Table 1.

Biological importance and biochemical functions of editosome proteins – alternative nomenclatures are also mentioned (e.g. TbMP63, T. brucei mitochondrial protein of 63 kDa).

Protein	Proposed function	Essentiality	Technique used for inhibition	Effects on RNA editing activities and the editosome complex	References
KREPA1/TbMP81	RNA/protein interaction	BF and PF	RNAi-mediated repression	-Inhibition of in vivo RNA editing -Loss of endoribonuclease, TUTase and RNA ligase activities associated with insertion editing	Drozdz et al. (2002) O’Hearn et al. (2003)
KREPA2/TbMP63	RNA/protein interaction	PF	RNAi-mediated repression	-Great reduction in endonuclease activity for both U deletion and U insertion -Loss of KREL1 -Disruption of proper editosome assembly	Huang et al. (2002)
KREPA3/TbMP42	RNA/protein interaction	BF and PF	Regulatable knockout in BF RNAi-mediated repression in PF	-Complete loss of editosome in BF -Reduced RNA editing activity in PF -Inhibition of endoribonucleolytic cleavage in both U deletion and U insertion, but other steps not affected	Brecht et al. (2005), Law et al. (2008), Guo et al. (2008), Guo et al. (2010)
KREPA4/TbMP24	RNA/protein interaction	PF	RNAi-mediated repression	-Loss of editosome proteins -Reduction of both U deletion and U insertion -Reduction of editosome stability and/or interruption of editosome assembly	Kala and Salavati (2010), Salavati et al. (2006)
KREPA5/TbMP19	RNA/protein interaction	N.D.	N.D.		Carnes et al. (2011), Panigrahi et al. (2006)
KREPA6/TbMP18	RNA/protein interaction	PF	RNAi-mediated repression	-Loss of both U deletion and U insertion -Loss of the structural integrity of editosome	Tarun et al. (2008)
KREN1/TbMP90	U deletion-specific endonuclease	BF and PF	RNAi-mediated repression in PF Regulatable knockout in BF	-Inhibition of in vivo editing -Inhibition of in vitro endoribonucleolytic cleavage of deletion substrates; cleavage of insertion substrates and other catalytic activities of editing not affected	Kang et al. (2006), Trotter et al. (2005)
KREN3/TbMP67	Endonuclease specific for Cytochrome oxidase II pre-edited mRNA	BF	Regulatable knockout	-Elimination of COII RNA editing in vivo -Inhibition of endonucleolytic cleavage of COII RNA substrate in vitro -Editosomes and in vitro catalytic activities (based on A6 derived RNA substrates) retained	Carnes et al. (2008)
KREN2/TbMP61	Insertion-specific endonuclease activity	BF and PF	RNAi-mediated repression in PF Regulatable knockout in BF	-Inhibition of in vivo editing in PF and BF -Inhibition of in vitro cleavage of insertion editing substrates; cleavage of deletion substrates and other catalytic activities of editing not affected	Carnes et al. (2005)
KREPB4/TbMP46	RNA/protein interaction	PF	RNAi-mediated repression	-Altered editosome integrity and abundance -Reduced in vivo RNA editing -Reduced insertion and deletion endonuclease activities	Babbarwal et al. (2007)
KREPB5/TbMP44	RNA/protein interaction	BF	Regulatable knockout	-Loss of editing in vivo -Loss of editing-associated catalytic activities in vitro -Perturbation of the editosome structure	Baldassarre et al. (2003)
KREPB6/TbMP49	RNA/protein interaction	N.D.	N.D.		Panigrahi et al. (2006), Carnes et al. (2011)
KREPB7/TbMP47	RNA/protein interaction	N.D.	N.D.		Panigrahi et al. (2006), Carnes et al. (2011)
KREPB8/TbMP41	RNA/protein interaction	N.D.	N.D.		Panigrahi et al. (2006), Carnes et al. (2011)
KREL1/TbMP52	Deletion-specific Ligase	BF	Regulatable knockout	-Complete inhibition of RNA editing	Schnaufer et al. (2001), Cruz-Reyes et al. (2002)
KREL2/TbMP48	Insertion-specific Ligase	Not essential in BF and PF	RNAi-mediated repression	-No effect on RNA editing	Drozdz et al. (2002), Gao and Simpson (2003), Cruz-Reyes et al. (2002)
KREX1/TbMP100	3′–5′ exonuclease responsible for U-deletion	PF	RNAi-mediated repression	-Disruption of editosome -Reduction of KREN1 in editosomes -Preferential Inhibition of -In vitro pre-cleaved U-deletion editing	Kang et al. (2005), Rogers et al. (2007), Ernst et al. (2009)
KREX2/TbMP99	3′–5′ exonuclease activity	PF (Minor effect on cell growth)	RNAi-mediated repression	-Little effect on editosome stability -Reductions of KREPA2 and KREL1 in editosomes -Modest reductions of both insertion and deletion endonuclease activities -Significant reduction of U removal in vitro	Rogers et al. (2007), Ernst et al. (2009)
KRET1	Guide RNA-specific TUTase	PF	RNAi-mediated repression	-Reduction of RNA editing -Accumulation of guide RNA with shorter U tails	Aphasizhev et al. (2002), Ernst et al. (2003)
KRET2/TbMP57	U insertion-specific TUTase	PF	RNAi-mediated repression	-Complete inhibition of U-insertion in vitro -No effect on the length of guide RNA oligo(U) tails	Aphasizhev et al. (2003c), Ernst et al. (2003)
KREH1/mHel61p	Helicase activity	PF	Knockout	-Reduced amounts of edited mRNAs	Missel et al. (1997), Li et al. (2011)

N.D.: not determined.