In all organisms, the ribosome synthesizes and folds full length polypeptide chains into active three-dimensional conformations. The nascent protein goes through two major interactions, first with the ribosome which synthesizes the polypeptide chain and holds it for a considerable length of time, and then with the chaperones. Some of the chaperones are found in solution as well as associated to the ribosome. A number of in vitro and in vivo experiments revealed that the nascent protein folds through specific interactions of some amino acids with the nucleotides in the peptidyl transferase center (PTC) in the large ribosomal subunit. The mechanism of this folding differs from self-folding. In this article, we highlight the folding of nascent proteins on the ribosome and the influence of chaperones etc. on protein folding.
Endophytes have been explored and found to perform an important role in plant health. However, their effects on the host physiological function and disease management remain elusive. The present study aimed to assess the potential effects of endophytes, singly as well as in combination, in (L.) Dunal, on various physiological parameters and systemic defense mechanisms against Seeds primed with the endophytic bacteria and individually and in combination demonstrated an enhanced vigor index and germination rate. Interestingly, plants treated with the two-microbe combination showed the lowest plant mortality rate (28%) under stress. Physiological profiling of treated plants showed improved photosynthesis, respiration, transpiration, and stomatal conductance under pathogenic stress. Additionally, these endophytes not only augmented defense enzymes and antioxidant activity in treated plants but also enhanced the expression of salicylic acid- and jasmonic acid-responsive genes in the stressed plants. Reductions in reactive oxygen species (ROS) and reactive nitrogen species (RNS) along with enhanced callose deposition in host plant leaves corroborated well with the above findings. Altogether, the study provides novel insights into the underlying mechanisms behind the tripartite interaction of endophyte-- and underscores their ability to boost plant health under pathogen stress. is well known for producing several medicinally important secondary metabolites. These secondary metabolites are required by various pharmaceutical sectors to produce life-saving drugs. However, the cultivation of faces severe challenge from leaf spot disease caused by To keep pace with the rising demand for this plant and considering its capacity for cultivation under field conditions, the present study was undertaken to develop approaches to enhance production of through intervention using endophytes. Application of bacterial endophytes not only suppresses the pathogenicity of but also mitigates excessive ROS/RNS generation via enhanced physiological processes and antioxidant machinery. Expression profiling of plant defense-related genes further validates the efficacy of bacterial endophytes against leaf spot disease.
The peptidyl transferase center, present in domain V of 23S rRNA of eubacteria and large rRNA of plants and animals, can act as a general protein folding modulator. Here we show that a few specific nucleotides in Escherichia coli domain V RNA bind to unfolded proteins and, as shown previously, bring the trapped proteins to a folding-competent state before releasing them. These nucleotides are the same for the proteins studied so far: bovine carbonic anhydrase, lactate dehydrogenase, malate dehydrogenase, and chicken egg white lysozyme. The amino acids that interact with these nucleotides are also found to be specific in the two cases tested: bovine carbonic anhydrase and lysozyme. They are either neutral or positively charged and are present in random coils on the surface of the crystal structure of both the proteins. In fact, two of these amino acid-nucleotide pairs are identical in the two cases. How these features might help the process of protein folding is discussed.Ribosomes from various sources have shown protein-folding activity in vitro (1,13,14,23). This activity was tested on more than a dozen proteins with various tertiary structures and organizations (1,7,14,20). The activity was found later to be present in the large ribosomal subunit, and on stripping ribosomes of their proteins, it could be assigned to the peptidyl transferase center (PTC) in the larger RNA of the large subunit (8,11,30,35). In Escherichia coli and in other eubacteria in general, the PTC is in domain V (U2016 to G2625 of E. coli) of 23S rRNA.If the same RNA can fold a large number of proteins which are structurally unrelated, the question of specificity arises in the interaction of the unfolded proteins with the RNA. Here we have deciphered the RNA-protein interactions at the nucleotide-amino acid level.To locate the interacting nucleotides of domain V, we used primer extension analysis and determined the positions where the extensions were blocked. We found that the same set of nucleotides interacts with four different proteins tested: bovine carbonic anhydrase (BCA), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), and chicken egg white lysozyme. Using matrix-assisted laser desorption ionization-time of flight/time of flight (MALDI-TOF/TOF), we also tested whether the RNA interacted with specific amino acids. In the two proteins tested, BCA and lysozyme, the amino acids involved were specific for each protein and could even be identical between the two proteins. The disposition of the amino acids on the three-dimensional structure shared some common features. The RNA-protein interactions thus appear to have significant specificity. MATERIALS AND METHODSIn vitro synthesis of domain V of E. coli 23S rRNA. The rRNA gene fragment containing domain V was cloned in vector pTZ57R/T (Fermentas) under the control of a T7 promoter. The presence of the domain in selected clones was verified by DNA sequencing. An EcoRI restriction site, just downstream of the domain, was used to linearize the plasmid, and RNA was synthesized using ...
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