China
Africa
Explore chapters and articles related to this topic
Structures
Published in Thomas M. Nordlund, Peter M. Hoffmann, Quantitative Understanding of Biosystems, 2019
Thomas M. Nordlund, Peter M. Hoffmann
Transfer RNA (tRNA) is a small RNA molecule (74–95 nucleotides) that transfers a specific amino acid to a growing polypeptide chain at ribosome where a new protein is being assembled. Figure 5.38 shows a phenylalanine tRNA from yeast. It has a 3′ terminal site for amino acid attachment. The amino acid is covalently attached by an enzyme, aminoacyl tRNA synthetase. A three-base region called the anticodon that base pairs to the corresponding three-base codon on mRNA is marked at the bottom of the figure. The anticodon for Phe is AAG. Each type of tRNA molecule can be attached to only one type of amino acid, but because several different codons can specify some amino acids, tRNA molecules with different anticodons may carry the same amino acid. tRNA is L-shaped and narrow in the direction normal to the view of Figure 5.38. The narrowness is needed because two tRNA molecules must bind near the same site at the ribosome. tRNA contains regions that are base paired and stacked and loops that have partially stacked, but nonpaired bases. These regions enable recognition by enzymes that bind to specific tRNAs.
Proteins and proteomics
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2018
Translation is the first stage of protein biosynthesis, and this is a part of the overall process of gene expression. It is the production of proteins by decoding mRNA produced in transcription. It also occurs in the cytoplasm where the ribosomes are located. Ribosomes are made of a small subunit and a large subunit, which surround the mRNA. In translation, messenger RNA is decoded to produce a specific polypeptide according to the rules specified by the genetic code. This uses an mRNA sequence as a template to guide the synthesis of a chain of amino acids that form a protein. Many types of transcribed RNA, such as transfer RNA, ribosomal RNA, and small nuclear RNA are not necessarily translated into an amino acid sequence (Figure 3.5).
New Strategies to Discover Non-Ribosomal Peptides as a Source of Antibiotics Molecules
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Mario Alberto Martínez-Núñez, Zuemy Rodríguez-Escamilla, Víctor López y López
The second antibiotic resistance mechanism are structural modifications of antibiotic targets, such as the PBPs and ribosomes, avoiding that antibiotics bind specifically to them with high affinity conferring resistance to antibiotics (Blair et al., 2015). The ribosome is one of the main targets of antibiotic in the cell, since a wide variety of natural, semisynthetic or synthetic antibiotics inhibit the proliferation of pathogenic bacteria by binding to their ribosomes and interfering with translation (Tenson and Mankin, 2006). An example of this type of mechanism is the resistance to oxazolidinones, which are heterocyclic organic compounds that function as protein synthesis inhibitors. It have been described three classes of resistance to oxazolidinone: mutations in the 23S rRNA central loop domain V (peptidyl transferase center) which lead to small conformational changes of the linezolid binding pocket affecting drug binding; the second is a less common mechanism that involves mutations in the genes rplC and rplD that encode 50S ribosomal proteins L3 and L4, respectively; and the last is the acquisition of the ribosomal methyltransferase gene cfr (chloramphenicol-florfenicol resistance) (Chellat et al., 2016). The Cfr protein, through C8 methylation of the residue A2503Ec in the 23S rRNA, reduces susceptibility to antibiotics such amphenicols, lincosamides, pleuromutilins, streptogramin A, 16-membered macrolides, and linezolid (Smith and Mankin, 2008; Chellat et al., 2016). In Gram-positive organisms, structural modifications of the cell wall or cytosolic components such as ribosomes are the main mechanism of resistance and not those due to the enzymatic mechanisms.
Psychrotolerant Antarctic bacteria biosynthesize gold nanoparticles active against sulphate reducing bacteria
Published in Preparative Biochemistry & Biotechnology, 2020
Kirti Ranjan Das, Anoop Kumar Tiwari, Savita Kerkar
DNA breakage was visually detected as the difference in DNA migration i.e., comet type migration pattern in the slides. Genotoxic effect on SRB assessed by comet assay showing the normal cell with intact DNA in Figure 4a and comet pattern migration (Figure 4b) indicated DNA damage in the cells. The percentage of DNA in the tail of comet was measured with CASP comet assay image analysis software to asses DNA damage in SRB and was found to increase from 4% to 59% with the increase in GNP concentration (Figure 4c). In this study, anaerobic bacterial growth decreased with an increased nanoparticle dose concentration with a simultaneous increase in DNA damage percentage. The genotoxicity study provided evidence for the internalization of GNP into the cell and affecting the genetic materials. Due to the nano-dimension, it can easily penetrate through the cell membrane and may possibly react with various cellular organelles in the cytoplasm and cause damage to the DNA of cell or directly attack the genetic material thus interrupting different activities of the cell. Cui et al.[39] reported that the molecular action of GNP was through inhibition in the tRNA binding of the subunit of ribosome, thus collapsing its biological mechanism. From SEM analysis and comet assay, it was evident that in this study the mode of action for inhibiting SRB growth was due to induction of DNA damage by GNP.
Cloning, expression and characterization of a HER2-alpha luffin fusion protein in Escherichia coli
Published in Preparative Biochemistry and Biotechnology, 2019
Farzaneh Barkhordari, Nooshin Sohrabi, Fatemeh Davami, Fereidoun Mahboudi, Yeganeh Talebkhan Garoosi
Anticancer monoclonal antibodies usually have low cytotoxicity which can be overcome through conjugation to the chemical or biological elements for targeting subcellular targets.[30] Conjugated monoclonal antibodies (chemical or toxins) are developed to take the synergic advantages of targeted therapy and cytotoxicity. In recent decades, Ribosome Inactivating Proteins (RIPs) as potential valuable therapeutic and research agents have attracted significant attention due to their interactions with ribosomes and prevention of protein synthesis which may result in cancer cell death.[31,32] Based on their cytotoxic nature, RIP conjugated molecules (e.g. antibodies, cytokines, and proteins) have been used in targeting specific various cell populations.[33,34] In the present study, we designed a novel fusion protein containing mature alpha luffin protein as a RIP I molecule fused to the anti-HER2 scFv antibody fragment derived from trustuzumab, as a monoclonal antibody which is used commonly worldwide.
It's not just about protein turnover: the role of ribosomal biogenesis and satellite cells in the regulation of skeletal muscle hypertrophy
Published in European Journal of Sport Science, 2019
Matthew Stewart Brook, Daniel James Wilkinson, Ken Smith, Philip James Atherton
Protein synthesis is the process by which ribosomes create polypeptide chains through linking amino acids together in a specific order according to mRNA. As such, rates of protein synthesis can be modulated by the rate of mRNA translation, known as “translational efficiency”. A primary control point regulating translational efficiency and therefore protein synthesis in the majority of eukaryotic cells is by cap dependent translation. This involves the assembly of many eukaryotic initiation factors (eIF's) to form a preinitiation complex (PIC) that interacts with the 5′ end of an mRNA to instigate protein synthesis (for more detail readers are directed to [Jackson, Hellen, & Pestova, 2010]). However, with protein synthesis being an energy demanding processes (e.g. through peptide bonding) it is unsurprising that there is myriad of regulating signaling cascades, many of which culminate on the mammalian target of rapamycin (mTOR), that integrates signals such as exercise, AA availability and energy status to coordinate cellular metabolism (Goodman et al., 2011). Some of the best understood targets of mTOR are those directly involved in cap-dependent translation, including P70S6K1, 4E-BP1, and RPS6 that can enhance translation initiation and efficiency in the absence of ribosomal biogenesis (Chesley, MacDougall, Tarnopolsky, Atkinson, & Smith, 1992).