Why the study?
The mechanical stability of titin I27 has been characterized at laboratory temperatures, leaving its behavior at physiological temperature unclear.
The titin I27 domain exhibits unexpectedly low mechanical stability at physiological temperatures, challenging previous consensus based on room temperature experiments.
Titin I27 stability data remain hypothesis-generating; leaves open force-dependent roles in cardiac sarcomere function.
High Resolution Image Download MS PowerPoint Slide The extensively studied immunoglobulin (Ig) domain I27 of the giant force-bearing protein titin has provided a basis for our current understanding of the structural stability, dynamics, and function of the numerous mechanically stretched Ig domains in the force-bearing I-band of titin. The current consensus is that titin I27 has a high mechanical stability characterized by very low unfolding rate (<10 –3 s –1 ) in physiological force range and high unfolding forces (>100 pN) at typical physiological force loading rates from experiments at typical laboratory temperatures. Here, we report that when the temperature is increased from 23 to 37 °C, the unfolding rate of I27 drastically increases by ∼100-fold at the physiological level of forces, indicating a low mechanical stability of I27 at physiological conditions. The result provides new insights into the structural states and the associated functions of I27 and other similar titin I-band Ig domains.
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Yu et al. (2021) studied this question.
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