|DUTTA, V - Envirologix|
|LEE, S - North Carolina State University|
|KATHARIOU, S - North Carolina State University|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/2/2015
Publication Date: 6/2/2015
Citation: Dutta, V., Ward, T.J., Lee, S., Kathariou, S. 2015. Diverse genomic location and sequence content of a Listeria monocytogenes chromosomal island harboring heavy metal resistance and other genes [abstract].
Technical Abstract: Listeria monocytogenes remains a major foodborne pathogen with three serotype 4b clonal groups (ECI, ECII, ECIa) repeatedly implicated in human listeriosis. For reasons that are unknown, many of these strains are also resistant to heavy metals, i.e. cadmium and arsenic. The acquisition and fitness impacts of heavy metal resistance genes remain poorly characterized. Here we investigated diversity in chromosomal location and sequence content of a large (35 kb) genomic island (LGI2) harboring numerous genes, including arsenic and cadmium resistance determinants. LGI2 was originally identified within the LmoF2365_2257 homolog in L. monocytogenes ScottA (serotype 4b, ECIa). Genomes of 10 arsenic-resistant strains (including serotype 4b and others) were sequenced, annotated, and LGI2 island determinants were localized. Strains included those with previous PCR and sequencing evidence for LGI2 being inserted in chromosomal locations other than the one identified in ScottA. Genome sequence data confirmed insertion of LGI2 in diverse chromosomal locations. In the majority (7/10) of strains, sequences within this island [i.e. arsenic and cadmium resistance determinants, conjugative gene transfer, anti-restriction, phage integration and pathogenicity] were intact with 99-100% nt identity to their counterparts in LGI2 of ScottA. In contrast, in one strain (serotype 1/2c, 3c) all island determinants exhibited sequence divergence from ScottA LGI2 with sequence identity ranging between 95-98% and with exceptionally high (86%) divergence in the cadmium resistance determinant. The remaining two strains (both serotype 4b) indicated remarkable divergence: only a portion of the island was detected with 81-91% nt identity to LGI2. Taken together, these data suggest active mobility and genetic diversification of LGI2 in L. monocytogenes. More work is needed to understand the significance of this island in shaping the adaptations and possibly the epidemiology of L. monocytogenes.