Horizontal Gene Transfer of Phytochelatin Synthases from Bacteria to Extremophilic Green Algae.
Transcriptomic sequencing together with bioinformatic analyses and an automated annotation process led us to identify novel phytochelatin synthase (PCS) genes from two extremophilic green algae (Chlamydomonas acidophila and Dunaliella acidophila). These genes are of intermediate length compared to known PCS genes from eukaryotes and PCS-like genes from prokaryotes. A detailed phylogenetic analysis gives new insight into the complicated evolutionary history of PCS genes and provides evidence for multiple horizontal gene transfer events from bacteria to eukaryotes within the gene family. A separate subgroup containing PCS-like genes within the PCS gene family is not supported since the PCS genes are monophyletic only when the PCS-like genes are included. The presence and functionality of the novel genes in the organisms were verified by genomic sequencing and qRT-PCR. Furthermore, the novel PCS gene in Chlamydomonas acidophila showed very strong induction by cadmium. Cloning and expression of the gene in Escherichia coli clearly improves its cadmium resistance. The gene in Dunaliella was not induced, most likely due to gene duplication.
Department of Agricultural Sciences, University of Helsinki, P.O. Box 27, 00014, Helsinki, Finland. sanna.olsson@helsinki.fi.|Centro de Astrobiología (CSIC-INTA), Carretera de Ajalvir Km 4, Torrejón de Ardoz, 28850, Madrid, Spain. sanna.olsson@helsinki.fi.
Sanna
S
Olsson
Centro de Astrobiología (CSIC-INTA), Carretera de Ajalvir Km 4, Torrejón de Ardoz, 28850, Madrid, Spain.|Bioarray, S.L., Parque Científico y Empresarial de la UMH. Edificio Quorum III, Avenida de la Universidad s/n, 03202, Elche, Alicante, Spain.
Vanessa
V
Penacho
Centro de Astrobiología (CSIC-INTA), Carretera de Ajalvir Km 4, Torrejón de Ardoz, 28850, Madrid, Spain.
Fernando
F
Puente-Sánchez
Departamento de Microbiología-III, Facultad de Biología, Universidad Complutense (UCM), Madrid, Spain.
Silvia
S
Díaz
Centro de Astrobiología (CSIC-INTA), Carretera de Ajalvir Km 4, Torrejón de Ardoz, 28850, Madrid, Spain.
José Eduardo
JE
Gonzalez-Pastor
Centro de Astrobiología (CSIC-INTA), Carretera de Ajalvir Km 4, Torrejón de Ardoz, 28850, Madrid, Spain.
Angeles
A
Aguilera
D019881:Aminoacyltransferases / Q000235:genetics*; D002104:Cadmium / Q000494:pharmacology*; D002696:Chlamydomonas / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics*; D000071825:Extremophiles / Q000235:genetics*; D016133:Polymerase Chain Reaction; D014873:Water Pollutants / Q000494:pharmacology; D014877:Water Pollution, Chemical
D014873:Water Pollutants; D002104:Cadmium; D019881:Aminoacyltransferases; C093784:glutathione gamma-glutamylcysteinyltransferase
Acidophile; Cadmium; Chlamydomonas acidophila; Dunaliella acidophila; Heavy metal tolerance