The UK cellular microbiology network: Exploring the host‐bacterial interface

Abstract The UK Cellular Microbiology Network held its inaugural conference in February 2019. This stimulating day of scientific exchange will be the first of many, its organisers hope.


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In an era of vast conferences with thousands of participants, where poster sessions may be held in halls the size of aircraft carriers, scientists often find solace in smaller meetings. These allow better opportunities for personal connections, but also permit focusing on topics that seldom get much airplay in modern, multi-stream mega-symposia.
They can also serve to create and consolidate valuable regional or national networks.
The cellular microbiology of bacterial pathogens is one such niche topic within the greater umbrella of microbiology, with its exotic array of viral, fungal, and bacterial microbes jockeying for position, alongside the competing interests of the immunological response. In an era of increasing antibiotic resistance, furthering our understanding of how prokaryotes interact with their host cells, and developing novel ways to intervene, has never been more important. Despite this imperative, conferences focusing on this topic are rare, and its researchers are often situated in academic departments with different foci, meaning that they can sometimes feel like isolated members of a diaspora and often struggle to meet valuable collaborators.
For this reason, we decided to organise an annual forum in the United Kingdom-dubbed "The UK Cellular Microbiology Network"devoted to the cell biology of host-bacterial interactions. Despite the national emphasis, we were keen to welcome any of our geographical neighbours who wished to attend. We wanted to focus specifically on how bacterial pathogens subvert host cellular processes and how the host cell responds. In creating an engaging, affordable, and informal meeting showcasing the work of early-career researchers, we hoped to encourage the forging of useful collaborations and crossfertilisation of diverse expertise and experiences about host cell biology across the wide variety of bacterial pathogens under study.
Our inaugural one-day meeting was held at London's Francis Crick Institute on 11 February 2019 ( Figure 1). About 140 researchers from gathered in Central London on a cold, sunny day, along with representatives of our generous sponsors, including the Microbiological Society, the Biochemical Society, the British Society for Cell Biology, the Journal of Cell Science, Perkin Elmer, Zeiss-and this journal, Cellular Microbiology. In addition to the programme of talks, we also had a vibrant poster session and ended the evening with drinks, nibbles, and serious networking in the Crick's lovely gallery space.
The meeting kicked off with the first of our two keynote speakers, Carmen Buchrieser from the Institut Pasteur in Paris. Challenging her audience with the idea that Legionella is "the best cell biologist," she went on to describe some of her team's groundbreaking work exploiting this bacterium to understand host cell function. In the first half of her talk, she demonstrated how the bacterium, once phagocytosed into lysosomes, secretes around 300 proteins to make a replicative vacuole. In the process, it hijacks various host cytoskeletal regulators to fragment mitochondria. This act of sabotage seems to set up a "Warburg-like" environment of high oxygen consumption and high glycolysis that helps the microbes to replicate. Her team identified a T4SS-secreted effector of Legionella that is implicated in inducing this mitochondrial fragmentation. Most interestingly, this effector encodes protein domains normally only found in eukaryotes.
She then showed that such eukaryotic domains are a specific feature of the Legionella genomes as she described an exciting comparative functional analysis of 80 Legionella genomes spanning 58 species, many of which have acquired the ability to infect eukaryotic cells independently. Indeed, in the process, these species have co-opted a large number of host genes in order to subvert their hosts, courtesy of the highly conserved type IV secretion system (T4SS).
Secretion-a popular virulence strategy amongst prokaryotes-fea-