title: The evolutionary trajectory of mitochondrial carrier family during metazoan evolution.
abstract: BACKGROUND
  Exploring metabolic evolution is a way to understand metabolic complexity. The substrate transport of mitochondrial carrier family (MCF) influences direct metabolic activities, making it possible to understand indirectly metabolic evolution from the evolution of substrate transport of MCF. However, the evolutionary study of substrate transport of MCF does not mean that all the concrete structures of mitochondrial carriers (MCs) must first be gained.
  
  
  RESULTS
  Here we studied the alternation of MCF structure and potential correlated functions of MCF during metazoan evolution. The data analysis indicates that the types of substrates transported by MCF as a whole were maintained during metazoan evolution. However, the size of the substrates transported by members of MCs continuously diminished during the evolutionary process. We have found that the ratio of hydrophobic amino acids at specific helix-helix interfaces increases significantly during vertebrate evolution. Amino acid's spatial positioning and the calculating of packing values both indicate the increase in the number of hydrophobic amino acids would lead to a more "tight" structure of the TR domain, which is in agreement with the trend of diminishing size of substrates transported by MCs. In addition, there was a significant increase in the number of carriers of MCF during vertebrate evolution.
  
  
  CONCLUSIONS
  We propose that the more "tight" TR structure generated by the increase of the hydrophobic amino acids at specific helix-helix interfaces during vertebrate evolution enhances the substrate selectivity of MCF, reflecting the evolutionary trajectory of MCF during metazoan evolution.
authors.affiliation: Jiangsu Diabetes Center, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, 22 Hankou Road, Nanjing, Jiangsu 210093, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Gong
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.forename: Meng
authors.initials: M
authors.lastname: Wang
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
authors.forename: Ke
authors.initials: K
authors.lastname: Zen
authors.forename: Chen-Yu
authors.initials: CY
authors.lastname: Zhang
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001692:Biological Transport / Q000235:genetics / Q000502:physiology; D019143:Evolution, Molecular; D033681:Mitochondrial Membrane Transport Proteins / Q000235:genetics*; D010802:Phylogeny; D013379:Substrate Specificity
chemical_list: D033681:Mitochondrial Membrane Transport Proteins