Maternal Periodontitis Prevalence and its Relationship with Preterm and Low-Birth Weight Infants: A Hospital-Based Research.

Introduction: Overall wellness depends on oral health. Epidemiological, clinical, and laboratory studies have linked periodontitis to some systemic diseases. Pregnancy labor, contractions, and delivery are controlled by prostaglandin (PGE 2) levels rise during pregnancy, and labor begins when a critical threshold is reached. These associations support the underlying cause of maternal periodontal disease. Materials and Methods: In the study, 3,885 pregnant women aged 18-40 had singleton babies. All mother participants were clinically evaluated by the primary investigator. The periodontal disease is defined using a few parameters. Based on that the prevalence rate will be evaluated. Result: The prevalence of preterm babies' mothers affected with periodontitis was 0.5% and low-birth weight babies' mothers affected with periodontitis was 1.6%. So, there was a significant result is there. Conclusion: Periodontal health and preterm LBW newborns are highly associated with periodontitis in research. It may modify preterm birth and LBW risk factors. Thus, dentists detect and treat this sickness early, preventing pregnancy difficulties in sensitive mothers.

Photoisomerization of phytochrome chromophore models: an XMS-CASPT2 study.

Phytochromes are a superfamily of photoreceptors that harbor linear tetrapyrroles as chromophores. Upon light illumination, the linear tetrapyrrole chromophore undergoes a double bond isomerization which starts a photocycle. In this work, we studied the photoisomerization of chromophore models designed based on the C- and D-rings of the phycocyanobilin (PCB) chromophore. In total, five different models with varying substitutions were investigated. Firstly, the vertical excitation energies were benchmarked using different computational methods to establish the relative order of the excited states. Based on these calculations, we computed the photoisomerization profiles using the extended multi-state (XMS) version of the CASPT2 method. The profiles were obtained for both the clockwise and counterclockwise rotations of the C15C16 bond in the Z and E isomers using a linear interpolation of internal coordinates between the Franck-Condon and MECI geometries. In the minimal chromophore model that lacks the substitutions at the pyrrole rings, the isomerization involves both C14-C15 and C15C16 bonds of the methine bridge between the C- and D-rings, resembling the hula-twist motion. The MECIs are characterized by a partial charge transfer between the two pyrrole rings pointing towards a twisted intramolecular charge transfer. Systematic introduction of substituents leads to an increase in the steric repulsion between the two pyrrole rings causing a pretwist of the dihedral around the C15C16 bond, which creates a preference for the counterclockwise isomerization. An introduction of the carbonyl group at the D-ring increases the extent of charge transfer which changes the isomerization mechanism from hula-twist to one-bond flip.

Correction: Histidine protonation controls structural heterogeneity in the cyanobacteriochrome AnPixJg2.

Correction for 'Histidine protonation controls structural heterogeneity in the cyanobacteriochrome AnPixJg2' by Aditya G. Rao et al., Phys. Chem. Chem. Phys., 2021, DOI: 10.1039/d0cp05314g.

Histidine protonation controls structural heterogeneity in the cyanobacteriochrome AnPixJg2.

Cyanobacteriochromes are compact and spectrally diverse photoreceptor proteins that bind a linear tetrapyrrole as a chromophore. They show photochromicity by having two stable states that can be interconverted by the photoisomerization of the chromophore. These photochemical properties make them an attractive target for biotechnological applications. However, their application is impeded by structural heterogeneity that reduces the yield of the photoconversion. The heterogeneity can originate either from the chromophore structure or the protein environment. Here, we study the origin of the heterogeneity in AnPixJg2, a representative member of the red/green cyanobacteriochrome family, that has a red absorbing parental state and a green absorbing photoproduct state. Using molecular dynamics simulations and umbrella sampling we have identified the protonation state of a conserved histidine residue as a trigger for structural heterogeneity. When the histidine is in a neutral form, the chromophore structure is homogenous, while in a positively charged form, the chromophore is heterogeneous with two different conformations. We have identified a correlation between the protonation of the histidine and the structural heterogeneity of the chromophore by detailed characterization of the interactions in the protein binding site. Our findings reconcile seemingly contradicting spectroscopic studies that attribute the heterogeneity to different sources. Furthermore, we predict that circular dichroism can be used as a diagnostic tool to distinguish different substates.

Frontiers in Multiscale Modeling of Photoreceptor Proteins.

This perspective article highlights the challenges in the theoretical description of photoreceptor proteins using multiscale modeling, as discussed at the CECAM workshop in Tel Aviv, Israel. The participants have identified grand challenges and discussed the development of new tools to address them. Recent progress in understanding representative proteins such as green fluorescent protein, photoactive yellow protein, phytochrome, and rhodopsin is presented, along with methodological developments.

The interplay between chromophore and protein determines the extended excited state dynamics in a single-domain phytochrome.

Phytochromes are a diverse family of bilin-binding photoreceptors that regulate a wide range of physiological processes. Their photochemical properties make them attractive for applications in optogenetics and superresolution microscopy. Phytochromes undergo reversible photoconversion triggered by the Z ⇄ E photoisomerization about the double bond in the bilin chromophore. However, it is not fully understood at the molecular level how the protein framework facilitates the complex photoisomerization dynamics. We have studied a single-domain bilin-binding photoreceptor All2699g1 (Nostoc sp. PCC 7120) that exhibits photoconversion between the red light-absorbing (Pr) and far red-absorbing (Pfr) states just like canonical phytochromes. We present the crystal structure and examine the photoisomerization mechanism of the Pr form as well as the formation of the primary photoproduct Lumi-R using time-resolved spectroscopy and hybrid quantum mechanics/molecular mechanics simulations. We show that the unusually long excited state lifetime (broad lifetime distribution centered at ∼300 picoseconds) is due to the interactions between the isomerizing pyrrole ring D and an adjacent conserved Tyr142. The decay kinetics shows a strongly distributed character which is imposed by the nonexponential protein dynamics. Our findings offer a mechanistic insight into how the quantum efficiency of the bilin photoisomerization is tuned by the protein environment, thereby providing a structural framework for engineering bilin-based optical agents for imaging and optogenetics applications.

Dynamic Properties of the Photosensory Domain of Deinococcus radiodurans Bacteriophytochrome.

Phytochromes are biological photoreceptors found in all kingdoms of life. Numerous physicochemical and spectroscopic studies of phytochromes have been carried out for many decades, both experimentally and computationally, with the main focus on the photoconversion mechanism involving a tetrapyrrole chromophore. In this computational work, we concentrate on the long-scale dynamic motion of the photosensory domain of Deinococcus radiodurans by means of classical all-atom molecular dynamics (MD) simulations. Conventional and accelerated MD methods in combination with two different force fields, CHARMM27 and AMBER ff14SB, are tested in long atomistic simulations to confront the dynamics of monomer and dimer forms. These calculations highlight dissimilar equilibrium conformations in aqueous solutions and, in turn, different large-scale dynamic behaviors of the monomer form vs the dimer form. While the phytochrome in a monomer form tends to close the cavity entailed between the GAF and PHY domains, the opposite trend is predicted for the phytochrome dimer, which opens up as a consequence of the formation of strong salt bridges between the PHY domains of two molecules in water.

The Effective Conjugation Length Is Responsible for the Red/Green Spectral Tuning in the Cyanobacteriochrome Slr1393g3.

The origin of the spectral shift from a red- to a green-absorbing form in a cyanobacteriochrome, Slr1393g3, was identified by combined quantum mechanics/molecular mechanics simulations. This protein, related to classical phytochromes, carries the open-chain tetrapyrrole chromophore phycocyanobilin. Our calculations reveal that the effective conjugation length in the chromophore becomes shorter upon conversion from the red to the green form. This is related to the planarity of the entire chromophore. A large distortion was found for the terminal pyrrole rings A and D; however, the D ring contributes more strongly to the photoproduct tuning, despite a larger change in the twist of the A ring. Our findings implicate that the D ring twist can be exploited to regulate the absorption of the photoproduct. Hence, mutations that affect the D ring twist can lead to rational tuning of the photoproduct absorption, allowing the tailoring of cyanobacteriochromes for biotechnological applications such as optogenetics and bioimaging.