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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Three mutations repurpose a plant karrikin receptor to a strigolactone receptor

Significance Parasitic plants like witchweed cause huge losses in crop yield in Africa. A key part to the success of witchweed is to start its life cycle upon sensing small molecules called strigolactones, which are exuded from roots of host plants into the soil. Witchweed sense host-derived strigolactones through receptors called HTLs. It is thought that the evolutionary origin of HTLs is a receptor called KAI2 in nonparasitic plants, which can respond to different small molecules such as karrikins. By making three changes in the protein sequence of KAI2, this hybrid receptor can now sense both strigolactones and karrikins. These results help in understanding how receptors can evolve to sense different signals and can lead to solutions for combating pesky witchweed.

Arellano-Saab, Amir↗
DOE OSTI2021

Neural networks to learn protein sequence–function relationships from deep mutational scanning data

Understanding the relationship between protein sequence and function is necessary to design new and useful proteins with applications in bioenergy, medicine, and agriculture. The mapping from sequence to function is tremendously complex because it involves thousands of molecular interactions that are coupled over multiple lengths and timescales. We show that neural networks can learn the sequence–function mapping from large protein datasets. Neural networks are appealing for this task because they can learn complicated relationships from data, make few assumptions about the nature of the sequence–function relationship, and can learn general rules that apply across the length of the protein sequence. We demonstrate that learned models can be applied to design new proteins with properties that exceed natural sequences.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

A G protein alpha null mutation confers prolificacy potential in maize

Plasticity in plant development is controlled by environmental signals through largely unknown signalling networks. Signalling coupled by the heterotrimeric G protein complex underlies various developmental pathways in plants. The morphology of two plastic developmental pathways, root system architecture and female inflorescence formation, was quantitatively assessed in a mutant compact plant 2 (ct2) lacking the alpha subunit of the heterotrimeric G protein complex in maize. The ct2 mutant partially compensated for a reduced shoot height by increased total leaf number, and had far more ears, even in the presence of pollination signals. Lastly, the maize heterotrimeric G protein complex is important in some plastic developmental traits in maize. In particular, the maize Gα subunit is required to dampen the overproduction of female inflorescences.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Mutation-driven RRE stem-loop II conformational change induces HIV-1 nuclear export dysfunction

Abstract The Rev response element (RRE) forms an oligomeric complex with the viral protein Rev to facilitate the nuclear export of intron-retaining viral RNAs during the late phase of HIV-1 (human immunodeficiency virus type 1) infection. However, the structures and mechanisms underlying this process remain largely unknown. Here, we determined the crystal structure of the HIV-1 RRE stem-loop II (SLII), revealing a unique three-way junction architecture in which the base stem (IIa) bifurcates into the stem-loops (IIb and IIc) to compose Rev binding sites. The crystal structures of various SLII mutants demonstrated that while some mutants retain the same “compact” fold as the wild type, other single-nucleotide mutants induce drastic conformational changes, forming an “extended” SLII structure. Through in vitro Rev binding assays and Rev activity measurements in HIV-1-infected cells using structure-guided SLII mutants designed to favor specific conformers, we showed that while the compact fold represents a functional SLII, the alternative extended conformation inhibits Rev binding and oligomerization and consequently stimulates HIV-1 RNA nuclear export dysfunction. The propensity of SLII to adopt multiple conformations as captured in crystal structures and their influence on Rev oligomerization illuminate emerging perspectives on RRE structural plasticity-based regulation of HIV-1 nuclear export and provide opportunities for developing anti-HIV drugs targeting specific RRE conformations.

Biochemistry & Molecular Biology↗
DOE OSTI2018

5-Formylcytosine mediated DNA–protein cross-links block DNA replication and induce mutations in human cells

Nucleic Acids Research, 46(13):6455–6469, https://doi.org/10.1093/nar/gky444. There was a typographical error on page 6458, column 1, line 12 and on page 6459, column 2, line 53. In both instances, dNTP concentrations should be listed as ‘5, 10, 25, 50, 100, 150, 250, 500 μM’. The same error has been corrected in the labels of Supplementary Figure S2. These typos do not affect the kinetics parameters listed in Table 2 and do not influence the results and conclusions of the article. The article and supplementary file have been updated.

59 BASIC BIOLOGICAL SCIENCES↗