Peking University Bai Fan’s teamwork results: Liquid-liquid separation and membraneless liquid protein aggregates analysis in bacteria

Two distinct liquid layers appear in a mixed solution—for example, when oil and vinegar are separated in salad dressings—physicists call this liquid-liquid separation (LLPS)

Protein aggregates in bacteria have been identified for decades, but their functional role is still controversial

Fan Bai, a biophysicist at Peking University and Mark Leake of the University of York, have previously demonstrated that when bacteria are under the pressure of antibiotic therapy or the availability of ATP (a form of molecular energy) When reduced, they form protein aggregates in E.

The research team used fluorescently labeled proteins, which have been shown in aggregates before.

Aggregates shown by fluorescently labeled proteins (red and green) form

Further evidence suggests that, unlike previously reported protein aggregates formed by misfolded proteins, aggresomes are dynamic and reversible structures that form under stress and break down when cells undergo fresh growth medium

Although the research team does not yet know how these aggregates are formed, they suspect that this may be related to ATP itself

Researchers used experiments and multi-scale modeling to determine the molecular biophysics of its spatial and temporal control, and infer the key role of aggresomes in bacterial fitness

The study also analyzed the effects of aggresomes on bacterial survival

How bacterial cells detect stress and respond to stress specifically and timely is an important issue

Frederic Rousseau, a researcher on protein aggregation at the University of Leuven in Belgium, did not participate in the study.

University of Michigan chemist and biophysicist Julie Biteen (Julie Biteen) said that traditional microscopy methods have revealed that there may be protein aggregation in bacteria caused by liquid phase separation (the so-called condensates ), but understand them The formation mechanism of and whether they are liquid or solid has always been a real challenge

Stephanie Weber of McGill University studies the spatial organization of cells, but did not participate in this research

The research team further proved that these aggregates are not unique to E.