Mass Spec Roundup: Sulfur, Stars and Sequencing…

Sulfur From the Sky

Earth’s early atmosphere may have supplied essential chemical ingredients for life long before the first organisms emerged, according to a new study in PNAS. Researchers at the University of Colorado Boulder recreated the conditions of the planet’s primordial sky and discovered that it could generate a surprising collection of biologically relevant sulfur molecules – including cysteine, taurine, and coenzyme M, compounds long assumed to arise only through living systems.

The team shone light onto mixtures of methane, carbon dioxide, nitrogen, and hydrogen sulfide to simulate early atmospheric chemistry. Because sulfur molecules form at extraordinarily low concentrations, the researchers relied on a highly sensitive mass spectrometer to detect trace quantities of newly formed products. “Our study could help us understand the evolution of life at its earliest stages,” said first author Nate Reed, who carried out the work at CU Boulder’s Department of Chemistry and CIRES.

The results challenge the long-standing assumption that sulfur biomolecules were “invented” only after life appeared. When scaled to planetary levels, the atmospheric reactions could have produced enough cysteine to supply roughly one octillion cells – a substantial reservoir for a lifeless world.

According to senior author Ellie Browne, these compounds may have fallen with rain into oceans or onto volcanic landscapes where early biochemical pathways were forming. “Our results suggest some of these more complex molecules were already widespread under non-specialized conditions, which might have made it a little easier for life to get going.”

Precise Masses Refine X-Ray Burst Nucleosynthesis

Physicists in China have made the most precise measurements to date of two extremely short-lived nuclei – phosphorus-26 and sulfur-27 – providing long-sought data needed to predict how elements form during explosive X-ray bursts on neutron stars. The research, carried out at the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences, delivers essential input for calculating the proton-capture reaction rates that drive these thermonuclear events.

Using a magnetic-rigidity–defined isochronous mass spectrometry setup at the Cooling Storage Ring in Lanzhou, the team directly determined the masses of the rare isotopes, showing that sulfur-27 is more tightly bound than previously thought. The improved precision – an eightfold reduction in uncertainty – sharply refines the proton separation energy, a quantity that governs how rapidly the rp-process builds heavier nuclei during a burst.

According to Yan Xinliang of IMP, “the significance of a potential reaction branch involving phosphorus-26 and sulfur-27 in the rp-process has been debated for years due to the lack of precise mass data for these nuclei.”

“Our high-precision mass results and the corresponding new reaction rate provide more reliable input for astrophysical reaction networks, resolving the uncertainties in the nucleosynthesis pathways within the phosphorus-sulfur region of X-ray bursts,” added co-corresponding author Hou Suqing.

Parallel Protein Profiling with PLAMseq

Researchers at the Andalusian Centre for Molecular Biology and Regenerative Medicine (CABIMER) have developed proximity-labelled affinity-purified mass spectrometry plus sequencing (PLAMseq): a technique that, for the first time, enables scientists to simultaneously analyze which proteins bind chromatin and where they act in the genome in a single experiment. The breakthrough, published in Science Advances, removes the need for multiple labor-intensive methods such as ChIP-seq and traditional mass spectrometry workflows.

PLAMseq relies on TurboID, a rapid biotinylation enzyme that tags proteins directly at their genomic locations, allowing researchers to isolate both the proteins and the DNA fragments they are bound to. Using this approach, the team mapped essential chromatin regulators including CTCF, RNA polymerase II, and SUMO-modified H1 histones, uncovering previously unknown interactions such as SETDB1 binding to modified histones.

Beyond the strong technical performance, the authors emphasize the biological power of the method. “With PLAMseq, we can observe, in a single experiment, the dual dimension of genome biology: the proteins that shape it and the regions where they act,” explained Román González-Prieto in the University of Seville’s press release. “This opens up a whole new horizon for understanding how deregulation of these interactions contributes to human diseases.

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