GPCR Genes as Activators of Surface Colonization Pathways in a Model Marine Diatom.

Weiqi Fu,Alexandra Mystikou,Ashish Jaiswal,Kristos Baffour,Sigurdur Brynjolfsson,Kourosh Salehi-Ashtiani,Amnah Alzahmi,Bushra Dohai,David R Nelson,Sarah Daakour,Dina Al Khairy,James Weston,Amphun Chaiboonchoe,Mehar Sultana

doi:10.1016/j.isci.2020.101424

Weiqi Fu, Alexandra Mystikou + Show 12 more

Open Access

https://doi.org/10.1016/j.isci.2020.101424

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Abstract

SummarySurface colonization allows diatoms, a dominant group of phytoplankton in oceans, to adapt to harsh marine environments while mediating biofoulings to human-made underwater facilities. The regulatory pathways underlying diatom surface colonization, which involves morphotype switching in some species, remain mostly unknown. Here, we describe the identification of 61 signaling genes, including G-protein-coupled receptors (GPCRs) and protein kinases, which are differentially regulated during surface colonization in the model diatom species, Phaeodactylum tricornutum. We show that the transformation of P. tricornutum with constructs expressing individual GPCR genes induces cells to adopt the surface colonization morphology. P. tricornutum cells transformed to express GPCR1A display 30% more resistance to UV light exposure than their non-biofouling wild-type counterparts, consistent with increased silicification of cell walls associated with the oval biofouling morphotype. Our results provide a mechanistic definition of morphological shifts during surface colonization and identify candidate target proteins for the screening of eco-friendly, anti-biofouling molecules.

Highlights

Diatoms (Bacillariophyta) are the dominant group of microalgae in today’s oceans (Benoiston et al, 2017; Mock et al, 2017) and one of the most diverse and ecologically important clades of phytoplankton, contributing up to 20% of the global primary production (Bowler et al, 2008; Levitan et al, 2014; Vardi et al, 2008)
We demonstrate that engineering the strain to overexpress a G-protein-coupled receptors (GPCRs) gene is sufficient to shift the dominant morphotype from fusiform to oval cells during non-stress growth conditions
Genome-wide Transcriptome Analysis of Two Different Morphotype Cultures To identify transcriptional shift of cells between solid culture and liquid culture, we performed RNA sequencing (RNA-seq) on RNA isolated from the WT P. tricornutum strain Pt1 8.6F grown in liquid and on solid media under low light intensity of 30–50 mmol photons mÀ2 sÀ1

Summary

Introduction

Diatoms (Bacillariophyta) are the dominant group of microalgae in today’s oceans (Benoiston et al, 2017; Mock et al, 2017) and one of the most diverse and ecologically important clades of phytoplankton, contributing up to 20% of the global primary production (Bowler et al, 2008; Levitan et al, 2014; Vardi et al, 2008). Surface colonization and biofilm formation have substantial physiological advantages for microalgae in response to stress conditions and play important roles in microbial adaptation to fluctuations in marine environments (Dang and Lovell, 2016; Schaum, 2019). The diatom Phaeodactylum tricornutum, can grow in the absence of silicon and exists in different morphotypes such as fusiform, oval, and triradiate cell forms. Among these forms, only the oval cells make silicified frustules (De Martino et al, 2011; Lewin et al, 1958).

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