An anthropometric study of intercondylar femur notch with MRI analysis

Background: Anterior cruciate ligament is the most common ligament injury of knee. The bony anatomy of femur and tibia is responsible for normal knee kinematics and static stability. Intercondylar notch dimensions is considered as a significant predictive risk factor for ACL tear. Narrow femoral intercondylar notch width in either sex were major correlating factors. Aim was to evaluate the intercondylar femur notch dimensions in patients of knee injury using magnetic resonance imaging at RD Gardi Medical College, Ujjain, Madhya Pradesh. Methods: This is a prospective study consist of 400 patients carried out from October 2020 to August 2022 in the Department of Orthopaedics, RDGMC Ujjain. All the patients of knee injury including ACL tear and age 18 years to 60 years are included in the study. Patient less than 18 years and more than 60 years were excluded from the study. Dicom radiant software is used as statistical tool to analyse the data. Various intercondylar notch dimensions in different sections are measured using MRI in the dicom software. Results: The cut off values of axial NWI, NSI, NDI as 0.238, 0.662, 0.472 respectively. Conclusions: We conclude that narrow femoral intercondylar notch, lower notch width index increases the risk of an ACL tear in the given population. This would help in identification of people at risk for ACL injuries. Our study provides a comprehensive analysis on the risk factor of ACL tear, which would help in betterment of the patients at danger for anterior cruciate ligament injury. People with decreased notch dimensions should be educated on the high risk of ACL tear and be given proper prophylactic precautions

Multifunctional enzymes in the shikimate pathway

Multifunctional enzymes are instances of natural fusion proteins, possessing multiple catalytic activities. Via the close proximity of their catalytic domains, they take advantage from concentration of the reactants and may feature allosteric regulation and substrate channeling effects. Substantial progress has been made regarding the kinetic mechanisms of individual enzymes, but the knowledge in the areas of multifunctional enzymes and also transient complexes is rather limited. The seven step shikimate pathway, which is a metabolic route to aromatic compounds, has a number of bifunctional, trifunctional, tetrafunctional and pentafunctional fusion proteins in different organisms. Most notable is the pentafunctional AROM complex, which comprises the central five steps of the pathway, which has withstood structural characterization for decades. In this work, we shed light on the pentafunctional AROM complex and the three bifunctional enzymes Tm_AroKB, Fp_AroEK and Mb_AroKE of the shikimate pathway by characterizing them functionally and structurally and comparing them to their monofunctional homologs. For the bifunctional proteins, Tm_AroKB and Fp_AroEK the kinetic analysis revealed that their activity is similar to that reported for their monofunctional counterparts. In addition, the kinetic activity of the truncated monofunctional Tm_AroKKB was found to be similar to Tm_AroKB. Interestingly, no allosteric regulation was observed between the two domains in Tm_AroKB. The kinetic analysis of the K domain of Mb_AroKE revealed that it is slower than the other enzymes in this study. However, the genome of the respective organism Methanoregula boonei also contains a monofunctional Mb_AroK, which might play the major role in the shikimate pathway. All crystal structures of the bifunctional enzymes show rigid inter-domain interfaces, with all the catalytic sites solvent accessible. Tm_AroKB is a dimer both in solution and in crystalline state. Remarkably, it contains an intrinsically bound NAD molecule. In all bifunctional proteins, the structure of the individual domains corresponds to that of the monofunctional homologs. However, the domain arrangement in the structures of Fp_AroEK and Mb_AroKE are different. Both arrangements bring the catalytic sites closer and could be part of potential higher order assemblies. Therefore, we hypothesized that the individual enzymes of the pathway form transient complexes for efficient substrate funneling and regulation. In silico models of such assemblies were generated based on both Fp_AroEK, and Mb_AroKE, via superimposition on the bifunctional proteins 4 Tm_AroKB and At_AroDE. These two models are not identical but they both represent a plausible, compact assembly with all active sites solvent accessible. Finally, we studied the pentafunctional AROM complex. The catalytic turnover of the AROM complex is significantly higher than that of the monofunctional E.coli enzymes. The crystal structure of AROM complex, which was found to be different from both in silico models, shows that its domains are attached to each other via rigid interfaces and that all the catalytic sites are solvent accessible. Using SAXS and XL-MS, we verified that the conformation of the AROM complex is very similar in solution and in crystalline state. In a computational approach, we further mapped the various conformational states of the individual enzymatic domains from the PDB onto the crystal structure, generating a structural ensemble representing the conformational space of the AROM complex. This ensemble reveals that the complex is optimized for spatial compatibility of the domains, allowing all necessary conformational changes during the catalytic cycle to happen without steric clashes between domains. Since the shikimate pathway is absent from mammals, it poses a classical drug target. Until now, only glyphosate is utilized as a herbicide for targeting the shikimate pathway. The insight obtained in this study suggests novel approaches to target the shikimate pathway. Most notable is the conformational space of the AROM complex, which is essential in fungi and protists. By targeting the conformational flexibility of the complex, catalytically necessary conformational transitions could be inhibited, which could result in novel, specific fungicides

Architecture and functional dynamics of the pentafunctional AROM complex

The AROM complex is a multifunctional metabolic machine with ten enzymatic domains catalyzing the five central steps of the shikimate pathway in fungi and protists. We determined its crystal structure and catalytic behavior, and elucidated its conformational space using a combination of experimental and computational approaches. We derived this space in an elementary approach, exploiting an abundance of conformational information from its monofunctional homologs in the Protein Data Bank. It demonstrates how AROM is optimized for spatial compactness while allowing for unrestricted conformational transitions and a decoupled functioning of its individual enzymatic entities. With this architecture, AROM poses a tractable test case for the effects of active site proximity on the efficiency of both natural metabolic systems and biotechnological pathway optimization approaches. We show that a mere colocalization of enzymes is not sufficient to yield a detectable improvement of metabolic throughput

Adjustment of the PIF7-HFR1 transcriptional module activity controls plant shade adaptation

Altres ajuts: CERCA Programme/Generalitat de CatalunyaShade caused by the proximity of neighboring vegetation triggers a set of acclimation responses to either avoid or tolerate shade. Comparative analyses between the shade-avoider Arabidopsis thaliana and the shade-tolerant Cardamine hirsuta revealed a role for the atypical basic-helix-loop-helix LONG HYPOCOTYL IN FR 1 (HFR1) in maintaining the shade tolerance in C. hirsuta, inhibiting hypocotyl elongation in shade and constraining expression profile of shade-induced genes. We showed that C. hirsuta HFR1 protein is more stable than its A. thaliana counterpart, likely due to its lower binding affinity to CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), contributing to enhance its biological activity. The enhanced HFR1 total activity is accompanied by an attenuated PHYTOCHROME INTERACTING FACTOR (PIF) activity in C. hirsuta. As a result, the PIF-HFR1 module is differently balanced, causing a reduced PIF activity and attenuating other PIF-mediated responses such as warm temperature-induced hypocotyl elongation (thermomorphogenesis) and dark-induced senescence. By this mechanism and that of the already-known of phytochrome A photoreceptor, plants might ensure to properly adapt and thrive in habitats with disparate light amounts

Adjustment of the PIF7-HFR1 transcriptional module activity controls plant shade adaptation

Shade caused by the proximity of neighboring vegetation triggers a set of acclimation responses to either avoid or tolerate shade. Comparative analyses between the shade-avoider Arabidopsis thaliana and the shade-tolerant Cardamine hirsuta revealed a role for the atypical basic-helix-loop-helix LONG HYPOCOTYL IN FR 1 (HFR1) in maintaining the shade tolerance in C. hirsuta, inhibiting hypocotyl elongation in shade and constraining expression profile of shade-induced genes. We showed that C. hirsuta HFR1 protein is more stable than its A. thaliana counterpart, likely due to its lower binding affinity to CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), contributing to enhance its biological activity. The enhanced HFR1 total activity is accompanied by an attenuated PHYTOCHROME INTERACTING FACTOR (PIF) activity in C. hirsuta. As a result, the PIF-HFR1 module is differently balanced, causing a reduced PIF activity and attenuating other PIF-mediated responses such as warm temperature-induced hypocotyl elongation (thermomorphogenesis) and dark-induced senescence. By this mechanism and that of the already-known of phytochrome A photoreceptor, plants might ensure to properly adapt and thrive in habitats with disparate light amounts