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Barnhart-Dailey M, Zhang Y, Zhang R, Anthony SM, Aaron JS, Miller ES, Lindsey JS, Timlin JA. Cellular localization of tolyporphins, unusual tetrapyrroles, in a microbial photosynthetic community determined using hyperspectral confocal fluorescence microscopy. Photosynth Res 2019; 141:259-271. [PMID: 30903482 DOI: 10.1007/s11120-019-00625-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 11/26/2018] [Indexed: 06/09/2023]
Abstract
The cyanobacterial culture HT-58-2, composed of a filamentous cyanobacterium and accompanying community bacteria, produces chlorophyll a as well as the tetrapyrrole macrocycles known as tolyporphins. Almost all known tolyporphins (A-M except K) contain a dioxobacteriochlorin chromophore and exhibit an absorption spectrum somewhat similar to that of chlorophyll a. Here, hyperspectral confocal fluorescence microscopy was employed to noninvasively probe the locale of tolyporphins within live cells under various growth conditions (media, illumination, culture age). Cultures grown in nitrate-depleted media (BG-110 vs. nitrate-rich, BG-11) are known to increase the production of tolyporphins by orders of magnitude (rivaling that of chlorophyll a) over a period of 30-45 days. Multivariate curve resolution (MCR) was applied to an image set containing images from each condition to obtain pure component spectra of the endogenous pigments. The relative abundances of these components were then calculated for individual pixels in each image in the entire set, and 3D-volume renderings were obtained. At 30 days in media with or without nitrate, the chlorophyll a and phycobilisomes (combined phycocyanin and phycobilin components) co-localize in the filament outer cytoplasmic region. Tolyporphins localize in a distinct peripheral pattern in cells grown in BG-110 versus a diffuse pattern (mimicking the chlorophyll a localization) upon growth in BG-11. In BG-110, distinct puncta of tolyporphins were commonly found at the septa between cells and at the end of filaments. This work quantifies the relative abundance and envelope localization of tolyporphins in single cells, and illustrates the ability to identify novel tetrapyrroles in the presence of chlorophyll a in a photosynthetic microorganism within a non-axenic culture.
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Affiliation(s)
- Meghan Barnhart-Dailey
- Bioenergy and Defense Technologies, Sandia National Laboratories, Albuquerque, NM, 87185-0895, USA
| | - Yunlong Zhang
- Department of Chemistry, North Carolina State University, Raleigh, NC, 27695-8204, USA
| | - Ran Zhang
- Department of Chemistry, North Carolina State University, Raleigh, NC, 27695-8204, USA
| | - Stephen M Anthony
- Bioenergy and Defense Technologies, Sandia National Laboratories, Albuquerque, NM, 87185-0895, USA
| | - Jesse S Aaron
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, 20147, USA
| | - Eric S Miller
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 27695-7615, USA
| | - Jonathan S Lindsey
- Department of Chemistry, North Carolina State University, Raleigh, NC, 27695-8204, USA.
| | - Jerilyn A Timlin
- Bioenergy and Defense Technologies, Sandia National Laboratories, Albuquerque, NM, 87185-0895, USA.
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