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Rhomboids and proteolysis in the Dicty mitochondrion

Rhomboids and proteolysis in the Dicty mitochondrion

Thompson, Elinor (2015) Rhomboids and proteolysis in the Dicty mitochondrion. In: Dicty 2015, 9-13 August 2015, Royal Holloway University London, Egham.

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Abstract

Proteolytic regulation in Dictoystelium mitochondria
Proteolysis is increasingly recognised as a key regulatory mechanism in cell biology, proteases comprising 2-5% of organism genomes across evolution. They govern protein activation, localisation, exposure of cryptic binding sites and release of neoproteins: indeed, altered protease expression and substrate-proteolysis are important in pathogenesis, including Parkinson’s and other neurodegenerative diseases. Proteolysis takes place within cell membranes via families of evolutionarily well-conserved intermembrane proteases. Amongst these are the 'rhomboid' serine proteases, enzymes known to influence development, signalling and infection in a range of eukaryotes and prokaryotes. Of four predicted enzymatically-active rhomboids in D. discoideum, we have found three to be important in the mitochondrion. The conserved eukaryotic, mitochondrial 'PARL'-type protease (RhmD) cannot be inactivated but the rhmA-rhomboid knockout responds poorly to chemoattractant, shows decreased motility and displays aberrant mitochondrial ultrastructure and altered respiration. A further rhomboid knockout, rhmB-, has reduced growth rates and folate chemotaxis and, interestingly, a double A/B-mutant is unable to phagocytose prey bacteria. Whereas RhmA-GFP is visualised at the contractile vacuole, RhmB-GFP colocalises with MitoTracker to the mitochondrion, but transcription of A and B both peak during multicellular growth and, in qPCR, rhmB transcription is differentially regulated in rhmA- cells. Since transcription levels are also altered of our predicted Dictyostelium orthologues of Saccharomyces cerevisiae mitochondrial rhomboid-substrates, we are examining (co-)localisation of orthologue-RFP in GFP-expressing and rhmA and B- cells, while conducting reporter studies with the remaining rhomboids C and D.

Item Type: Conference or Conference Paper (Lecture)
Uncontrolled Keywords: Dictyostelium, microbiology, protease, rhomboid
Subjects: Q Science > QR Microbiology
Faculty / Department / Research Group: Faculty of Engineering & Science > Department of Life & Sports Sciences
Last Modified: 26 Apr 2017 09:57
Selected for GREAT 2016: None
Selected for GREAT 2017: GREAT b
Selected for GREAT 2018: None
URI: http://gala.gre.ac.uk/id/eprint/13989

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