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Function of the INA complex in assembly of the mitochondrial oxidative phosphorylation system

dc.contributor.advisorRehling, Peter Prof. Dr.
dc.contributor.authorNaumenko, Nataliia
dc.titleFunction of the INA complex in assembly of the mitochondrial oxidative phosphorylation systemde
dc.contributor.refereeSchwappach, Blanche Prof. Dr.
dc.description.abstractengThe majority of cellular ATP is produced by the mitochondrial F1Fo-ATP synthase, also called complex V, which consists of nuclear- and mitochondrial-encoded subunits. In order to form a functional enzyme, its proteins must be expressed at appropriate levels, delivered to the correct destination within mitochondria and then properly assembled. Proteins called assembly factors assist in the assembly process and tightly regulate it on various levels. The F1Fo-ATP synthase is thought to assemble in a modular way, involving the formation of distinct assembly intermediates that associate with each other in a de ned order. Importantly, formation of the proton-conducting membrane channel is the last step of complex V biogenesis. The channel-forming Atp6 and Atp9 subunits are retained within two di erent assembly intermediates and their association generates a mature F1Fo-ATP synthase. How this last step of complex V biogenesis is regulated in order to prevent premature proton-channel formation and thus membrane potential dissipation is currently poorly understood. Recently, the Inner Membrane Assembly Complex (INAC) was identi ed that participates in the assembly of yeast F1Fo-ATP synthase. Its two members, Ina22 and Ina17, were shown to physically associate with nuclear-encoded F1Fo-ATP synthase subunits and to facilitate assembly of the peripheral stalk of complex V. In this study, we revise the current knowledge of F1Fo-ATP synthase biogenesis and describe a novel regulatory role of INAC. We found that INAC interacts not only with nuclear-encoded, but also with mitochondrial-encoded structural subunits, as well as other assembly factors of the F1Fo-ATP synthase, within two distinct assembly intermediates. One of these intermediates contains Atp6 and the other one contains the Atp9 ring, that together form a proton-conducting channel. We found that, in contrast to what was known before, all nuclear-encoded subunits associate with the Atp6-containing assembly intermediate prior to their interaction with the Atp9 ring. Therefore, a novel F1Fo-ATP synthase assembly intermediate was characterized in this study. Our extensive analyses revealed that the INA complex is involved in the most critical step of complex V biogenesis, namely formation of the proton-conducting membrane channel. Therefore, INAC ensures the tight coupling of proton movement to ATP production. Moreover, our data provides novel insights into the composition of assembly intermediates of complex V and extends our understanding of its assembly
dc.contributor.coRefereeLuehrmann, Reinhard Prof. Dr.
dc.subject.engATP synthasede
dc.affiliation.instituteGöttinger Graduiertenschule für Neurowissenschaften, Biophysik und molekulare Biowissenschaften (GGNB)de
dc.subject.gokfullBiologie (PPN619462639)de

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