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Cd-induced cytosolic proteome changes in the cyanobacterium Anabaena sp. PCC7120 are mediated by LexA as one of the regulatory proteins. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2023; 1871:140902. [PMID: 36716944 DOI: 10.1016/j.bbapap.2023.140902] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 01/10/2023] [Accepted: 01/23/2023] [Indexed: 01/28/2023]
Abstract
LexA, a well-characterized transcriptional repressor of SOS genes in heterotrophic bacteria, has been shown to regulate diverse genes in cyanobacteria. An earlier study showed that LexA overexpression in a cyanobacterium, Anabaena sp. PCC7120 reduces its tolerance to Cd stress. This was later shown to be due to modulation of photosynthetic redox poising by LexA under Cd stress. However, due to the global regulatory nature of LexA and the prior prediction of AnLexA-box in a few heavy metal-responsive genes, we speculated that LexA has a broad role in Cd tolerance, with regulation over a variety of Cd stress-responsive genes in addition to photosynthetic genes. Thus, to further expand the knowledge on the regulatory role of LexA in Cd stress tolerance, a cytosolic proteome profiling of Anabaena constitutively overexpressing LexA upon Cd stress was performed. The proteomic study revealed 25 differentially accumulated proteins (DAPs) in response to the combined effect of LexA overexpression and Cd stress, and the other 11 DAPs exclusively in response to either LexA overexpression or Cd stress. The 36 identified proteins were related with a variety of functions, including photosynthesis, C-metabolism, antioxidants, protein turnover, post-transcriptional modifications, and a few unknown and hypothetical proteins. The regulation of LexA on corresponding genes, and six previously reported Cd efflux transporters, was further validated by the presence of AnLexA-boxes, transcript, and/or promoter analyses. In a nutshell, this study identifies the regulation of Anabaena LexA on several Cd stress-responsive genes of various functions, hence expanding the regulatory role of LexA under Cd stress.
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Zoumplis A, Kolody B, Kaul D, Zheng H, Venepally P, McKnight DM, Takacs-Vesbach C, DeVries A, Allen AE. Impact of meltwater flow intensity on the spatiotemporal heterogeneity of microbial mats in the McMurdo Dry Valleys, Antarctica. ISME COMMUNICATIONS 2023; 3:3. [PMID: 36690784 PMCID: PMC9870883 DOI: 10.1038/s43705-022-00202-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 11/13/2022] [Accepted: 11/16/2022] [Indexed: 01/24/2023]
Abstract
The meltwater streams of the McMurdo Dry Valleys are hot spots of biological diversity in the climate-sensitive polar desert landscape. Microbial mats, largely comprised of cyanobacteria, dominate the streams which flow for a brief window of time (~10 weeks) over the austral summer. These communities, critical to nutrient and carbon cycling, display previously uncharacterized patterns of rapid destabilization and recovery upon exposure to variable and physiologically detrimental conditions. Here, we characterize changes in biodiversity, transcriptional responses and activity of microbial mats in response to hydrological disturbance over spatiotemporal gradients. While diverse metabolic strategies persist between marginal mats and main channel mats, data collected from 4 time points during the austral summer revealed a homogenization of the mat communities during the mid-season peak meltwater flow, directly influencing the biogeochemical roles of this stream ecosystem. Gene expression pattern analyses identified strong functional sensitivities of nitrogen-fixing marginal mats to changes in hydrological activities. Stress response markers detailed the environmental challenges of each microhabitat and the molecular mechanisms underpinning survival in a polar desert ecosystem at the forefront of climate change. At mid and end points in the flow cycle, mobile genetic elements were upregulated across all mat types indicating high degrees of genome evolvability and transcriptional synchronies. Additionally, we identified novel antifreeze activity in the stream microbial mats indicating the presence of ice-binding proteins (IBPs). Cumulatively, these data provide a new view of active intra-stream diversity, biotic interactions and alterations in ecosystem function over a high-flow hydrological regime.
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Affiliation(s)
- A Zoumplis
- Scripps Institution of Oceanography, University of California, San Diego, CA, USA
- Microbial and Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA, USA
| | - B Kolody
- Earth and Planetary Science, University of California, Berkeley, Berkeley, CA, USA
| | - D Kaul
- Microbial and Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA, USA
| | - H Zheng
- Microbial and Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA, USA
| | - P Venepally
- Microbial and Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA, USA
| | - D M McKnight
- Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA
| | - C Takacs-Vesbach
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - A DeVries
- Evolution, Ecology and Behavior, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - A E Allen
- Scripps Institution of Oceanography, University of California, San Diego, CA, USA.
- Microbial and Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA, USA.
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