of heterodimers is red-shifted.

Conclusion

It is the discovery of various components of Orange Carotenoid Protein (OCP) that led to the engineering of this pigment. A study of each component and its variants in different cyanobacterial members is necessary to make it applicable for its utility in different fields.

Acknowledgment

I express my sincere gratitude to God Almighty who paved a path for me to give a gift to the ones who laid milestones in my life. I thank my parents who supported me although the struggles I faced made me bold. My sister, Simil James was the greatest inspiration as she helped me to get a better idea about how a research methodology works well. This is entirely my gift for CMS College, Kottayam, Kerala, India (Phycology Ph.D. scholars and Prof. Dr. Basil George). I reached here at Melbourne safely with my aunt Binny and family with George uncle and Lena who supported me here for the completion of this work.

Conflict of the Interest

I classified my field of interest into the talented field and blessed field when I reached Australia. I think this work helped me to achieve both simultaneously.

This day 07-01-2023 is very special and this time 11:43 pm here is still more special because it reminds me of that special person who taught me the sweetness of failure, the silence of success, and finally the significance of being real and honest. I am thankful to you for supporting me for the past six years by being a friend, guardian, and eventually, the person on whom I see God’s reflection and it seems you are my cleat-cut copy.

Now I realized how surprisingly my two fields of interests combined to give a new gift to my well-wishers. I thank all those from Kairali Balavihar Montessori and Play School (Kaloor), Sree Narayana Public School (Poothotta), Bharata Mata College (Thrikkakkara), and C.M.S College, Kottayam.

Here, in Australia, many students, research scholars, friends, families, and even strangers taught me many lessons regarding how to distinguish real and fake. Australia turned out to be a new land full of opportunities. Here, I desire to achieve something special.

Being a youngster, it is my pleasure to submit a review in such a wonderful journal – the JOURNAL OF PETROLEUM AND ENVIRONMENTAL BIOTECHNOLOGY under the guidance of Arthur J Ragauskas.

References

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