Detailed Structure of Stress-Response Protein ZAK Revealed, Offering New Drug Development Potential
Researchers from Johns Hopkins University and LMU Munich have successfully resolute a high-resolution, three-dimensional structure of the ZAK protein, a key player in the cellular response to stress caused by ribosome collisions.This breakthrough, published in Nature, provides crucial insights into how ZAK functions and opens avenues for developing more targeted therapies.
ZAK is a kinase protein activated when ribosomes, the cellular machinery responsible for protein synthesis, collide during translation.These collisions signal cellular stress, and ZAK’s activation initiates a protective response. However, understanding how ZAK activates and interacts with ribosomes has remained a challenge.
To overcome this, the research team, led by Dr.Sarah green and Dr. Hana huso of Johns Hopkins, employed a clever strategy. They engineered cells to overproduce inactive ZAK proteins and then used a drug to intentionally induce ribosome collisions, thereby activating the protein. A molecular tag attached to ZAK allowed for the isolation of the activated protein bound to ribosomes.
Using cryo-electron microscopy (cryo-EM), the team painstakingly analyzed hundreds of samples over two years. A breakthrough came when LMU graduate student Shuangshuang Niu identified a promising result revealing approximately one-third of ZAK’s structure. This finding was later confirmed by Roland Beckmann, principal investigator at LMU.
The revealed structure indicates that ZAK is largely unstructured, resembling ”spaghetti,” with more defined, structured regions. Scientists hypothesize that the unstructured portion acts like a flexible arm, allowing ZAK to detect colliding ribosomes. The protein appears to bridge the gap between two collided ribosomes, initiating its activation.
Detailed analysis revealed specific interactions between ZAK and the ribosome. The C-terminus of ZAK consistently binds to the ribosome, while collision-specific interactions occur with ribosomal RNA expansion segments. Moreover, a region called the RIM within ZAK interacts with RACK1 on the ribosome, triggering ZAK activation upon collision.
This detailed understanding of ZAK’s mechanics has significant implications for drug development. Kinase proteins, like ZAK, are frequent targets for drugs, but current medications often bind to areas that cause unwanted side effects. “Now, we know more about the makeup of these specialized sites in the ZAK protein and can be more specific in developing drugs that target it,” explained Dr.Green.
The research team plans to continue their work by capturing the complete structure of ZAK and investigating its function when not engaged with colliding ribosomes. This ongoing research promises to further illuminate the intricacies of cellular stress response and pave the way for more effective and targeted therapies.
Funding for this research was provided by:
* Howard Hughes Medical Institute
* European research Council
* National Key R&D program of China
* National Natural Science Foundation of china
* National Institutes of Health (5T32GM007445, F30 CA260910, 5T32AR074920)
* National Science Foundation
* Damon Runyon Cancer Research Foundation
* The Johns Hopkins University Provost’s Postdoctoral Fellowship Program
* Dermatology Foundation’s dermatologist Investigator Research Fellowship.
DOI: 10.1038/s41586-025-09772-8
