Protein import and genome replication are essential processes for mitochondrial biogenesis and propagation. The J-domain proteins Pam16 and Pam18 regulate the presequence translocase of the mitochondrial inner membrane. In the protozoan Trypanosoma brucei, their counterparts are TbPam16 and TbPam18, which are essential for the procyclic form (PCF) of the parasite, though not involved in mitochondrial protein import. Here, we show that during evolution, the 2 proteins have been repurposed to regulate the replication of maxicircles within the intricate kDNA network, the most complex mitochondrial genome known. TbPam18 and TbPam16 have inactive J-domains suggesting a function independent of heat shock proteins. However, their single transmembrane domain is essential for function. Pulldown of TbPam16 identifies a putative client protein, termed MaRF11, the depletion of which causes the selective loss of maxicircles, akin to the effects observed for TbPam18 and TbPam16. Moreover, depletion of the mitochondrial proteasome results in increased levels of MaRF11. Thus, we have discovered a protein complex comprising TbPam18, TbPam16, and MaRF11, that controls maxicircle replication. We propose a working model in which the matrix protein MaRF11 functions downstream of the 2 integral inner membrane proteins TbPam18 and TbPam16. Moreover, we suggest that the levels of MaRF11 are controlled by the mitochondrial proteasome.

• MeSH
• mitochondriální DNA * genetika   metabolismus   MeSH
• mitochondriální proteiny metabolismus   genetika   MeSH
• mitochondrie metabolismus   genetika   MeSH
• molekulární evoluce MeSH
• protozoální proteiny * metabolismus   genetika   MeSH
• replikace DNA * MeSH
• Trypanosoma brucei brucei * metabolismus   genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• mitochondriální DNA * MeSH
• mitochondriální proteiny MeSH
• protozoální proteiny * MeSH

The kinetoplast (k), the uniquely packaged mitochondrial DNA of trypanosomatid protists is formed by a catenated network of minicircles and maxicircles that divide and segregate once each cell cycle. Although many proteins involved in kDNA replication and segregation are now known, several key steps in the replication mechanism remain uncharacterized at the molecular level, one of which is the nabelschnur or umbilicus, a prominent structure which in the mammalian parasite Trypanosoma brucei connects the daughter kDNA networks prior to their segregation. Here we characterize an M17 family leucyl aminopeptidase metalloprotease, termed TbLAP1, which specifically localizes to the kDNA disk and the nabelschur and represents the first described protein found in this structure. We show that TbLAP1 is required for correct segregation of kDNA, with knockdown resulting in delayed cytokinesis and ectopic expression leading to kDNA loss and decreased cell proliferation. We propose that TbLAP1 is required for efficient kDNA division and specifically participates in the separation of daughter kDNA networks.

• MeSH
• buněčný cyklus fyziologie   MeSH
• kinetoplastová DNA genetika   MeSH
• leucylaminopeptidasa genetika   metabolismus   MeSH
• mitochondriální DNA genetika   MeSH
• mitochondrie metabolismus   ultrastruktura   MeSH
• protozoální DNA genetika   MeSH
• protozoální proteiny metabolismus   MeSH
• replikace DNA fyziologie   MeSH
• Trypanosoma brucei brucei genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kinetoplastová DNA MeSH
• leucylaminopeptidasa MeSH
• mitochondriální DNA MeSH
• protozoální DNA MeSH
• protozoální proteiny MeSH

Kinetoplastids are flagellated protozoans, whose members include the pathogens Trypanosoma brucei, T. cruzi and Leishmania species, that are considered among the earliest diverging eukaryotes with a mitochondrion. This organelle has become famous because of its many unusual properties, which are unique to the order Kinetoplastida, including an extensive kinetoplast DNA network and U-insertion/deletion type RNA editing of its mitochondrial transcripts. In the last decade, considerable progress has been made in elucidating the complex machinery of RNA editing. Moreover, our understanding of the structure and replication of kinetoplast DNA has also dramatically improved. Much less however, is known, about the developmental regulation of RNA editing, its integration with other RNA maturation processes, stability of mitochondrial mRNAs, or evolution of the editing process itself. Yet the profusion of genomic data recently made available by sequencing consortia, in combination with methods of reverse genetics, hold promise in understanding the complexity of this exciting organelle, knowledge of which may enable us to fight these often medically important protozoans.

• MeSH
• editace RNA MeSH
• exprese genu MeSH
• genetická transkripce MeSH
• genom protozoální * MeSH
• Kinetoplastida genetika   MeSH
• kinetoplastová DNA chemie   MeSH
• messenger RNA metabolismus   MeSH
• mitochondriální geny * MeSH
• mitochondrie genetika   MeSH
• RNA protozoální metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• kinetoplastová DNA MeSH
• messenger RNA MeSH
• RNA protozoální MeSH

• MeSH
• biologická evoluce MeSH
• Crithidia fasciculata genetika   ultrastruktura   MeSH
• elektronová mikroskopie MeSH
• fylogeneze MeSH
• Kinetoplastida genetika   ultrastruktura   MeSH
• kinetoplastová DNA genetika   ultrastruktura   MeSH
• Trypanosoma genetika   ultrastruktura   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Research Support, U.S. Gov't, P.H.S. MeSH
• Názvy látek
• kinetoplastová DNA MeSH