The atomic structure of the activated human minor spliceosome is reported in Science this week. The minor spliceosome is responsible for splicing a rare but essential intron type known as U12-type introns. Its existence has been known for decades, yet relatively little is known about its composition, functional states, catalysis, and regulation due to its scarcity. Addressing this knowledge gap, Westlake University scientists report the in vitro assembly and purification of the activated human minor spliceosome (minor Bact complex) and determine its structure using cryo-electron microscopy at 2.9-Å resolution, revealing a wealth of information. "Scrutiny of the structural features of the human minor Bact complex — the first of its kind — may reveal additional findings about the minor spliceosome," they write.
The more than 260,000 SARS-CoV-2 sequences that are now publicly available have enabled the scientific community to gain important insights into the virus including the timing of its spillover into humans, how it has spread, and how it has adapted to its new host, a trio of Emory University scientists writes in commentary in this week's Science. Analyzing these sequences has also shown that the virus evolves at a rate corresponding to one substitution about every 11 days and could enable phylodynamic analyses that can be applied to identify future viral adaptation. "The number of available SARS-CoV-2 sequences is, like many things during this pandemic, unprecedented," they write. Gaining understanding from these data is not without challenges, but "continued efforts to collect viral sequence data and the development of efficient and scalable computational inference methods will help to further cement evolutionary analyses as a cornerstone of the public health response to viral spread and adaptation."