title: Polygalacturonase from Sitophilus oryzae: possible horizontal transfer of a pectinase gene from fungi to weevils.
abstract: Endo-polygalacturonase, one of the group of enzymes known collectively as pectinases, is widely distributed in bacteria, plants and fungi. The enzyme has also been found in several weevil species and a few other insects, such as aphids, but not in Drosophila melanogaster, Anopheles gambiae, or Caenorhabditis elegans or, as far as is known, in any more primitive animal species. What, then, is the genetic origin of the polygalacturonases in weevils? Since some weevil species harbor symbiotic microorganisms, it has been suggested, reasonably, that the symbionts' genomes of both aphids and weevils, rather than the insects' genomes, could encode polygalacturonase. We report here the cloning of a cDNA that encodes endo-polygalacturonase in the rice weevil, Sitophilus oryzae (L.), and investigations based on the cloned cDNA. Our results, which include analysis of genes in antibiotic-treated rice weevils, indicate that the enzyme is, in fact, encoded by the insect genome. Given the apparent absence of the gene in much of the rest of the animal kingdom, it is therefore likely that the rice weevil polygalacturonase gene was incorporated into the weevil's genome by horizontal transfer, possibly from a fungus.
authors.affiliation: Department of Entomology, Kansas State University, Manhattan, Kansas 66506, USA.
authors.forename: Zhicheng
authors.initials: Z
authors.lastname: Shen
authors.forename: Michael
authors.initials: M
authors.lastname: Denton
authors.forename: Navdeep
authors.initials: N
authors.lastname: Mutti
authors.forename: Kirk
authors.initials: K
authors.lastname: Pappan
authors.forename: Michael R
authors.initials: MR
authors.lastname: Kanost
authors.forename: John C
authors.initials: JC
authors.lastname: Reese
authors.forename: Gerald R
authors.initials: GR
authors.lastname: Reeck
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005658:Fungi / Q000201:enzymology* / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D022761:Gene Transfer, Horizontal; D008969:Molecular Sequence Data; D011096:Polygalacturonase / Q000235:genetics*; D048889:Weevils / Q000201:enzymology* / Q000235:genetics*
chemical_list: D011096:Polygalacturonase