title: Preferential expression of one beta-tubulin gene during flagellate development in Physarum.
abstract: The microbial eukaryote Physarum polycephalum displays several distinct cell types in its life cycle, including amoebae, flagellates and plasmodia. Despite its relative simplicity, Physarum has a tubulin gene family of complexity comparable to that of Drosophila. We have identified beta-tubulin cDNAs from Physarum that are derived from the betA beta-tubulin locus and encode beta 1A tubulin. We have also identified a partial cDNA for the unlinked betB beta-tubulin gene, which encodes beta 1B tubulin. The polypeptide sequences encoded by betA and betB show 99% identity, but the nucleotide sequences show only 85% identity, consistent with an ancient duplication of these genes. The betB gene is expressed in amoebae, flagellates and plasmodia, whereas betA is expressed only in amoebae and flagellates. During the amoeba-flagellate transition the level of betA transcript increases over 100-fold, while the level of betB transcript changes very little. Thus Physarum has a mechanism for regulating the level of discrete beta-tubulin transcripts differentially during flagellate development. A need for this differential regulation could account for the maintenance of the virtually isocoding betA and betB beta-tubulin genes.
authors.affiliation: McArdle Laboratory for Cancer Research, University of Wisconsin, Madison 53706.
authors.forename: E C
authors.initials: EC
authors.lastname: Paul
authors.forename: G L
authors.initials: GL
authors.lastname: Buchschacher
authors.forename: D B
authors.initials: DB
authors.lastname: Cunningham
authors.forename: W F
authors.initials: WF
authors.lastname: Dove
authors.forename: T G
authors.initials: TG
authors.lastname: Burland
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D004271:DNA, Fungal / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics; D015870:Gene Expression; D008969:Molecular Sequence Data; D005810:Multigene Family; D010804:Physarum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D016053:RNA, Protozoan / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014404:Tubulin / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D004271:DNA, Fungal; D016054:DNA, Protozoan; D012331:RNA, Fungal; D016053:RNA, Protozoan; D014404:Tubulin