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. 2009 Apr 14;7(4):e1000084. doi: 10.1371/journal.pbio.1000084

Figure 1. Identification of PfSir2B and Phylogenetic Relationships between PfSir2A and PfSir2B within Apicomplexan Parasites.

Figure 1

(A) PfSir2B is a large gene and encodes a ∼150-kD protein. PfSir2B, like all sirtuins, contains similarity to other Sir2 molecules within the catalytic regions (black). PfSir2B has 29%/43% identity/similarity with Schizosaccharomyces pombe Sir2 (SpSir2) and 26%/51% identity/similarity with the previously identified PfSir2A. PfSir2B most closely resembles a “type IV” sirtuin, which groups together other sirtuins with diverse roles in cellular signalling such as human SIRT6, involved in telomeric chromatin maintenance [82,83] as well as SIRT7, an activator of RNA polymerase I [84]. PfSir2B has with 38%/53% identity/similarity to type IV sirtuins.

(B) Phylogenetic analysis of apicomplexan Sir2 paralogues. Sir2 homologues were identified from the sequencing projects of four Plasmodium species; P. vivax [85], P. chabaudi [86], P. yoelli [86], P. berghei [86], together with Sir2 homologues from other apicomplexan parasites: T. gondii (http://toxodb.org), T. annulata [87], T. parva [87], B. bovis (www.tigr.org), and Cryptosporidium hominis [88]. Within the analysis we also included Sir2 from yeast, other related species, and unicellular protozoan parasites. Bootstraps values are indicated for important nodes, where in all cases the upper number is the bootstrap using distance, the lower is the bootstrap using maximum likelihood. “-“ sign indicates a value below 50. Two Sir2 paralogues are a common feature of apicomplexan parasites. Sir2B paralogues (red branches) show strong support for the Sir2B clade, especially within Plasmodium species. Sir2B paralogues also groups together type IV sirtuins (SIRT6 and 7) with good support. Sir2A clade (blue branches) groups together Sir2A paralogues of apicomplexan species with excellent support. Sir2A's moderate grouping with SIRT5 and Archaeoglobus fulgidus Sir2-Af1 also shows a possible functional relationship with type III sirtuins. For more in depth analysis see Text S1. P. ber, P. berghei; P. yoe, P. yoellii; P. cha, P. chabaudi; P. viv, P. vivax; P. fal, P. falciparum; T. ann, T. annulata; T. parv, T. parva; T. gondi, T. gondii; B. bov, B. bovis; A. ful, A. fulgidus; H. sap, Homo sapiens; C. hom, C. hominis; T. pse, Thalassiosira pseudonana (diatom); G. lam, Giardia lamblia; K. lac, Kluyveromyces lactis; S. cer, S. cerevisiae; L. maj, Leishmania major.