Characterization of anti-silencing factor 1 in Leishmania major

Abstract

Key words: Leishmania major -anti-silencing factor 1 -histone chaperone Leishmania spp is a member of the Trypanosomatidae family and a parasitic protozoa and digenetic eukaryote of medical and veterinary relevance. Leishmania undergoes several changes to adapt to and survive in different hostile environments, namely the insect vector digestive tract and the vertebrate host's macrophagic phagolysosomes. For that a tight and agile control of gene expression is required.Differently from most of the eukaryotes, these parasites have polycistronic transcription and control of gene expression occurs primarily at the posttranscriptional level (reviewed by Clayton 2002, Martinez-Calvillo et al. 2010. Likewise other eukaryotes, in these parasites the chromatin structure modulates the access of proteins to the DNA, which ultimately regulates different aspects of gene expression, DNA processing, replication and double-stranded DNA repair (Navarro et al. 1999, Elias et al. 2001, Gontijo et al. 2003, McNairn & Gilbert 2003.Anti-silencing factor 1 (ASF1) is a histone chaperone that together with chromatin assembly factor (CAF)-1 adds histones H3 and H4 onto newly replicated DNA (Tyler et al. 2001). This suggests a role for ASF1 in chro- matin assembly regulation (Loyola & Almouzni 2004, Zhang et al. 2005. ASF1 can be involved either in gene activation or transcriptional repression; it depends on the factors it interacts with (Sutton et al. 2001, Schwabish & Struhl 2006, Adkins et al. 2007, Takahata et al. 2009, Varv et al. 2010. In different eukaryotes deletion of ASF1 alters response to DNA damage and DNA replication blocking agents (Le et al. 1997, Tyler et al. 1999) and leads to gross chromosomal rearrangements (Prado et al. 2004) and even to cell death (Sanematsu et al. 2006).The increased susceptibility of chromatin-assembly factor mutants to DNA-damaging agents may be an effect of the direct role of these factors in modulating chromatin structure (Mello et al. 2002). In addition, an association between ASF1 and genomic stability has been provided by the identification of a dynamic interaction between ASF1 and the Rad53 DNA damage checkpoint protein. Also, activation of ASF1 may be an important cellular response to DNA damage and replication stress (Emili et al. 2001, Hu et al. 2001. When DNA damage occurs, ASF1 is recruited to the lesion site where it may disrupt the H3/H4 tetramer. This results in nucleosome eviction and allows access of the repair machinery to unencumbered DNA (Canfield et al. 2009).In Leishmania species ASF1 roles have not been investigated, although orthologous genes have been annotated in the sequenced genomes (tritrypdb.org). In another trypanosomatid, Trypanosoma brucei, the participation of ASF1 in the machinery that regulates spindle assembly and S-phase progression has been described (Li et al. 2007). Therefore, given that ASF1 is associated with gene expression in other eukaryotes and that chromatin modifications are relevant for controlling ASF1 from L. major • Ricardo Scher et al. 37...

Identification of Differentially Expressed Proteins from Leishmania amazonensis Associated with the Loss of Virulence of the Parasites

“…Data are showed in Table 3 [53]–[70]. In relation to known proteins, the majority are commonly involved in the parasites' metabolism, such as nucleosome assembly proteins [57], 6-phosphogluconolactonase [62], and rieske iron sulfur proteins [66], while others, such as mannose-1-phosphate guanyltransferase [56] and short chain dehydrogenase [65], have been employed as candidates for immunotherapeutic targets.…”

“…a ) Spots match ID number obtained from ImageMaster Platinum;b ) Name of the identified protein;c ) Uniprot identification code;d ) Experimentally predicted and expected isoelectric point ( pI );e ) Experimentally predicted and expected molecular weight ( Mr , in kDa);f ) Number of identified peptides by MS;g ) Percentage of the protein sequence covered by identified peptides;h ) Normalized data from R0 represented by mean values of each condition divided by R30 value;i ) Fold represents the maximum spot intensity mean value of the conditions divided by the smallest value;j) One-way ANOVA ( P <0.01) obtained from spot analysis;k ) Biological functions according to NCBI, UniProt, and Gene Ontology databases;l ) Biological activity and/or immunological application described in other studies: [53] Joshi et al, 1996; [54] Tielens et al, 2010; [55] Soto et al, 1996; [56] Lackovic et al, 2010; [57] Scher et al, 2012; [58] Sánchez-Cañete et al, 2009; [59] Peris et al, 1994; [60] Steiner et al, 2007; [61] Jaramillo et al, 2011; [62] Duclert-Savatier et al, 2009; [63] Celeste et al, 2004; [64] Liu et al, 2011; [65] Leblanc et al, 1998; [66] Priest et al, 1996; [67] Bakker-Grunwald, 1992; [68] Banerjee et al, 2006; [69] Casanova et al, 2008; [70] Jensen et al, 2001. The proteins were identified through the data included in the NCBI database (dated June 2012) for Leishmania spp.…”

“…l ) Biological activity and/or immunological application described in other studies: [53] Joshi et al, 1996; [54] Tielens et al, 2010; [55] Soto et al, 1996; [56] Lackovic et al, 2010; [57] Scher et al, 2012; [58] Sánchez-Cañete et al, 2009; [59] Peris et al, 1994; [60] Steiner et al, 2007; [61] Jaramillo et al, 2011; [62] Duclert-Savatier et al, 2009; [63] Celeste et al, 2004; [64] Liu et al, 2011; [65] Leblanc et al, 1998; [66] Priest et al, 1996; [67] Bakker-Grunwald, 1992; [68] Banerjee et al, 2006; [69] Casanova et al, 2008; [70] Jensen et al, 2001. The proteins were identified through the data included in the NCBI database (dated June 2012) for Leishmania spp.…”

Characterization of two different Asf1 histone chaperones with distinct cellular localizations and functions in Trypanosoma brucei

“…The nature of DNA damage checkpoints are largely unknown in trypanosomes (67) , which do not possess homologs of the Rad53 kinase, an enzyme that mediates replication arrest in many organism (68). Similarly, we observed that overexpression of an Asf1A homolog caused an increased sensitivity to genotoxic agents by affecting chromatin remodeling during DNA repair in Leishmania major (69). …”

Caracterização molecular do envolvimento das proteínas LmHus1 e LmRad9 em mecanismos de reconhecimento e reparo de DNA no parasito Leishmania major

“…Isto sugere que o complexo de 9-1-1 atua como guardião da estabilidade genômica em eucariotos não somente como um sensor de danos no DNA, mas também como componente da maquinaria de síntese de DNA durante o reparo das lesões e também como regulador do funcionamento e proteção das extremidades cromossômicas. (Nardelli, da Cunha et al 2009, Glover and Horn 2012, Scher, Garcia et al 2012.…”