Annexin-like proteins in a 20 member Giardia-specific protein family associated with different > 자유게시판

Annexin-like proteins in a 20 member Giardia-specific protein family associated with different cytoskeleton and membrane structures [27]. All annexin-like proteins in Spironucleus are more similar to annexins in other eukaryotes than to any alpha-giardin. For example, the putative amino acid sequence of contig160 shows 40 identity to Xenopus laevis annexin A7, but only 27 identity to G. intestinalis alpha-5 giardin. The most parsimonious explanation probably is that alpha-giardins evolved specifically in the Giardia branch from typical eukaryotic annexins. However, an alternative explanation for the large divergence of annexin-like proteins in diplomonads is that one of the two studied lineages obtained the proteins via lateral gene transfer. The third class of genes consists of 58 sequences without matches in the G. intestinalis genome (Additional files 5 and 6). Metabolic functions dominate among the 26 that do have putative annotations, including several peptidases, desulfoferredoxin, fructokinase, cartenoid isomerase PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/15501003 and rubrerythrin (Additional file 6), suggesting metabolic adaptation as a selection force for their maintenance in the S. barkhanus genome. Detailed phylogenetic analyses, such as for selenophosphate synthetase (Figure 1A), would be necessary to determine the origin of these genes; they have either been gained in the Spironucleus lineage or been lost in the Giardia lineage. Lateral gene transfer has indeed previously been shown to contribute to adaptation within diplomonads and other eukaryotes [7,14,21,28-30]. In fact, ten of the S. barkhanus sequences have indeed close homologs among proteins identified as recently introduced via lateral gene transfer into the S. Sorafenib (Tosylate) salmonicida genome (Additional file 6). Several of the other proteins also likely represent acquisitions in the Spironucleus lineage, some maybe after the divergence between S. barkhanus and S. salmonicida. At any rate, this class contains candidate genes for the understanding of the diversifications of diplomonads, regardless of their origins, as exemplified below.A triple function of UGA as sole termination codon, selenocysteine codon and polyadenylation signalSpironucleus uses an alternative genetic code; UAA and UAG encode glutamine, whereas UGA is the sole termination codon [17]. A putative selenocysteine tRNA (SelC) was identified in the S. salmonicida genome indicating that all 64 codons might be used to encode amino acids in this organism [14]. Here we discovered a putative selenophosphate synthetase (SelD), an enzyme marker for selenium utilization [31]. A phylogenetic analysis shows the S. barkhanus homolog nested within bacterial SelD sequences (Figure 1A). Furthermore, a S. salmonicida EST with 40 identity over 238 amino acids to ciliateRoxstr -Lindquist et al. BMC Genomics 2010, 11:258 http://www.biomedcentral.com/1471-2164/11/Page 4 ofA57 0.82 0.51 97 1.00 0.58 0.57 1.00 0.Clostridium butyricum (182417647) Clostridium perfringens (18311100) Thermosinus carboxydivorans (121535357) 0.99 Saccharopolyspora erythraea (134100098) 0.59 Haemophilus ducreyi (57013076) Ralstonia metallidurans (94312788) 1.00 Gemmata obscuriglobus (168699594) Spironucleus barkhanus Reinekea sp. MED297(88798618) 68 Synechococcus sp. CC9605 (78211738) 0.99 Marinobacter sp. ELB17 (126668989) 90 0.78 Roseobacter sp. AzwK-3b (149914190) 1.00 90 Sulfitobacter sp. NAS-14.1 (83953157) 1.00 Chlorobium phaeobacteroides (119356175) 58 96 Geobacter metallireducens (78224404) 0.65.