Effect of temperature on photosynthesis and growth in marine Synechococcus spp.
In this study, we develop a mechanistic understanding of how temperature affects growth and photosynthesis in 10 geographically and physiologically diverse strains of Synechococcus spp. We found that Synechococcus spp. are able to regulate photochemistry over a range of temperatures by using state transitions and altering the abundance of photosynthetic proteins. These strategies minimize photosystem II (PSII) photodamage by keeping the photosynthetic electron transport chain (ETC), and hence PSII reaction centers, more oxidized. At temperatures that approach the optimal growth temperature of each strain when cellular demand for reduced nicotinamide adenine dinucleotide phosphate (NADPH) is greatest, the phycobilisome (PBS) antenna associates with PSII, increasing the flux of electrons into the ETC. By contrast, under low temperature, when slow growth lowers the demand for NADPH and linear ETC declines, the PBS associates with photosystem I. This favors oxidation of PSII and potential increase in cyclic electron flow. For Synechococcus sp. WH8102, growth at higher temperatures led to an increase in the abundance of PBS pigment proteins, as well as higher abundance of subunits of the PSII, photosystem I, and cytochrome b6f complexes. This would allow cells to increase photosynthetic electron flux to meet the metabolic requirement for NADPH during rapid growth. These PBS-based temperature acclimation strategies may underlie the larger geographic range of this group relative to Prochlorococcus spp., which lack a PBS.
Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts 02543.
Katherine R M
KR
Mackey
Adina
A
Paytan
Ken
K
Caldeira
Arthur R
AR
Grossman
Dawn
D
Moran
Matthew
M
McIlvin
Mak A
MA
Saito
D059001:Aquatic Organisms / Q000254:growth & development* / Q000502:physiology* / Q000528:radiation effects; D001426:Bacterial Proteins / Q000378:metabolism; D016000:Cluster Analysis; D004579:Electron Transport / Q000528:radiation effects; D005453:Fluorescence; D005843:Geography; D010788:Photosynthesis / Q000502:physiology* / Q000528:radiation effects; D045332:Photosystem II Protein Complex / Q000378:metabolism; D045524:Phycobilisomes / Q000378:metabolism / Q000528:radiation effects; D040901:Proteomics; D013499:Surface Properties; D046940:Synechococcus / Q000254:growth & development* / Q000502:physiology* / Q000528:radiation effects; D013696:Temperature
D001426:Bacterial Proteins; D045332:Photosystem II Protein Complex; D045524:Phycobilisomes