A two-component molecular motor positioning vesicles proximal to endosomal membranes. Credit: MPI-CBG
Cells possess an impressive ability to arrange their interiors using small protein machines called molecular motors, which create directed movement. The majority of molecular motors depend on a common kind of chemical energy, ATP, to function. Recently, a group of scientists from the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), the Cluster of Excellence Physics of Life (PoL), the Biotechnology Center (BIOTEC) of TU Dresden, and the National Centre for Biological Sciences (NCBS) in India revealed an unique molecular system that utilizes an alternative energy source and features a new mechanism for performing mechanical jobs.
This molecular motor, which operates likewise to a traditional Stirling engine through repeated contraction and growth, assists in distributing freight to membrane-bound organelles. It is the very first motor utilizing 2 parts, 2 in a different way sized proteins, Rab5 and EEA1, and is driven by GTP instead of ATP. The findings were recently released in the journal Nature Physics.
Motor proteins are remarkable molecular makers within a cell that converts chemical energy, kept in a particle called ATP, into mechanical work. One example is a molecular motor composed of two proteins, EEA1 and Rab5.
In 2016, an interdisciplinary group of cell biologists and biophysicists in the groups of MPI-CBG directors Marino Zerial and Stephan Grill and their colleagues, consisting of PoL and BIOTEC research study group leader Marcus Jahnel, found that the little GTPase protein Rab5 could trigger a contraction in EEA1. These string-shaped tether proteins can acknowledge the Rab5 protein present in a vesicle membrane and bind to it.
The binding of the much smaller sized Rab5 sends a message along the extended structure of EEA1, therefore increasing its versatility, comparable to how cooking softens spaghetti. Such versatility change produces a force that pulls the blister towards the target membrane, where docking and fusion happen. Nevertheless, the team likewise assumed that EEA1 could switch in between a versatile and a stiff state, similar to a mechanical motor movement, merely by communicating with Rab5 alone.
This is where the present research sets in, taking shape through the doctoral work of the two first authors of the research study. Joan Antoni Soler from Marino Zerials research group at MPI-CBG and Anupam Singh from the group of Shashi Thutupalli, a biophysicist at the Simons Centre for the Study of Living Machines at the NCBS in Bangalore, set out to experimentally observe this motor in action.
With a speculative design to investigate the dynamics of the EEA1 protein in mind, Anupam Singh invested 3 months at the MPI-CBG in 2019. “When I met Joan, I explained to him the concept of determining the protein dynamics of EEA1. These experiments required particular adjustments to the protein that enabled measurement of its flexibility based on its structural modifications,” says Anupam.
Joan Antoni Solers expertise in protein biochemistry was an ideal fit for this challenging job. “I was pleased to discover that the method to characterize the EEA1 protein might address whether EEA1 and Rab5 form a two-component motor, as previously presumed. I realized that the difficulties in acquiring the correct particles could be solved by modifying the EEA1 protein to permit fluorophores to attach to specific protein regions. This adjustment would make it much easier to characterize the protein structure and the modifications that can take place when it connects with Rab5,” describes Joan Antoni.
Equipped with the suitable protein particles and the valuable assistance of co-author Janelle Lauer, a senior postdoctoral scientist in Marino Zerials research study group, Joan and Anupam were able to define the dynamics of EEA1 completely utilizing the advanced laser scanning microscopes offered by the light microscopy centers at the MPI-CBG and the NCBS. Noticeably, they found that the EEA1 protein could go through several versatility shift cycles, from stiff to versatile and back again, driven solely by the chemical energy released by its interaction with the GTPase Rab5. These experiments showed that EEA1 and Rab5 form a GTP-driven two-component motor.
To analyze the outcomes, Marcus Jahnel, one of the matching authors and research group leader at PoL and BIOTEC, established a brand-new physical design to explain the coupling between chemical and mechanical actions in the motor cycle. Together with Stephan Grill and Shashi Thutupalli, the biophysicists were also able to compute the thermodynamic performance of the new motor system, which is comparable to that of traditional ATP-driven motor proteins.
” Our outcomes reveal that the proteins EEA1 and Rab5 collaborate as a two-component molecular motor system that can transfer chemical energy into mechanical work. As an outcome, they can play active mechanical roles in membrane trafficking. It is possible that the force-generating molecular motor mechanism might be saved throughout other particles and utilized by several other cellular compartments,” Marino Zerial summarizes the research study.
Marcus Jahnel includes: “I am pleased that we might finally evaluate the idea of an EEA1-Rab5 motor. Its fantastic to see it validated by these brand-new experiments. Many molecular motors utilize a common kind of cellular fuel called ATP. Little GTPases consume another type of fuel, GTP, and have actually been thought about primarily as signaling molecules. That they can also drive a molecular system to create forces and move things around puts these abundant particles in a fascinating brand-new light.”
Stephan Grill is equally excited: “Its a new class of molecular motors! This one does not move like the kinesin motor that transfers freight along microtubules but carries out work while remaining in location. Its a bit like the tentacles of an octopus.”
” The model we utilized is inspired by that of the classical Stirling engine cycle. While the traditional Stirling engine produces mechanical work by broadening and compressing gas, the two-component motor described uses proteins as the working substrate, with protein versatility changes resulting in force generation. As an outcome, this kind of system opens up new possibilities for the advancement of artificial protein engines,” includes Shashi Thutupalli.
In general, the authors hope that this new interdisciplinary study might open brand-new research opportunities in both molecular cell biology and biophysics.
Referral: “Two-component molecular motor driven by a GTPase cycle” by Anupam Singh, Joan Antoni Soler, Janelle Lauer, Stephan W. Grill, Marcus Jahnel, Marino Zerial and Shashi Thutupalli, 4 May 2023, Nature Physics.DOI: 10.1038/ s41567-023-02009-3.
” Our results show that the proteins EEA1 and Rab5 work together as a two-component molecular motor system that can transfer chemical energy into mechanical work. While the standard Stirling engine generates mechanical work by expanding and compressing gas, the two-component motor described usages proteins as the working substrate, with protein versatility modifications resulting in force generation.
Cells possess a remarkable ability to organize their interiors utilizing small protein machines understood as molecular motors, which generate directed movement. Motor proteins are amazing molecular machines within a cell that converts chemical energy, saved in a molecule called ATP, into mechanical work. One example is a molecular motor made up of 2 proteins, EEA1 and Rab5.
