title: Exonic splicing signals impose constraints upon the evolution of enzymatic activity.
abstract: Exon splicing enhancers (ESEs) overlap with amino acid coding sequences implying a dual evolutionary selective pressure. In this study, we map ESEs in the placental alkaline phosphatase gene (ALPP), absent in the corresponding exon of the ancestral tissue-non-specific alkaline phosphatase gene (ALPL). The ESEs are associated with amino acid differences between the transcripts in an area otherwise conserved. We switched out the ALPP ESEs sequences with the sequence from the related ALPL, introducing the associated amino acid changes. The resulting enzymes, produced by cDNA expression, showed different kinetic characteristics than ALPL and ALPP. In the organism, this enzyme will never be subjected to selection because gene splicing analysis shows exon skipping due to loss of the ESE. Our data prove that ESEs restrict the evolution of enzymatic activity. Thus, suboptimal proteins may exist in scenarios when coding nucleotide changes and consequent amino acid variation cannot be reconciled with the splicing function.
authors.affiliation: Molecular Pathology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano 99, 34149 Trieste, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Falanga
authors.affiliation: Bioinformatics Group, Department of Molecular Biology, Division of Biology, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, Croatia.
authors.forename: Ozren
authors.initials: O
authors.lastname: Stojanović
authors.affiliation: Sanford Children's Health Research Center, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Tina
authors.initials: T
authors.lastname: Kiffer-Moreira
authors.affiliation: Bioinformatics Group, Department of Molecular Biology, Division of Biology, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, Croatia.
authors.forename: Sofia
authors.initials: S
authors.lastname: Pinto
authors.affiliation: Sanford Children's Health Research Center, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Millán
authors.affiliation: Bioinformatics Group, Department of Molecular Biology, Division of Biology, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, Croatia Department of Informatics, University of Oslo, PO Box 1080 Blindern, NO-0316 Oslo, Norway.
authors.forename: Kristian
authors.initials: K
authors.lastname: Vlahoviček
authors.affiliation: Molecular Pathology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano 99, 34149 Trieste, Italy barallem@icgeb.org.
authors.forename: Marco
authors.initials: M
authors.lastname: Baralle
mesh_terms: D000469:Alkaline Phosphatase / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D020134:Catalytic Domain; D002522:Chlorocebus aethiops; D003198:Computer Simulation; D019143:Evolution, Molecular; D005091:Exons; D058851:GPI-Linked Proteins / Q000737:chemistry / Q000235:genetics; D020440:Gene Duplication; D015894:Genome, Human; D006367:HeLa Cells; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics*; D007700:Kinetics; D008957:Models, Genetic; D008969:Molecular Sequence Data; D022821:RNA Splice Sites; D012984:Software
chemical_list: D058851:GPI-Linked Proteins; D007527:Isoenzymes; D022821:RNA Splice Sites; C548269:ALPG protein, human; D000469:Alkaline Phosphatase; C019839:alkaline phosphatase, placental