Extensive epigenetic modification with large-scale chromosomal and plasmid recombination characterise the Legionella longbeachae serogroup 1 genome
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Date
2022-04-06
Open Access Location
Journal Title
Journal ISSN
Volume Title
Publisher
Springer Nature Limited
Rights
(c) 2022 The Author/s
CC BY 4.0
CC BY 4.0
Abstract
Legionella longbeachae is an environmental bacterium that is the most clinically significant Legionella species in New Zealand (NZ), causing around two-thirds of all notified cases of Legionnaires’ disease. Here we report the sequencing and analysis of the geo-temporal genetic diversity of 54 L. longbeachae serogroup 1 (sg1) clinical isolates, derived from cases from around NZ over a 22-year period, including one complete genome and its associated methylome. The 54 sg1 isolates belonged to two main clades that last shared a common ancestor between 95 BCE and 1694 CE. There was diversity at the genome-structural level, with large-scale arrangements occurring in some regions of the chromosome and evidence of extensive chromosomal and plasmid recombination. This includes the presence of plasmids derived from recombination and horizontal gene transfer between various Legionella species, indicating there has been both intra- and inter-species gene flow. However, because similar plasmids were found among isolates within each clade, plasmid recombination events may pre-empt the emergence of new L. longbeachae strains. Our complete NZ reference genome consisted of a 4.1 Mb chromosome and a 108 kb plasmid. The genome was highly methylated with two known epigenetic modifications, m4C and m6A, occurring in particular sequence motifs within the genome.
Description
Keywords
Microbial genetics, Pathogens
Citation
Slow S, Anderson T, Murdoch DR, Bloomfield S, Winter D, Biggs PJ. (2020). Characterising the methylome of <i>Legionella longbeachae</i> serogroup 1 clinical isolates and assessing geo-temporal genetic diversity. Scientific Reports. 12.