Title

Description of Anti-Sinking Pilus Subunits in Picocyanobacteria

Date

11-8-2021 2:15 PM

Abstract

The picocyanobacteria are the dominant photosynthesizers throughout the world’s nutrient-poor open oceans. They not only form the base of the food chain, but also play a crucial role in carbon cycling on a global scale. Their success in harsh environments is due in part to the diversity of ecotypes - subspecies that have adapted to light and nutrient environments specific to a specific strata of the water column. The mechanism of ecotype localization is somewhat mysterious given that many of these cells are non-motile. The nonmotile Prochlorococcus sp. MIT9313 and its close relative Synechococcus sp. WH7803 can delay their sinking by producing large numbers of type 4 pili (T4P) when growth conditions are favorable. An abundance of these filaments on the cell surface increases the cell’s drag and slows its rate of sinking, suggesting a novel use of the structure to maintain depth. However, it is unknown whether anti-sinking pili production is conserved in the lower branches of Prochlorococcus or more broadly throughout the order Synechococcales. Here a phylogenetic tree of T4P subunit pilA is mapped to identify the conservation of domains associated with anti-sinking activity. 3D protein models are constructed for pilA from Prochlorococcus sp. MIT9313 and Synechococcus sp. WH7803 to identify common structural features. A gene network is constructed from protein-protein interaction data to uncover regulatory motifs that may distinguish between anti-sinking and conventional types of T4P.

Biographies

Max Wrubel, Biology

Hi, my name is Max and I’m pursuing a B.S. in biology at Portland State University. I’m a part of the Blue Water microbial oceanography lab at PSU’s Center for Life in Extreme Environments. I’m interested in the ecology of open-ocean microbes, and their roles in the global carbon cycle. Using the explosion of data produced by next-generation genetic sequencing technology, I believe microbial ecology will be key to addressing issues of human and environmental health in our future. As a Lester Newman Research Scholar, I used network analysis of gene expression in the ecologically critical photosynthetic marine bacterium Prochlorococcus. I merged data sets from studies published by others to connect genes to the cells’ response to environmental stress, and to improve our understanding of their gene regulation. I’m currently a McNair Scholar, continuing this work with a focus on how Prochlorococcus is able to control its depth for optimal sun exposure despite the upwellings and downwellings of the open ocean waters. I plan to deepen my studies of complex biological systems through a masters of science in computational biology before pursuing a Ph.D.

Dr. Anne Thompson, Faculty Mentor, Department of Biology

Anne Thompson is a Research Assistant Professor in the Biology Department at Portland State University. Thompson received her Ph.D. from the MIT- Woods Hole Oceanographic Institution Joint Program in Biological Oceanography and has held positions at UC Santa Cruz, BD Biosciences, and the Institute for Systems Biology prior to PSU. Thompson’s work illuminates the ecology of microorganisms in the Earth’s vast open oceans and how they contribute to energy and carbon flow on our planet.

Disciplines

Biology

Persistent Identifier

https://archives.pdx.edu/ds/psu/36205

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Aug 11th, 2:15 PM

Description of Anti-Sinking Pilus Subunits in Picocyanobacteria

The picocyanobacteria are the dominant photosynthesizers throughout the world’s nutrient-poor open oceans. They not only form the base of the food chain, but also play a crucial role in carbon cycling on a global scale. Their success in harsh environments is due in part to the diversity of ecotypes - subspecies that have adapted to light and nutrient environments specific to a specific strata of the water column. The mechanism of ecotype localization is somewhat mysterious given that many of these cells are non-motile. The nonmotile Prochlorococcus sp. MIT9313 and its close relative Synechococcus sp. WH7803 can delay their sinking by producing large numbers of type 4 pili (T4P) when growth conditions are favorable. An abundance of these filaments on the cell surface increases the cell’s drag and slows its rate of sinking, suggesting a novel use of the structure to maintain depth. However, it is unknown whether anti-sinking pili production is conserved in the lower branches of Prochlorococcus or more broadly throughout the order Synechococcales. Here a phylogenetic tree of T4P subunit pilA is mapped to identify the conservation of domains associated with anti-sinking activity. 3D protein models are constructed for pilA from Prochlorococcus sp. MIT9313 and Synechococcus sp. WH7803 to identify common structural features. A gene network is constructed from protein-protein interaction data to uncover regulatory motifs that may distinguish between anti-sinking and conventional types of T4P.