title: Quantitative and functional characterization of the hyper-conserved protein of Prochlorococcus and marine Synechococcus.
abstract: A large fraction of any bacterial genome consists of hypothetical protein-coding open reading frames (ORFs). While most of these ORFs are present only in one or a few sequenced genomes, a few are conserved, often across large phylogenetic distances. Such conservation provides clues to likely uncharacterized cellular functions that need to be elucidated. Marine cyanobacteria from the Prochlorococcus/marine Synechococcus clade are dominant bacteria in oceanic waters and are significant contributors to global primary production. A Hyper Conserved Protein (PSHCP) of unknown function is 100% conserved at the amino acid level in genomes of Prochlorococcus/marine Synechococcus, but lacks homologs outside of this clade. In this study we investigated Prochlorococcus marinus strains MED4 and MIT 9313 and Synechococcus sp. strain WH 8102 for the transcription of the PSHCP gene using RT-Q-PCR, for the presence of the protein product through quantitative immunoblotting, and for the protein's binding partners in a pull down assay. Significant transcription of the gene was detected in all strains. The PSHCP protein content varied between 8±1 fmol and 26±9 fmol per ug total protein, depending on the strain. The 50 S ribosomal protein L2, the Photosystem I protein PsaD and the Ycf48-like protein were found associated with the PSHCP protein in all strains and not appreciably or at all in control experiments. We hypothesize that PSHCP is a protein associated with the ribosome, and is possibly involved in photosystem assembly.
authors.affiliation: Department of Chemistry & Biochemistry, Mount Allison University, Sackville, NB, Canada.
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Whidden
authors.affiliation: Department of Chemistry & Biochemistry, Mount Allison University, Sackville, NB, Canada.
authors.forename: Katrina G
authors.initials: KG
authors.lastname: DeZeeuw
authors.affiliation: Department of Chemistry & Biochemistry, Mount Allison University, Sackville, NB, Canada.
authors.forename: Jackie K
authors.initials: JK
authors.lastname: Zorz
authors.affiliation: Atlantic Cancer Research Institute, Moncton, NB, Canada.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Joy
authors.affiliation: Atlantic Cancer Research Institute, Moncton, NB, Canada.
authors.forename: David A
authors.initials: DA
authors.lastname: Barnett
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, United States of America.
authors.forename: Milo S
authors.initials: MS
authors.lastname: Johnson
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, United States of America; Department of Computer Science, Dartmouth College, Hanover, New Hampshire, United States of America.
authors.forename: Olga
authors.initials: O
authors.lastname: Zhaxybayeva
authors.affiliation: Department of Chemistry & Biochemistry, Mount Allison University, Sackville, NB, Canada.
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Cockshutt
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism*; D017124:Conserved Sequence; D000458:Cyanobacteria / Q000737:chemistry / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D010940:Plant Proteins / Q000378:metabolism; D048929:Prochlorococcus / Q000737:chemistry* / Q000235:genetics; D025941:Protein Interaction Mapping; D012335:RNA, Ribosomal / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism; D046940:Synechococcus / Q000737:chemistry* / Q000235:genetics; D024363:Transcription Initiation Site
chemical_list: D001426:Bacterial Proteins; D010940:Plant Proteins; C070290:PsaD protein, cyanobacteria; D012335:RNA, Ribosomal; D012269:Ribosomal Proteins; C029466:ribosomal protein L2