RNA editing and mitochondrial activity in promastigotes and amastigotes of Leishmania donovani

Abstract

Kinetoplast maxicircle DNA sequence organization was investigated in Leishmania donovani, strain 1S LdBob. Gene arrangement in the coding (conserved) region of the maxicircle is collinear with that of most trypanosomatids, with individual genes showing 80-90% nucleotide identity to Leishmania tarentolae, strain UC. The notable exception was an integration of a full-size minicircle sequence in the ND1 gene coding region found in L. donovani. Editing patterns of the mitochondrial mRNAs investigated also followed L. tarentolae UC patterns, including productive editing of the components of respiratory complexes III, IV and V, and ribosomal protein S12 (RPS12), as well as the lack of productive editing in five out of six pan-edited cryptogenes (ND3, ND8, ND9, G3, G4) found in these species. Several guide RNAs for the editing events were localized in minicircles and maxicircles in the locations that are conserved between the species. Mitochondrial activity, including rates of oxygen consumption, the presence and the levels of respiratory complexes and their individual subunits and the steady-state levels of several mitochondrial-encoded mRNAs were essentially the same in axenically grown amastigotes and in promastigotes of L. donovani. However, some modulation of mitochondrial activity between these developmental stages was suggested by the finding of an amastigote-specific component in Complex IV, a down-regulation of mitochondrial RNA-binding proteins (MRP) [define] and MRP-associated protein (MRP-AP) in amastigotes, and by variations in the levels of RPS12, ND3, ND9, G3 and G4 pre-edited transcripts.

Evidence of RNA editing in Leishmania braziliensis promastigotes

“…However, none of the database entries showed significant homology with the rest of the sequence. An important clue about the nature of this cDNA clone was obtained after searching in the GenBank database: the sequence gave a high score of homology with the FJ416603 entry, which contains a partial sequence of the L. donovani maxicircle (Nebohacova et al 2009). Again, the homology was restricted to the 5′-end of the 600D sequence.…”

“…Dashes denote gaps introduced to maximize alignment. The nucleotides that form part of the initiation and termination codons, which are created by editing, are underlined this cryptogen in L. donovani (Nebohacova et al 2009) and L. amazonensis (Maslov 2010), which have been recently determined. Figure 2 shows the alignment of ND8 cryptogenes from these four Leishmania species, evidencing remarkable sequence conservation, which suggests both a selective pressure to maintain the DNA sequence and, probably, a functional importance for these cryptogenes.…”

“…Apparently, in cultured trypanosomes, the NADH dehydrogenase complex is not functional and not used for energy production (Benne 1994). Disruption of RNA editing by prolonged cell culture has been documented in L. tarentolae (Thiemann et al 1994) and L. donovani (Nebohacova et al 2009). In L. tarentolae, species in which this phenomenon has been studied more extensively, transcripts of the G1-G5 cryptogenes are panedited in a recently isolated strain (LEM125), but not in the UC strain which has been axenically cultured for many years.…”

“…Ibrahim and co-workers (Ibrahim et al 2008) described that L. donovani coxII gene is edited in an identical manner as the homologous gene in L. tarentolae. Recently, a more complete picture of the RNA editing process in this species has been reported (Nebohacova et al 2009). In L. major, after analysis of the maxicircle sequence and its comparison with the L. tarentolae maxicircle sequence, it has been suggested that the RNA editing process should be equivalent to that described in L. tarentolae (Yatawara et al 2008).…”

Expresión diferencial entre estadios de Trypanosoma cruzi I en el aislamiento de un paciente con cardiomiopatía chagásica crónica de zona endémica de Santander, Colombia

“…En este estudio, la subunidad IV de la enzima citocromooxidasa C presentó una mayor expresión en el estadio de amastigote (figura 3D), lo que está de acuerdo con este resultado; los datos preliminares indican que en T. brucei esta subunidad tiene poca expresión en los tripomastigotes (43). Esta subunidad cataliza la transferencia de electrones de citocromo C reducido a oxígeno (44).…”