Regulation and Site-Specific Covalent Labeling of NSUN2 via Genetic Encoding Expansion

In living organisms, RNA regulates gene expression, cell migration, differentiation, and cell death. 5-Methylcytosine is a post-transcriptional RNA modification in a wide range of RNA species, including messenger RNAs. The addition of m5C to RNA cytosines is enabled by the NSUN enzyme family, a critical RNA methyltransferase. In this study, natural lysines modified with special groups were synthesized. Through two rounds of positive screening and one round of negative screening, we evaluated and identified the MbPylRS-tRNACUA unnatural lysine substitution system, which specifically recognizes lysine with a defined group. Moreover, non-natural lysine substitution at C271 of NSUN2 active site and the subsequent fluorescent labeling was realized through the click reaction. Then, the function of the NSUN2 mutant and its upregulated CDK1 gene as well as its effect on cell proliferation were evaluated. Efficient labeling and regulation of NSUN2 was achieved, laying the basis for further studies on the function and regulatory mechanism of upregulated genes.

Fungal X-Intrinsic Protein Aquaporin from Trichoderma atroviride: Structural and Functional Considerations

The major intrinsic protein (MIP) superfamily is a key part of the fungal transmembrane transport network. It facilitates the transport of water and low molecular weight solutes across biomembranes. The fungal uncharacterized X-Intrinsic Protein (XIP) subfamily includes the full protein diversity of MIP. Their biological functions still remain fully hypothetical. The aim of this study is still to deepen the diversity and the structure of the XIP subfamily in light of the MIP counterparts—the aquaporins (AQPs) and aquaglyceroporins (AQGPs)—and to describe for the first time their function in the development, biomass accumulation, and mycoparasitic aptitudes of the fungal bioagent Trichoderma atroviride. The fungus-XIP clade, with one member (TriatXIP), is one of the three clades of MIPs that make up the diversity of T. atroviride MIPs, along with the AQPs (three members) and the AQGPs (three members). TriatXIP resembles those of strict aquaporins, predicting water diffusion and possibly other small polar solutes due to particularly wider ar/R constriction with a Lysine substitution at the LE2 position. The XIP loss of function in ∆TriatXIP mutants slightly delays biomass accumulation but does not impact mycoparasitic activities. ∆TriatMIP forms colonies similar to wild type; however, the hyphae are slightly thinner and colonies produce rare chlamydospores in PDA and specific media, most of which are relatively small and exhibit abnormal morphologies. To better understand the molecular causes of these deviant phenotypes, a wide-metabolic survey of the ∆TriatXIPs demonstrates that the delayed growth kinetic, correlated to a decrease in respiration rate, is caused by perturbations in the pentose phosphate pathway. Furthermore, the null expression of the XIP gene strongly impacts the expression of four expressed MIP-encoding genes of T. atroviride, a plausible compensating effect which safeguards the physiological integrity and life cycle of the fungus. This paper offers an overview of the fungal XIP family in the biocontrol agent T. atroviride which will be useful for further functional analysis of this particular MIP subfamily in vegetative growth and the environmental stress response in fungi. Ultimately, these findings have implications for the ecophysiology of Trichoderma spp. in natural, agronomic, and industrial systems.

Precise Regulation and Site-specifically Covalent Labeling of NSUN2 Enable by Genetic Encoding Expansion

ABSTRACTRNA plays a critical role in gene expression regulation, cell migration, differentiation, cell death in living organism. 5-Methylcytosine is a post transcriptional RNA modification identified across wide ranges of RNA species including message RNAs. It is reported the addition of m5C to RNA cytosines is enabled by use of NSUN family enzyme, NSUN2 is identified as a critical RNA methyltransferase for adding m5C to mRNA. We demonstrated here that natural lysines modified with special groups were synthesized via chemical synthesis. Through two rounds of positive screening and one round of negative screening, MbPylRS-tRNAcua unnatural lysine substitution system which can specifically recognize lysine with defined group was evaluated and identified. Non-natural lysine substitution at C271 of NSUN2 active site and subsequently fluorescent labeling was realized via so-called click reaction. The function of NSUN2 mutant and its upregulated CDK1 gene and its effect on cell proliferation were also evaluated.

Structure-guided de novo design of α-helical antimicrobial peptide with enhanced specificity

In the present study, the 26-residue peptide sequence Ac-KWKSFLKTFKSAKKTVLHTALKAISS-amide (peptide P) was utilized as the framework to study the effects of introducing hydrophilic amino acid lysine on the nonpolar face of the helix on peptide biological activities. Lysine residue was systematically used to substitute original hydrophobic amino acid at the selected locations on the nonpolar face of peptide P. In order to compensate for the loss of hydrophobicity caused by lysine substitution, leucine was also used to replace original alanine to increase peptide overall hydrophobicity. Hemolytic activity is correlated with peptide hydrophobicity. By introducing lysine on the nonpolar face, we significantly weaken peptide hemolytic activity as well as antimicrobial activity. However, by utilizing leucine to compensate the hydrophobicity, we improve antimicrobial activity against both Gram-negative and -positive bacteria. Peptide self-association ability and hydrophobicity were also determined. This specific rational approach of peptide design could be a powerful method to optimize antimicrobial peptides with clinical potential as peptide antibiotics.