Team identifies ancient mutation that contributed to evolution of multicellular animals

University of Chicago Medical Center

It acts as a kind of molecular carabiner by binding to two different partner molecules: an ‘anchor’ protein on the inside of the cell membrane that indicates the position of adjacent cells and a motor protein that pulls on mitotic spindle filaments. Our experiments show that the GK-PID evolved its carabiner function early, before multicellularity itself appeared, Thornton said. A deeper analysis of the proteins’ structural biology suggested that the answer lies in a process that Thornton calls molecular exploitation, in which a new molecule (in this case the anchor) fortuitously binds an old protein (GK-PID) because it just happens to be structurally similar to the protein’s original molecular partner. The researchers found that the ancestral GK-PID bound the anchor protein in a very similar way to how the ancestral gk enzyme bound its substrate. We hope that the approach we used – reconstructing in detail the ancient history of protein functions – can be applied to the evolution of other key cellular processes, revealing the whole picture of multicellular life evolving from single-celled ancestors, Thornton said.

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