Systematic analysis of tRNA transcription unit deletions in E. coli reveals insights into tRNA gene essentiality and cellular adaptation.

Transfer ribonucleic acids (tRNAs) are essential for protein synthesis, decoding mRNA sequences into amino acids. In E. coli K-12 MG1655, 86 tRNA genes are organized in 43 transcription units (TUs) and the essentiality of individual tRNA TUs in bacterial physiology remains unclear.

A microbiological system for screening the interference of XNA monomers with DNA and RNA metabolism.

We explored the toxicity and mutagenicity of a wide range of xenobiotic nucleoside triphosphates to an strain equipped with a nucleoside triphosphate transporter. This bacterial test provides a tool to evaluate and guide the synthesis of nucleotides for applications such as the propagation of non-natural genetic information or the selection of potential drugs.

Noncanonical DNA polymerization by aminoadenine-based siphoviruses.

Bacteriophage genomes harbor the broadest chemical diversity of nucleobases across all life forms. Certain DNA viruses that infect hosts as diverse as cyanobacteria, proteobacteria, and actinobacteria exhibit wholesale substitution of aminoadenine for adenine, thereby forming three hydrogen bonds with thymine and violating Watson-Crick pairing rules. Aminoadenine-encoded DNA polymerases, homologous to the Klenow fragment of bacterial DNA polymerase I that includes 3'-exonuclease but lacks 5'-exonuclease, were found to preferentially select for aminoadenine instead of adenine in deoxynucleoside triphosphate incorporation templated by thymine.

Invading Genetics with a Xenobiotic Nucleic Acid Carrying an Acyclic Phosphonate Backbone (ZNA).

A synthetic orthogonal polymer embracing a chiral acyclic-phosphonate backbone [()-ZNA] is presented that uniquely adds to the emerging family of xenobiotic nucleic acids (XNAs). ()-ZNA consists of reiterating six-atom structural units and can be accessed in few synthetic steps from readily available phophonomethylglycerol nucleoside (PMGN) precursors. Comparative thermal stability experiments conducted on homo- and heteroduplexes made of ()-ZNA are described that evince its high self-hybridization efficiency in contrast to poor binding of natural complements.

Methylated Nucleobases: Synthesis and Evaluation for Base Pairing In Vitro and In Vivo.

The synthesis, base pairing properties and in vitro (polymerase) and in vivo (E. coli) recognition of 2'-deoxynucleotides with a 2-amino-6-methyl-8-oxo-7,8-dihydro-purine (X), a 2-methyl-6-thiopurine (Y) and a 6-methyl-4-pyrimidone (Z) base moiety are described. As demonstrated by T measurements, the X and Y bases fail to form a self-complementary base pair.