title: Characterization of the hemoglobin of the backswimmer Anisops deanei (Hemiptera).
abstract: While O(2)-binding hemoglobin-like proteins are present in many insects, prominent amounts of hemoglobin have only been found in a few species. Backswimmers of the genera Anisops and Buenoa (Notonectidae) have high concentrations of hemoglobin in the large tracheal cells of the abdomen. Oxygen from the hemoglobin is delivered to a gas bubble and controls the buoyant density, which enables the bugs to maintain their position without swimming and to remain stationary in the mid-water zone where they hunt for prey. We have obtained the cDNA sequences of three Anisops deanei hemoglobin chains by RT-PCR and RACE techniques. The deduced amino acid sequences show an unusual insertion of a single amino acid in the conserved helix E, but this does not affect protein stability or ligand binding kinetics. Recombinant A. deanei hemoglobin has an oxygen affinity of P(50) = 2.4 kPa (18 torr) and reveals the presence of a dimeric fraction or two different conformations. The absorption spectra demonstrate that the Anisops hemoglobin is a typical pentacoordinate globin. Phylogenetic analyses show that the backswimmer hemoglobins evolved within Heteroptera and most likely originated from an intracellular hemoglobin with divergent function.
authors.affiliation: Institute of Zoology, University of Hamburg, Biocenter Grindel, Martin-Luther-King-Platz 3, D-20146 Hamburg, Germany.
authors.forename: Agnes
authors.initials: A
authors.lastname: Wawrowski
authors.forename: Philip G D
authors.initials: PG
authors.lastname: Matthews
authors.forename: Eva
authors.initials: E
authors.lastname: Gleixner
authors.forename: Laurent
authors.initials: L
authors.lastname: Kiger
authors.forename: Michael C
authors.initials: MC
authors.lastname: Marden
authors.forename: Thomas
authors.initials: T
authors.lastname: Hankeln
authors.forename: Thorsten
authors.initials: T
authors.lastname: Burmester
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D006430:Hemiptera / Q000737:chemistry*; D006454:Hemoglobins / Q000737:chemistry*; D006801:Humans; D019476:Insect Proteins / Q000737:chemistry*; D007700:Kinetics; D008024:Ligands; D008969:Molecular Sequence Data; D010100:Oxygen / Q000737:chemistry; D010802:Phylogeny; D017422:Sequence Analysis, DNA
chemical_list: D006454:Hemoglobins; D019476:Insect Proteins; D008024:Ligands; D010100:Oxygen