TY  - JOUR
A1  - Hofacker, Matthias
A1  - Gompf, Simone
A1  - Zutz, Ariane
A1  - Presenti, Chiara
A1  - Haase, Winfried
A1  - Does, Chris van der
A1  - Model, Kirstin
A1  - Tampé, Robert
T1  - Structural and functional fingerprint of the mitochondrial ATP-binding cassette transporter Mdl1 from Saccharomyces cerevisiae
T2  - Journal of biological chemistry
N2  - The ATP-binding cassette half-transporter Mdl1 from Saccharomyces cerevisiae has been proposed to be involved in the quality control of misassembled respiratory chain complexes by exporting degradation products generated by the m-AAA proteases from the matrix. Direct functional or structural data of the transport complex are, however, not known so far. After screening expression in various hosts, Mdl1 was overexpressed 100-fold to 1% of total mitochondrial membrane protein in S. cerevisiae. Based on detergent screens, Mdl1 was solubilized and purified to homogeneity. Mdl1 showed a high binding affinity for MgATP (Kd = 0.26 μm) and an ATPase activity with a Km of 0.86 mm (Hill coefficient of 0.98) and a turnover rate of 2.6 ATP/s. Mutagenesis of the conserved glutamate downstream of the Walker B motif (E599Q) or the conserved histidine of the H-loop (H631A) abolished ATP hydrolysis, whereas ATP binding was not affected. Mdl1 reconstituted into liposomes showed an ATPase activity similar to the solubilized complex. By single particle electron microscopy, a first three-dimensional structure of the mitochondrial ATP-binding cassette transporter was derived at 2.3-nm resolution, revealing a homodimeric complex in an open conformation.
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/76307
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-763074
SN  - 0021-9258
VL  - 282
IS  - 6
SP  - 3951
EP  - 3961
PB  - American Society for Biochemistry and Molecular Biology Publications
CY  - Bethesda, Md
ER  -