title: Cloning and heterologous expression of chlorophyll a synthase in Rhodobacter sphaeroides.
abstract: Rhodobacter sphaeroides is a purple non-sulfur bacterium which photoheterotrophically produces hydrogen from organic acids under anaerobic conditions. A gene coding for putative chlorophyll a synthase (chlG) from cyanobacterium Prochlorococcus marinus was amplified by nested polymerase chain reaction and cloned into an inducible-expression plasmid which was subsequently transferred to R. sphaeroides for heterologous expression. Induced expression of chlG in R. sphaeroides led to changes in light absorption spectrum within 400-700 nm. The hydrogen production capacity of the mutant strain was evaluated on hydrogen production medium with 15 mM malate and 2 mM glutamate. Hydrogen yield and productivity were increased by 13.6 and 22.6%, respectively, compared to the wild type strain. The results demonstrated the feasibility of genetic engineering to combine chlorophyll and bacteriochlorophyll biosynthetic pathways which utilize common intermediates. Heterologous expression of key enzymes from biosynthetic pathways of various pigments is proposed here as a general strategy to improve absorption spectra and yield of photosynthesis and hydrogen gas production in bacteria.
authors.affiliation: Department of Molecular Biology and Genetics, Middle East Technical University, Ankara, Turkey.
authors.forename: Emre M
authors.initials: EM
authors.lastname: Ipekoğlu
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, Toronto, Canada.
authors.forename: Koray
authors.initials: K
authors.lastname: Göçmen
authors.affiliation: Department of Biological Sciences, Middle East Technical University, Ankara, Turkey.|Department of Agronomy, University of Florida, Gainesville, Florida, USA.
authors.forename: Mehmet T
authors.initials: MT
authors.lastname: Öz
authors.affiliation: Department of Biological Sciences, Middle East Technical University, Ankara, Turkey.
authors.forename: Muazzez
authors.initials: M
authors.lastname: Gürgan
authors.affiliation: Department of Biological Sciences, Middle East Technical University, Ankara, Turkey.
authors.forename: Meral
authors.initials: M
authors.lastname: Yücel
mesh_terms: D001429:Bacteriochlorophylls / Q000235:genetics; D019729:Carbon-Oxygen Ligases / Q000096:biosynthesis* / Q000235:genetics*; D002734:Chlorophyll / Q000096:biosynthesis* / Q000235:genetics; D000077194:Chlorophyll A; D003001:Cloning, Molecular; D015870:Gene Expression; D005798:Genes, Bacterial; D005818:Genetic Engineering / Q000379:methods*; D018698:Glutamic Acid / Q000494:pharmacology; D006859:Hydrogen / Q000378:metabolism; D008293:Malates / Q000494:pharmacology; D009154:Mutation; D010788:Photosynthesis / Q000235:genetics; D010957:Plasmids; D016133:Polymerase Chain Reaction; D048929:Prochlorococcus / Q000201:enzymology* / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis; D012242:Rhodobacter sphaeroides / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism
chemical_list: D001429:Bacteriochlorophylls; D008293:Malates; D011994:Recombinant Proteins; D002734:Chlorophyll; D018698:Glutamic Acid; D006859:Hydrogen; C030298:malic acid; D019729:Carbon-Oxygen Ligases; C105512:bacteriochlorophyll a synthase; D000077194:Chlorophyll A
keywords: Chlorophyll a synthase; Prochlorococcus marinus; Rhodobacter sphaeroides; hydrogen production; photosynthesis