Biologists show inner workings of cellular 'undertaker'

The 26S proteasome is the primary eukaryotic degradation machine and thus is critically involved in numerous cellular processes. The heterohexameric adenosine triphosphatase (ATPase) motor of the proteasome unfolds and translocates targeted protein substrates into the open gate of a proteolytic core while a proteasomal deubiquitinase concomitantly removes substrate-attached ubiquitin chains. However, the mechanisms by which ATP hydrolysis drives the conformational changes responsible for these processes have remained elusive. Here we present the cryo–electron microscopy structures of four distinct conformational states of the actively ATP-hydrolyzing, substrate-engaged 26S proteasome. These structures reveal how mechanical substrate translocation accelerates deubiquitination and how ATP-binding, -hydrolysis, and phosphate-release events are coordinated within the AAA+ (ATPases associated with diverse cellular activities) motor to induce conformational changes and propel the substrate through the centra

Biologists show inner workings of cellular 'undertaker'

One of a cell's most important responsibilities is to break down and recycle proteins that are no longer needed or endanger the cell. This task is carried out by a cellular nanomachine called ...

Tue 4 Dec 18 from Phys.org

Biologists show inner workings of cellular 'undertaker', Tue 4 Dec 18 from Eurekalert

Substrate-engaged 26S proteasome structures reveal mechanisms for ATP-hydrolysis-driven translocation

The 26S proteasome is the primary eukaryotic degradation machine and thus is critically involved in numerous cellular processes. The heterohexameric adenosine triphosphatase (ATPase) motor ...

Thu 29 Nov 18 from Science Now

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