TY - JOUR
T1 - Dynamics of protein-protein interactions at the mscl periplasmic-lipid interface
AU - Zhong, Dalian
AU - Yang, Li Min
AU - Blount, Paul
N1 - Funding Information:
This work was supported by grant I-1420 from the Welch Foundation, grant RP100146 from the Cancer Prevention & Research Institute of Texas, and grant R01GM061028 from the National Institutes of Health.
PY - 2014/1/21
Y1 - 2014/1/21
N2 - MscL, the highly conserved bacterial mechanosensitive channel of large conductance, is one of the best studied mechanosensors. It is a homopentameric channel that serves as a biological emergency release valve that prevents cell lysis from acute osmotic stress. We previously showed that the periplasmic region of the protein, particularly a single residue located at the TM1/periplasmic loop interface, F47 of Staphylococcus aureus and I49 of Escherichia coli MscL, plays a major role in both the open dwell time and mechanosensitivity of the channel. Here, we introduced cysteine mutations at these sites and found they formed disulfide bridges that decreased the channel open dwell time. By scanning a likely interacting domain, we also found that these sites could be disulfide trapped by addition of cysteine mutations in other locations within the periplasmic loop of MscL, and this also led to rapid channel kinetics. Together, the data suggest structural rearrangements and protein-protein interactions that occur within this region upon normal gating, and further suggest that locking portions of the channel into a transition state decreases the stability of the open state.
AB - MscL, the highly conserved bacterial mechanosensitive channel of large conductance, is one of the best studied mechanosensors. It is a homopentameric channel that serves as a biological emergency release valve that prevents cell lysis from acute osmotic stress. We previously showed that the periplasmic region of the protein, particularly a single residue located at the TM1/periplasmic loop interface, F47 of Staphylococcus aureus and I49 of Escherichia coli MscL, plays a major role in both the open dwell time and mechanosensitivity of the channel. Here, we introduced cysteine mutations at these sites and found they formed disulfide bridges that decreased the channel open dwell time. By scanning a likely interacting domain, we also found that these sites could be disulfide trapped by addition of cysteine mutations in other locations within the periplasmic loop of MscL, and this also led to rapid channel kinetics. Together, the data suggest structural rearrangements and protein-protein interactions that occur within this region upon normal gating, and further suggest that locking portions of the channel into a transition state decreases the stability of the open state.
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U2 - 10.1016/j.bpj.2013.12.006
DO - 10.1016/j.bpj.2013.12.006
M3 - Article
C2 - 24461012
AN - SCOPUS:84892777113
SN - 0006-3495
VL - 106
SP - 375
EP - 381
JO - Biophysical journal
JF - Biophysical journal
IS - 2
ER -