Engineered biosynthesis of bacteriochlorophyll g_F in Rhodobacter sphaeroides

Ortega-Ramos, Marcia, Canniffe, Daniel P ORCID: 0000-0002-5022-0437, Radle, Matthew I, Hunter, C Neil, Bryant, Donald A and Golbeck, John H (2018) Engineered biosynthesis of bacteriochlorophyll g_F in Rhodobacter sphaeroides BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS, 1859 (7). pp. 501-509. ISSN 0005-2728, 1879-2650

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Abstract

Engineering photosynthetic bacteria to utilize a heterologous reaction center that contains a different (bacterio) chlorophyll could improve solar energy conversion efficiency by allowing cells to absorb a broader range of the solar spectrum. One promising candidate is the homodimeric type I reaction center from Heliobacterium modesticaldum. It is the simplest known reaction center and uses bacteriochlorophyll (BChl) g, which absorbs in the near-infrared region of the spectrum. Like the more common BChls a and b, BChl g is a true bacteriochlorin. It carries characteristic C3-vinyl and C8-ethylidene groups, the latter shared with BChl b. The purple phototrophic bacterium Rhodobacter (Rba.) sphaeroides was chosen as the platform into which the engineered production of BChl g<inf>F</inf>, where F is farnesyl, was attempted. Using a strain of Rba. sphaeroides that produces BChl b<inf>P</inf>, where P is phytyl, rather than the native BChl a<inf>P</inf>, we deleted bchF, a gene that encodes an enzyme responsible for the hydration of the C3-vinyl group of a precursor of BChls. This led to the production of BChl g<inf>P</inf>. Next, the crtE gene was deleted, thereby producing BChl g carrying a THF (tetrahydrofarnesol) moiety. Additionally, the bchG^Rs gene from Rba. sphaeroides was replaced with bchG^Hm from Hba. modesticaldum. To prevent reduction of the tail, bchP was deleted, which yielded BChl g<inf>F</inf>. The construction of a strain producing BChl g<inf>F</inf> validates the biosynthetic pathway established for its synthesis and satisfies a precondition for assembling the simplest reaction center in a heterologous organism, namely the biosynthesis of its native pigment, BChl g<inf>F</inf>.

Item Type:	Article
Uncontrolled Keywords:	Photosynthesis, Heliobacteria, Purple bacteria, Bacteriochlorophyll g, Biosynthetic pathway
Depositing User:	Symplectic Admin
Date Deposited:	17 Jan 2019 09:27
Last Modified:	16 Jun 2026 14:21
DOI:	10.1016/j.bbabio.2018.02.006
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3031303
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