Read by QxMD icon Read


Guillaume F Chanfreau
No abstract text is available yet for this article.
2017: Enzymes
Ya-Ming Hou, Ryuma Matsubara, Ryuichi Takase, Isao Masuda, Joanna I Sulkowska
TrmD is an S-adenosyl methionine (AdoMet)-dependent methyl transferase that synthesizes the methylated m(1)G37 in tRNA. TrmD is specific to and essential for bacterial growth, and it is fundamentally distinct from its eukaryotic and archaeal counterpart Trm5. TrmD is unusual by using a topological protein knot to bind AdoMet. Despite its restricted mobility, the TrmD knot has complex dynamics necessary to transmit the signal of AdoMet binding to promote tRNA binding and methyl transfer. Mutations in the TrmD knot block this intramolecular signaling and decrease the synthesis of m(1)G37-tRNA, prompting ribosomes to +1-frameshifts and premature termination of protein synthesis...
2017: Enzymes
Katherine M McKenney, Mary Anne T Rubio, Juan D Alfonzo
All types of nucleic acids in cells undergo naturally occurring chemical modifications, including DNA, rRNA, mRNA, snRNA, and most prominently tRNA. Over 100 different modifications have been described and every position in the purine and pyrimidine bases can be modified; often the sugar is also modified [1]. In tRNA, the function of modifications varies; some modulate global and/or local RNA structure, and others directly impact decoding and may be essential for viability. Whichever the case, the overall importance of modifications is highlighted by both their evolutionary conservation and the fact that organisms use a substantial portion of their genomes to encode modification enzymes, far exceeding what is needed for the de novo synthesis of the canonical nucleotides themselves [2]...
2017: Enzymes
Guillaume F Chanfreau
Constitutive and regulated turnover of RNAs is necessary to eliminate aberrant RNA molecules and control the level of specific mRNAs to maintain homeostasis or to respond to signals in living cells. Modifications of nucleosides in specific RNAs are important in modulating the functions of these transcripts, but they can also dramatically impact their fate and turnover. This chapter will review how RNA modifications impact the activities of ribonucleases that target these RNAs for degradation or cleavage, focusing more particularly on tRNAs and mRNAs in eukaryotic cells...
2017: Enzymes
Lee E Vandivier, Brian D Gregory
Ribonucleotides can be covalently modified with over 100 known chemical moieties, greatly expanding the potential coding and regulatory repertoire of RNA. Recent advances in applying high-throughput sequencing to the study of RNA modifications have generated transcriptome-wide modification maps and demonstrated that modifications are abundant features of multiple classes of RNAs, including messenger RNAs. In turn, new regulatory functions for RNA modifications have been elucidated. Here, we review both targeted and global methods for surveying RNA modification, with a focus on how transcriptome-wide methods have helped expand the understanding of modification-mediated regulation of the transcriptome...
2017: Enzymes
Yuru Wang, Yuxuan Zheng, Peter A Beal
Inosine is one of the most common modifications found in human RNAs and the Adenosine Deaminases that act on RNA (ADARs) are the main enzymes responsible for its production. ADARs were first discovered in the 1980s and since then our understanding of ADARs has advanced tremendously. For instance, it is now known that defective ADAR function can cause human diseases. Furthermore, recently solved crystal structures of the human ADAR2 deaminase bound to RNA have provided insights regarding the catalytic and substrate recognition mechanisms...
2017: Enzymes
Anthony K Henras, Célia Plisson-Chastang, Odile Humbert, Yves Romeo, Yves Henry
Ribosomal RNAs contain numerous 2'-O-methylated nucleosides and pseudouridines. Methylation of the 2' oxygen of ribose moieties and isomerization of uridines into pseudouridines are catalyzed by C/D and H/ACA small nucleolar ribonucleoprotein particles, respectively. We review the composition, structure, and mode of action of archaeal and eukaryotic C/D and H/ACA particles. Most rRNA modifications cluster in functionally crucial regions of the rRNAs, suggesting they play important roles in translation. Some of these modifications promote global translation efficiency or modulate translation fidelity...
2017: Enzymes
Meemanage D De Zoysa, Yi-Tao Yu
Pseudouridine (Ψ) is the most abundant posttranscriptional modification in noncoding RNAs. Pseudouridines are often clustered in important regions of rRNAs (ribosomal RNAs), snRNAs (small nuclear RNAs), and tRNAs (transfer RNAs), contributing to RNA function. Pseudouridylation is governed by two independent mechanisms. The first involves single protein enzymes called pseudouridine synthases (PUSs) that alone recognize the substrate and catalyze the isomerization of uridine to pseudouridine (RNA-independent pseudouridylation)...
2017: Enzymes
Olga Kolaj-Robin, Bertrand Séraphin
Elongator is a highly conserved eukaryotic protein complex consisting of two sets of six Elp proteins, while homologues of its catalytic subunit Elp3 are found in all the kingdoms of life. Although it was originally described as a transcription elongation factor, cumulating evidence suggests that its primary function is catalyzing tRNA modifications. In humans, defects in Elongator subunits are associated with neurological disorders and cancer. Although further studies are still required, a clearer picture of the molecular mechanism of action of Elongator and its cofactors has started to emerge within recent years that have witnessed significant development in the field...
2017: Enzymes
Paul F Agris, Amithi Narendran, Kathryn Sarachan, Ville Y P Väre, Emily Eruysal
The posttranscriptional modifications of tRNA's anticodon stem and loop (ASL) domain represent a third level, a third code, to the accuracy and efficiency of translating mRNA codons into the correct amino acid sequence of proteins. Modifications of tRNA's ASL domain are enzymatically synthesized and site specifically located at the anticodon wobble position-34 and 3'-adjacent to the anticodon at position-37. Degeneracy of the 64 Universal Genetic Codes and the limitation in the number of tRNA species require some tRNAs to decode more than one codon...
2017: Enzymes
Chentao Lin, Sheng Luan, Fuyuhiko Tamanoi
No abstract text is available yet for this article.
2016: Enzymes
D Chandran, M C Wildermuth
Recent studies have revealed that several mutualistic and parasitic biotrophic microbes induce a cell cycle variant termed the endocycle in host cells to support their growth and reproduction. Endoreduplication is a process in which cells successively replicate their genomes without mitosis resulting in an increase in nuclear DNA ploidy. Depending on the interaction, endoreduplication can support biotroph colonization and feeding structure initiation/development, and/or serve as a mechanism to support enhanced metabolic demands of the microbe...
2016: Enzymes
S K Sanyal, S Rao, L K Mishra, M Sharma, G K Pandey
At any given time and location, plants encounter a flood of environmental stimuli. Diverse signal transduction pathways sense these stimuli and generate a diverse array of responses. Calcium (Ca(2+)) is generated as a second messenger due to these stimuli and is responsible for transducing the signals downstream in the pathway. A large number of Ca(2+) sensor-responder components are responsible for Ca(2+) signaling in plants. The sensor-responder complexes calcineurin B-like protein (CBL) and CBL-interacting protein kinases (CIPKs) are pivotal players in Ca(2+)-mediated signaling...
2016: Enzymes
X Liu, S Yang, C-W Yu, C-Y Chen, K Wu
Reversible histone acetylation and deacetylation at the N-terminus of histone tails play a crucial role in regulation of gene activity. Hyperacetylation of histones relaxes chromatin structure and is associated with transcriptional activation, whereas hypoacetylation of histones induces chromatin compaction and gene repression. Histone acetylation and deacetylation are catalyzed by histone acetyltransferases (HATs) and histone deacetylases (HDACs), respectively. Emerging evidences revealed that plant HATs and HDACs play essential roles in regulation of gene expression in plant development and plant responses to environmental stresses...
2016: Enzymes
D Wang, A Fu
Mitochondria possess oxygen-consuming respiratory electron transfer chains (RETCs), and the oxygen-evolving photosynthetic electron transfer chain (PETC) resides in chloroplasts. Evolutionarily mitochondria and chloroplasts are derived from ancient α-proteobacteria and cyanobacteria, respectively. However, cyanobacteria harbor both RETC and PETC on their thylakoid membranes. It is proposed that chloroplasts could possess a RETC on the thylakoid membrane, in addition to PETC. Identification of a plastid terminal oxidase (PTOX) in the chloroplast from the Arabidopsis variegation mutant immutans (im) demonstrated the presence of a RETC in chloroplasts, and the PTOX is the committed oxidase...
2016: Enzymes
K He, Y Wu
Plants are sessile organisms exposed constantly to potential virulent microbes seeking for full pathogenesis in hosts. Different from animals employing both adaptive and innate immune systems, plants only rely on innate immunity to detect and fight against pathogen invasions. Plant innate immunity is proposed to be a two-tiered immune system including pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity. In PTI, PAMPs, the elicitors derived from microbial pathogens, are perceived by cell surface-localized proteins, known as pattern recognition receptors (PRRs), including receptor-like kinases (RLKs) and receptor-like proteins (RLPs)...
2016: Enzymes
E Saplaoura, F Kragler
Phloem serves as a highway for mobile signals in plants. Apart from sugars and hormones, proteins and RNAs are transported via the phloem and contribute to the intercellular communication coordinating growth and development. Different classes of RNAs have been found mobile and in the phloem exudate such as viral RNAs, small interfering RNAs (siRNAs), microRNAs, transfer RNAs, and messenger RNAs (mRNAs). Their transport is considered to be mediated via ribonucleoprotein complexes formed between phloem RNA-binding proteins and mobile RNA molecules...
2016: Enzymes
Laurie S Kaguni, Marcos Túlio Oliveira, Fuyuhiko Tamanoi
No abstract text is available yet for this article.
2016: Enzymes
C E Cameron, I M Moustafa, J J Arnold
Using poliovirus (PV) and its RNA-dependent RNA polymerase (RdRp) as our primary model system, we have advanced knowledge fundamental to the chemistry and fidelity of nucleotide addition by nucleic acid polymerase. Two fidelity checkpoints exist prior to nucleotide addition. The first toggles the enzyme between a nucleotide binding-occluded state and a nucleotide binding-competent state. The second represents an ensemble of conformational states of conserved structural motifs that permits retention of the incoming nucleotide in a state competent for phosphoryl transfer long enough for chemistry to occur...
2016: Enzymes
G L Ciesielski, M T Oliveira, L S Kaguni
Recent advances in the field of mitochondrial DNA (mtDNA) replication highlight the diversity of both the mechanisms utilized and the structural and functional organization of the proteins at mtDNA replication fork, despite the relative simplicity of the animal mtDNA genome. DNA polymerase γ, mtDNA helicase and mitochondrial single-stranded DNA-binding protein-the key replisome proteins, have evolved distinct structural features and biochemical properties. These appear to be correlated with mtDNA genomic features in different metazoan taxa and with their modes of DNA replication, although substantial integrative research is warranted to establish firmly these links...
2016: Enzymes
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"