title: Three globin lineages belonging to two structural classes in genomes from the three kingdoms of life.
abstract: Although most globins, including the N-terminal domains within chimeric proteins such as flavohemoglobins and globin-coupled sensors, exhibit a 3/3 helical sandwich structure, many bacterial, plant, and ciliate globins have a 2/2 helical sandwich structure. We carried out a comprehensive survey of globins in the genomes from the three kingdoms of life. Bayesian phylogenetic trees based on manually aligned sequences indicate the possibility of past horizontal globin gene transfers from bacteria to eukaryotes. blastp searches revealed the presence of 3/3 single-domain globins related to the globin domains of the bacterial and fungal flavohemoglobins in many bacteria, a red alga, and a diatom. Iterated psi-blast searches based on groups of globin sequences found that only the single-domain globins and flavohemoglobins recognize the eukaryote 3/3 globins, including vertebrate neuroglobins, alpha- and beta-globins, and cytoglobins. The 2/2 globins recognize the flavohemoglobins, as do the globin coupled sensors and the closely related single-domain protoglobins. However, the 2/2 globins and the globin-coupled sensors do not recognize each other. Thus, all globins appear to be distributed among three lineages: (i) the 3/3 plant and metazoan globins, single-domain globins, and flavohemoglobins; (ii) the bacterial 3/3 globin-coupled sensors and protoglobins; and (iii) the bacterial, plant, and ciliate 2/2 globins. The three lineages may have evolved from an ancestral 3/3 or 2/2 globin. Furthermore, it appears likely that the predominant functions of globins are enzymatic and that oxygen transport is a specialized development that accompanied the evolution of metazoans.
authors.affiliation: Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI 48201, USA. svinogra@med.wayne.edu
authors.forename: Serge N
authors.initials: SN
authors.lastname: Vinogradov
authors.forename: David
authors.initials: D
authors.lastname: Hoogewijs
authors.forename: Xavier
authors.initials: X
authors.lastname: Bailly
authors.forename: Raúl
authors.initials: R
authors.lastname: Arredondo-Peter
authors.forename: Michel
authors.initials: M
authors.lastname: Guertin
authors.forename: Julian
authors.initials: J
authors.lastname: Gough
authors.forename: Sylvia
authors.initials: S
authors.lastname: Dewilde
authors.forename: Luc
authors.initials: L
authors.lastname: Moens
authors.forename: Jacques R
authors.initials: JR
authors.lastname: Vanfleteren
mesh_terms: D001499:Bayes Theorem; D019295:Computational Biology; D019143:Evolution, Molecular; D016678:Genome; D005914:Globins / Q000235:genetics*; D008957:Models, Genetic; D010802:Phylogeny; D016415:Sequence Alignment; D013045:Species Specificity
chemical_list: D005914:Globins