MGME1 processes flaps into ligatable nicks in concert with DNA polymerase gamma during mtDNA replication
Artikel i vetenskaplig tidskrift, 2016

Recently, MGME1 was identified as a mitochondrial DNA nuclease with preference for single-stranded DNA (ssDNA) substrates. Loss-of-function mutations in patients lead to mitochondrial disease with DNA depletion, deletions, duplications and rearrangements. Here, we assess the biochemical role of MGME1 in the processing of flap intermediates during mitochondrial DNA replication using reconstituted systems. We show that MGME1 can cleave flaps to enable efficient ligation of newly replicated DNA strands in combination with POL gamma. MGME1 generates a pool of imprecisely cut products (short flaps, nicks and gaps) that are converted to ligatable nicks by POL gamma through extension or excision of the 3'-end strand. This is dependent on the 3'-5' exonuclease activity of POL gamma which limits strand displacement activity and enables POL gamma to back up to the nick by 3'-5' degradation. We also demonstrate that POL gamma-driven strand displacement is sufficient to generate DNA- but not RNA-flap substrates suitable for MGME1 cleavage and ligation during replication. Our findings have implications for RNA primer removal models, the 5'-end processing of nascent DNA at OriH, and DNA repair.

exonuclease

disease

transfer-rna synthetases

ligase

mice

excision-repair

iii

Biochemistry & Molecular Biology

accessory subunit

endonuclease

okazaki fragment maturation

human mitochondrial-dna

base

Författare

Jay Uhler

Göteborgs universitet

Christian Thörn

Göteborgs universitet

Thomas J. Nicholls

Göteborgs universitet

S. Matic

D. Milenkovic

Claes M Gustafsson

Göteborgs universitet

Maria Falkenberg

Göteborgs universitet

Nucleic Acids Research

0305-1048 (ISSN) 1362-4962 (eISSN)

Vol. 44 12 5861-5871

Ämneskategorier

Klinisk medicin

DOI

10.1093/nar/gkw468

Mer information

Skapat

2017-10-10