Abstract
SAR11 bacteria are small, heterotrophic, marine alphaproteobacteria found throughout the oceans. They thrive at the low nutrient concentrations typical of open ocean conditions, although the adaptations required for life under those conditions are not well understood. To illuminate this issue, we used cryo-electron tomography to study "Candidatus Pelagibacter ubique" strain HTCC1062, a member of the SAR11 clade. Our results revealed its cellular dimensions and details of its intracellular organization. Frozen-hydrated cells, which were preserved in a life-like state, had an average cell volume (enclosed by the outer membrane) of 0.037 ± 0.011 μm3. Strikingly, the periplasmic space occupied ~20% to 50% of the total cell volume in log-phase cells and ~50% to 70% in stationary-phase cells. The nucleoid occupied the convex side of the crescent-shaped cells and the ribosomes predominantly occupied the concave side, at a relatively high concentration of 10,000 to 12,000 ribosomes/μm3. Outer membrane pore complexes, likely composed of PilQ, were frequently observed in both log-phase and stationary-phase cells. Long filaments, most likely type IV pili, were found on dividing cells. The physical dimensions, intracellular organization, and morphological changes throughout the life cycle of "Ca. Pelagibacter ubique" provide structural insights into the functional adaptions of these oligotrophic ultramicrobacteria to their habitat.
| Original language | English (US) |
|---|---|
| Article number | e02807-16 |
| Journal | Applied and Environmental Microbiology |
| Volume | 83 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jan 1 2017 |
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Keywords
- Cryo-electron tomography
- PilQ
- SAR11
- Type IV pili
- Ultramicrobacteria
ASJC Scopus subject areas
- Biotechnology
- Food Science
- Applied Microbiology and Biotechnology
- Ecology
Cite this
Three-dimensional structure of the ultraoligotrophic marine bacterium "Candidatus pelagibacter ubique". / Zhao, Xiaowei; Schwartz, Cindi L.; Pierson, Jason; Giovannoni, Stephen J.; McIntosh, J. Richard; Nicastro, Daniela.
In: Applied and Environmental Microbiology, Vol. 83, No. 3, e02807-16, 01.01.2017.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Three-dimensional structure of the ultraoligotrophic marine bacterium "Candidatus pelagibacter ubique"
AU - Zhao, Xiaowei
AU - Schwartz, Cindi L.
AU - Pierson, Jason
AU - Giovannoni, Stephen J.
AU - McIntosh, J. Richard
AU - Nicastro, Daniela
PY - 2017/1/1
Y1 - 2017/1/1
N2 - SAR11 bacteria are small, heterotrophic, marine alphaproteobacteria found throughout the oceans. They thrive at the low nutrient concentrations typical of open ocean conditions, although the adaptations required for life under those conditions are not well understood. To illuminate this issue, we used cryo-electron tomography to study "Candidatus Pelagibacter ubique" strain HTCC1062, a member of the SAR11 clade. Our results revealed its cellular dimensions and details of its intracellular organization. Frozen-hydrated cells, which were preserved in a life-like state, had an average cell volume (enclosed by the outer membrane) of 0.037 ± 0.011 μm3. Strikingly, the periplasmic space occupied ~20% to 50% of the total cell volume in log-phase cells and ~50% to 70% in stationary-phase cells. The nucleoid occupied the convex side of the crescent-shaped cells and the ribosomes predominantly occupied the concave side, at a relatively high concentration of 10,000 to 12,000 ribosomes/μm3. Outer membrane pore complexes, likely composed of PilQ, were frequently observed in both log-phase and stationary-phase cells. Long filaments, most likely type IV pili, were found on dividing cells. The physical dimensions, intracellular organization, and morphological changes throughout the life cycle of "Ca. Pelagibacter ubique" provide structural insights into the functional adaptions of these oligotrophic ultramicrobacteria to their habitat.
AB - SAR11 bacteria are small, heterotrophic, marine alphaproteobacteria found throughout the oceans. They thrive at the low nutrient concentrations typical of open ocean conditions, although the adaptations required for life under those conditions are not well understood. To illuminate this issue, we used cryo-electron tomography to study "Candidatus Pelagibacter ubique" strain HTCC1062, a member of the SAR11 clade. Our results revealed its cellular dimensions and details of its intracellular organization. Frozen-hydrated cells, which were preserved in a life-like state, had an average cell volume (enclosed by the outer membrane) of 0.037 ± 0.011 μm3. Strikingly, the periplasmic space occupied ~20% to 50% of the total cell volume in log-phase cells and ~50% to 70% in stationary-phase cells. The nucleoid occupied the convex side of the crescent-shaped cells and the ribosomes predominantly occupied the concave side, at a relatively high concentration of 10,000 to 12,000 ribosomes/μm3. Outer membrane pore complexes, likely composed of PilQ, were frequently observed in both log-phase and stationary-phase cells. Long filaments, most likely type IV pili, were found on dividing cells. The physical dimensions, intracellular organization, and morphological changes throughout the life cycle of "Ca. Pelagibacter ubique" provide structural insights into the functional adaptions of these oligotrophic ultramicrobacteria to their habitat.
KW - Cryo-electron tomography
KW - PilQ
KW - SAR11
KW - Type IV pili
KW - Ultramicrobacteria
UR - http://www.scopus.com/inward/record.url?scp=85010223128&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85010223128&partnerID=8YFLogxK
U2 - 10.1128/AEM.02807-16
DO - 10.1128/AEM.02807-16
M3 - Article
VL - 83
JO - Applied and Environmental Microbiology
JF - Applied and Environmental Microbiology
SN - 0099-2240
IS - 3
M1 - e02807-16
ER -