title: Perturbation of apoptosis upon binding of tRNA to the heme domain of cytochrome c.
abstract: In response to apoptotic stimuli, cytochrome c, an inter-membrane space protein is released from mitochondria to activate the cascade of caspases that leads to apoptosis. Recent evidence suggests that cytochrome c interacts with tRNA in the cytoplasm and this interaction was shown to inhibit the caspase mediated apoptotic process. Interestingly, cytochrome c does not contain any putative RNA binding domain. In this report, we sought to define the structural component of cytochrome c that is involved in binding of tRNA. By using gel mobility shift assays, we show that holocytochrome c can interact with tRNA but not apocytochrome c that lacks the heme domain suggesting that heme is essential for the interaction of cytochrome c to tRNA. In addition, using in vitro cross linking and circular dichroism spectroscopic studies, we show that cytochrome c can undergo heme mediated oligomerization. Prevention of heme mediated oligomerization of cytochrome c by potassium ferricyanide treatment prevents the binding of tRNA and promotes caspase activation. Our studies provide a novel regulation of apoptosis by heme dependent tRNA interaction to cytochrome c.
authors.affiliation: Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, AP, India.
authors.forename: Madhavi
authors.initials: M
authors.lastname: Gorla
authors.forename: Naresh Babu V
authors.initials: NB
authors.lastname: Sepuri
mesh_terms: D000818:Animals; D017209:Apoptosis; D020169:Caspases / Q000378:metabolism; D002417:Cattle; D045304:Cytochromes c / Q000737:chemistry* / Q000378:metabolism*; D057809:HEK293 Cells; D006418:Heme / Q000378:metabolism*; D006801:Humans; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism*
chemical_list: D006418:Heme; D045304:Cytochromes c; D012343:RNA, Transfer; D020169:Caspases