Dresden International Graduate School for Interdisciplinary Life Sciences

Diatoms are unicellular microalgae surrounded by intricate silica-based cell walls and major primary producers in aquatic ecosystems. Benthic diatoms have evolved a remarkable ability to attach to surfaces and form biofilms by secreting adhesive materials. These biofilms consist of communities of cells embedded within a hydrated extracellular matrix containing proteins, polysaccharides, and nucleic acids. This matrix enables diatoms to attach to surfaces, interact with their environment, and survive under challenging conditions.

Despite advances in diatom genome sequencing, we still know surprisingly little about the molecular mechanisms underlying diatom adhesion and biofilm formation. Recent research has identified a novel family of adhesive proteins, called Trailins, found in the primary adhesive layer (PAL) secreted by benthic diatoms. Trailins are highly modular proteins with a characteristic “beads-on-a-string” architecture, in which individual domains likely perform different structural or functional roles. Interestingly, Trailins appear to have been acquired from bacteria through horizontal gene transfer (HGT). One domain exhibits structural similarity to bacterial ice-binding proteins despite little or no detectable sequence similarity, suggesting that structural homology can reveal evolutionary relationships missed by conventional sequence-based approaches.

This project aims to uncover the molecular basis of diatom adhesion and biofilm formation by identifying and characterizing previously unrecognized adhesive protein domains. We will employ remote homology detection approaches to identify evolutionarily distant homologs that are difficult to detect using conventional sequence comparisons. These approaches will be combined with topology-based screening and specialized computational algorithms to search large genomic databases for structurally and functionally related protein domains. Promising candidates will then be experimentally characterized using heterologous expression, adhesion assays, and mechanical measurements to determine their structural and functional properties.

By integrating computational discovery with biochemical and biophysical characterization, this project will establish links between protein structure, molecular function, and evolutionary history. Ultimately, it will provide insight into how diatoms have evolved specialized adhesive mechanisms and how these adaptations enable them to colonize surfaces, form biofilms, and thrive in diverse aquatic environments.