title: N-ACYL HOMOSERINE LACTONe LACTONASE, AiiA, INACTIVATION OF QUORUM-SENSING AGONISTS PRODUCED BY CHLAMYDOMONAS REINHARDTII (CHLOROPHYTA) AND CHARACTERIZATION OF aiiA TRANSGENIC ALGAE(1).
abstract: Eukaryotes such as plants and the unicellular green alga Chlamydomonas reinhardtii P. A. Dang. produce and secrete compounds that mimic N-acyl homoserine lactone (AHL) bacterial quorum-sensing (QS) signals and alter QS-regulated gene expression in the associated bacteria. Here, we show that the set of C. reinhardtii signal-mimic compounds that activate the CepR AHL receptor of Burkholderia cepacia are susceptible to inactivation by AiiA, an AHL lactonase enzyme of Bacillus. Inactivation of these algal mimics by AiiA suggests that the CepR-stimulatory class of mimics produced by C. reinhardtii may have a conserved lactone ring structure in common with AHL QS signals. To examine the role of AHL mimic compounds in the interactions of C. reinhardtii with bacteria, the aiiA gene codon optimized for Chlamydomonas was generated for the expression of AiiA as a chimeric fusion with cyan fluorescent protein (AimC). Culture filtrates of transgenic strains expressing the fusion protein AimC had significantly reduced levels of CepR signal-mimic activities. When parental and transgenic algae were cultured with a natural pond water bacterial community, a morphologically distinct, AHL-producing isolate of Aeromonas veronii was observed to colonize the transgenic algal cultures and form biofilms more readily than the parental algal cultures, indicating that secretion of the CepR signal mimics by the alga can significantly affect its interactions with bacteria it encounters in natural environments. The parental alga was also able to sequester and/or destroy AHLs in its growth media to further disrupt or manipulate bacterial QS.
authors.affiliation: Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, USADepartment of Soil and Water Science, University of Florida-IFAS, Gainesville, Florida 32611, USADonald Danforth Plant Science Center, St. Louis, Missouri 63132, USADepartment of Soil and Water Science, University of Florida-IFAS, Gainesville, Florida 32611, USADonald Danforth Plant Science Center, St. Louis, Missouri 63132, USADepartment of Plant Sciences, University of California, Davis, California 95616, USA.
authors.forename: Sathish
authors.initials: S
authors.lastname: Rajamani
authors.affiliation: Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, USADepartment of Soil and Water Science, University of Florida-IFAS, Gainesville, Florida 32611, USADonald Danforth Plant Science Center, St. Louis, Missouri 63132, USADepartment of Soil and Water Science, University of Florida-IFAS, Gainesville, Florida 32611, USADonald Danforth Plant Science Center, St. Louis, Missouri 63132, USADepartment of Plant Sciences, University of California, Davis, California 95616, USA.
authors.forename: Max
authors.initials: M
authors.lastname: Teplitski
authors.affiliation: Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, USADepartment of Soil and Water Science, University of Florida-IFAS, Gainesville, Florida 32611, USADonald Danforth Plant Science Center, St. Louis, Missouri 63132, USADepartment of Soil and Water Science, University of Florida-IFAS, Gainesville, Florida 32611, USADonald Danforth Plant Science Center, St. Louis, Missouri 63132, USADepartment of Plant Sciences, University of California, Davis, California 95616, USA.
authors.forename: Anil
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, USADepartment of Soil and Water Science, University of Florida-IFAS, Gainesville, Florida 32611, USADonald Danforth Plant Science Center, St. Louis, Missouri 63132, USADepartment of Soil and Water Science, University of Florida-IFAS, Gainesville, Florida 32611, USADonald Danforth Plant Science Center, St. Louis, Missouri 63132, USADepartment of Plant Sciences, University of California, Davis, California 95616, USA.
authors.forename: Cory J
authors.initials: CJ
authors.lastname: Krediet
authors.affiliation: Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, USADepartment of Soil and Water Science, University of Florida-IFAS, Gainesville, Florida 32611, USADonald Danforth Plant Science Center, St. Louis, Missouri 63132, USADepartment of Soil and Water Science, University of Florida-IFAS, Gainesville, Florida 32611, USADonald Danforth Plant Science Center, St. Louis, Missouri 63132, USADepartment of Plant Sciences, University of California, Davis, California 95616, USA.
authors.forename: Richard T
authors.initials: RT
authors.lastname: Sayre
authors.affiliation: Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, USADepartment of Soil and Water Science, University of Florida-IFAS, Gainesville, Florida 32611, USADonald Danforth Plant Science Center, St. Louis, Missouri 63132, USADepartment of Soil and Water Science, University of Florida-IFAS, Gainesville, Florida 32611, USADonald Danforth Plant Science Center, St. Louis, Missouri 63132, USADepartment of Plant Sciences, University of California, Davis, California 95616, USA.
authors.forename: Wolfgang D
authors.initials: WD
authors.lastname: Bauer
keywords: AHL lactonase; Aeromonas veronii; Chlamydomonas reinhardtii; acyl homoserine lactone; algal mimics; cyan fluorescent protein; quorum sensing; yellow fluorescent protein