TY - JOUR
T1 - In Vivo Dissection of the Intrinsically Disordered Receptor Domain of Tim23
AU - Günsel, Umut
AU - Paz, Eyal
AU - Gupta, Ruhita
AU - Mathes, Isabella
AU - Azem, Abdussalam
AU - Mokranjac, Dejana
N1 - Publisher Copyright:
© 2020 The Author(s)
PY - 2020/5/1
Y1 - 2020/5/1
N2 - In the intermembrane space (IMS) of mitochondria, the receptor domain of Tim23 has an essential role during translocation of hundreds of different proteins from the cytosol via the TOM and TIM23 complexes in the outer and inner membranes, respectively. This intrinsically disordered domain, which can even extend into the cytosol, was shown, mostly in vitro, to interact with several subunits of the TOM and TIM23 complexes. To obtain molecular understanding of this organizational hub in the IMS, we dissected the IMS domain of Tim23 in vivo. We show that the interaction surface of Tim23 with Tim50 is larger than previously thought and reveal an unexpected interaction of Tim23 with Pam17 in the IMS, impairment of which influences their interaction in the matrix. Furthermore, mutations of two conserved negatively charged residues of Tim23, close to the inner membrane, prevented dimerization of Tim23. The same mutations increased exposure of Tim23 on the mitochondrial surface, whereas dissipation of membrane potential decreased it. Our results reveal an intricate network of Tim23 interactions in the IMS, whose influence is transduced across two mitochondrial membranes, ensuring efficient translocation of proteins into mitochondria.
AB - In the intermembrane space (IMS) of mitochondria, the receptor domain of Tim23 has an essential role during translocation of hundreds of different proteins from the cytosol via the TOM and TIM23 complexes in the outer and inner membranes, respectively. This intrinsically disordered domain, which can even extend into the cytosol, was shown, mostly in vitro, to interact with several subunits of the TOM and TIM23 complexes. To obtain molecular understanding of this organizational hub in the IMS, we dissected the IMS domain of Tim23 in vivo. We show that the interaction surface of Tim23 with Tim50 is larger than previously thought and reveal an unexpected interaction of Tim23 with Pam17 in the IMS, impairment of which influences their interaction in the matrix. Furthermore, mutations of two conserved negatively charged residues of Tim23, close to the inner membrane, prevented dimerization of Tim23. The same mutations increased exposure of Tim23 on the mitochondrial surface, whereas dissipation of membrane potential decreased it. Our results reveal an intricate network of Tim23 interactions in the IMS, whose influence is transduced across two mitochondrial membranes, ensuring efficient translocation of proteins into mitochondria.
KW - TIM23 complex
KW - mitochondria
KW - presequence pathway
KW - protein sorting
KW - protein translocation
UR - http://www.scopus.com/inward/record.url?scp=85083512197&partnerID=8YFLogxK
U2 - 10.1016/j.jmb.2020.03.031
DO - 10.1016/j.jmb.2020.03.031
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C2 - 32277989
AN - SCOPUS:85083512197
SN - 0022-2836
VL - 432
SP - 3326
EP - 3337
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 10
ER -