title: How the Sequence of a Gene Specifies Structural Symmetry in Proteins.
abstract: Internal symmetry is commonly observed in the majority of fundamental protein folds. Meanwhile, sufficient evidence suggests that nascent polypeptide chains of proteins have the potential to start the co-translational folding process and this process allows mRNA to contain additional information on protein structure. In this paper, we study the relationship between gene sequences and protein structures from the viewpoint of symmetry to explore how gene sequences code for structural symmetry in proteins. We found that, for a set of two-fold symmetric proteins from left-handed beta-helix fold, intragenic symmetry always exists in their corresponding gene sequences. Meanwhile, codon usage bias and local mRNA structure might be involved in modulating translation speed for the formation of structural symmetry: a major decrease of local codon usage bias in the middle of the codon sequence can be identified as a common feature; and major or consecutive decreases in local mRNA folding energy near the boundaries of the symmetric substructures can also be observed. The results suggest that gene duplication and fusion may be an evolutionarily conserved process for this protein fold. In addition, the usage of rare codons and the formation of higher order of secondary structure near the boundaries of symmetric substructures might have coevolved as conserved mechanisms to slow down translation elongation and to facilitate effective folding of symmetric substructures. These findings provide valuable insights into our understanding of the mechanisms of translation and its evolution, as well as the design of proteins via symmetric modules.
authors.affiliation: Department of Information Engineering, Shaoyang University, Shaoyang, Hunan, China.|Key Laboratory of Human-Machine Intelligence-Synergy Systems of Chinese Academy of Sciences (CAS), Shenzhen Institutes of Advanced Technology, CAS, Shenzhen, China.|Department of Biology, South University of Science and Technology of China, Shenzhen, China.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Shen
authors.affiliation: Department of Information Engineering, Shaoyang University, Shaoyang, Hunan, China.
authors.forename: Tongcheng
authors.initials: T
authors.lastname: Huang
authors.affiliation: Department of Biology, South University of Science and Technology of China, Shenzhen, China.
authors.forename: Guanyu
authors.initials: G
authors.lastname: Wang
authors.affiliation: Key Laboratory of Human-Machine Intelligence-Synergy Systems of Chinese Academy of Sciences (CAS), Shenzhen Institutes of Advanced Technology, CAS, Shenzhen, China.
authors.forename: Guanglin
authors.initials: G
authors.lastname: Li
mesh_terms: D001483:Base Sequence; D003062:Codon / Q000235:genetics*; D006801:Humans; D008962:Models, Theoretical; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D059370:RNA Folding / Q000235:genetics*; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics*
chemical_list: D003062:Codon; D011506:Proteins; D012333:RNA, Messenger