title: The Rickettsia Endosymbiont of Ixodes pacificus Contains All the Genes of De Novo Folate Biosynthesis.
abstract: Ticks and other arthropods often are hosts to nutrient providing bacterial endosymbionts, which contribute to their host's fitness by supplying nutrients such as vitamins and amino acids. It has been detected, in our lab, that Ixodes pacificus is host to Rickettsia species phylotype G021. This endosymbiont is predominantly present, and 100% maternally transmitted in I. pacificus. To study roles of phylotype G021 in I. pacificus, bioinformatic and molecular approaches were carried out. MUMmer genome alignments of whole genome sequence of I. scapularis, a close relative to I. pacificus, against completely sequenced genomes of R. bellii OSU85-389, R. conorii, and R. felis, identified 8,190 unique sequences that are homologous to Rickettsia sequences in the NCBI Trace Archive. MetaCyc metabolic reconstructions revealed that all folate gene orthologues (folA, folC, folE, folKP, ptpS) required for de novo folate biosynthesis are present in the genome of Rickettsia buchneri in I. scapularis. To examine the metabolic capability of phylotype G021 in I. pacificus, genes of the folate biosynthesis pathway of the bacterium were PCR amplified using degenerate primers. BLAST searches identified that nucleotide sequences of the folA, folC, folE, folKP, and ptpS genes possess 98.6%, 98.8%, 98.9%, 98.5% and 99.0% identity respectively to the corresponding genes of Rickettsia buchneri. Phylogenetic tree constructions show that the folate genes of phylotype G021 and homologous genes from various Rickettsia species are monophyletic. This study has shown that all folate genes exist in the genome of Rickettsia species phylotype G021 and that this bacterium has the genetic capability for de novo folate synthesis.
authors.affiliation: Department of Biological Sciences, Humboldt State University, Arcata, California, United States of America.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Hunter
authors.affiliation: Department of Biological Sciences, Humboldt State University, Arcata, California, United States of America.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Torkelson
authors.affiliation: Department of Biological Sciences, Humboldt State University, Arcata, California, United States of America.
authors.forename: James
authors.initials: J
authors.lastname: Bodnar
authors.affiliation: Center for Outcomes Research and Evaluation, Yale School of Medicine, New Haven, Connecticut, United States of America.
authors.forename: Bobak
authors.initials: B
authors.lastname: Mortazavi
authors.affiliation: Department of Biological Sciences, Humboldt State University, Arcata, California, United States of America.
authors.forename: Timothy
authors.initials: T
authors.lastname: Laurent
authors.affiliation: Department of Biological Sciences, Humboldt State University, Arcata, California, United States of America.
authors.forename: Jeff
authors.initials: J
authors.lastname: Deason
authors.affiliation: Department of Biological Sciences, Humboldt State University, Arcata, California, United States of America.
authors.forename: Khanhkeo
authors.initials: K
authors.lastname: Thephavongsa
authors.affiliation: Department of Biological Sciences, Humboldt State University, Arcata, California, United States of America.
authors.forename: Jianmin
authors.initials: J
authors.lastname: Zhong
mesh_terms: D000818:Animals; D019295:Computational Biology; D005492:Folic Acid / Q000096:biosynthesis*; D018884:Ixodes / Q000235:genetics / Q000382:microbiology*; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012281:Rickettsia / Q000235:genetics*; D012282:Rickettsia Infections / Q000235:genetics* / Q000382:microbiology; D013559:Symbiosis / Q000235:genetics*; D013984:Tick Infestations / Q000235:genetics* / Q000382:microbiology
chemical_list: D005492:Folic Acid