Implications of Membrane Binding by the Fe-S Cluster-Containing N-Terminal Domain in the Drosophila Mitochondrial Replicative DNA Helicase

Minyoung So; Johnny Stiban; Grzegorz L Ciesielski; Stacy L Hovde; Laurie S Kaguni

doi:10.3389/fgene.2021.790521

Implications of Membrane Binding by the Fe-S Cluster-Containing N-Terminal Domain in the Drosophila Mitochondrial Replicative DNA Helicase

Front Genet. 2021 Dec 7:12:790521. doi: 10.3389/fgene.2021.790521. eCollection 2021.

Authors

Minyoung So¹, Johnny Stiban^{1

2}, Grzegorz L Ciesielski^{1

3

4}, Stacy L Hovde¹, Laurie S Kaguni^{1

3}

Affiliations

¹ Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI, United States.
² Department of Biology and Biochemistry, Birzeit University, Birzeit, Palestine.
³ Institute of Biosciences and Medical Technology, University of Tampere, Tampere, Finland.
⁴ Department of Chemistry, Auburn University at Montgomery, Montgomery, AL, United States.

Abstract

Recent evidence suggests that iron-sulfur clusters (ISCs) in DNA replicative proteins sense DNA-mediated charge transfer to modulate nuclear DNA replication. In the mitochondrial DNA replisome, only the replicative DNA helicase (mtDNA helicase) from Drosophila melanogaster (Dm) has been shown to contain an ISC in its N-terminal, primase-like domain (NTD). In this report, we confirm the presence of the ISC and demonstrate the importance of a metal cofactor in the structural stability of the Dm mtDNA helicase. Further, we show that the NTD also serves a role in membrane binding. We demonstrate that the NTD binds to asolectin liposomes, which mimic phospholipid membranes, through electrostatic interactions. Notably, membrane binding is more specific with increasing cardiolipin content, which is characteristically high in the mitochondrial inner membrane (MIM). We suggest that the N-terminal domain of the mtDNA helicase interacts with the MIM to recruit mtDNA and initiate mtDNA replication. Furthermore, Dm NUBPL, the known ISC donor for respiratory complex I and a putative donor for Dm mtDNA helicase, was identified as a peripheral membrane protein that is likely to execute membrane-mediated ISC delivery to its target proteins.

Keywords: NUBPL/Ind1; genome stability; iron-sulfur clusters; liposomes; membrane binding; mitochondria; replicative helicase.