title: Evolutionary and functional insights into Leishmania META1: evidence for lateral gene transfer and a role for META1 in secretion.
abstract: BACKGROUND
  Leishmania META1 has for long been a candidate molecule for involvement in virulence: META1 transcript and protein are up-regulated in metacyclic Leishmania. Yet, how META1 contributes to virulence remains unclear. We sought insights into the possible functions of META1 by studying its evolutionary origins.
  
  
  RESULTS
  Using multiple criteria including sequence similarity, nucleotide composition, phylogenetic analysis and selection pressure on gene sequence, we present evidence that META1 originated in trypanosomatids as a result of a lateral gene transfer of a bacterial heat-inducible protein, HslJ. Furthermore, within the Leishmania genome, META1 sequence is under negative selection pressure against change/substitution. Using homology modeling of Leishmania META1 based on solved NMR structure of HslJ, we show that META1 and HslJ share a similar structural fold. The best hit for other proteins with similar fold is MxiM, a protein involved in the type III secretion system in Shigella. The striking structural similarity shared by META1, HslJ and MxiM suggests a possibility of shared functions. Upon structural superposition with MxiM, we have observed a putative hydrophobic cavity in META1. Mutagenesis of select hydrophobic residues in this cavity affects the secretion of the secreted acid phosphatase (SAP), indicating META1's involvement in secretory processes in Leishmania.
  
  
  CONCLUSIONS
  Overall, this work uses an evolutionary biology approach, 3D-modeling and site-directed mutagenesis to arrive at new insights into functions of Leishmania META1.
authors.affiliation: Centre for Cellular and Molecular Biology, Council for Scientific and Industrial Research, Uppal Road, Hyderabad - 500 007, Andhra Pradesh, India.
authors.forename: Vidhi
authors.initials: V
authors.lastname: Puri
authors.forename: Aneesh
authors.initials: A
authors.lastname: Goyal
authors.forename: Rajan
authors.initials: R
authors.lastname: Sankaranarayanan
authors.forename: Anton J
authors.initials: AJ
authors.lastname: Enright
authors.forename: Tushar
authors.initials: T
authors.lastname: Vaidya
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001482:Base Composition; D016054:DNA, Protozoan / Q000235:genetics; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D007891:Leishmania / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D012641:Selection, Genetic; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D016054:DNA, Protozoan; C100528:Meta1 protein, Leishmania major; D015800:Protozoan Proteins
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