AUTHOR=Gardiner Melissa , Hoke David E. , Egan Suhelen 

TITLE=An ortholog of the Leptospira interrogans lipoprotein LipL32 aids in the colonization of Pseudoalteromonas tunicata to host surfaces

JOURNAL=Frontiers in Microbiology

VOLUME=5

YEAR=2014

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2014.00323

DOI=10.3389/fmicb.2014.00323

ISSN=1664-302X

ABSTRACT=<p>The bacterium <italic>Pseudoalteromonas tunicata</italic> is a common surface colonizer of marine eukaryotes, including the macroalga <italic>Ulva australis.</italic>Genomic analysis of <italic>P. tunicata</italic> identified genes potentially involved in surface colonization, including genes with homology to bacterial virulence factors that mediate attachment. Of particular interest is the presence of a gene, designated <italic>ptlL32</italic>, encoding an ortholog to the <italic>Leptospira</italic> lipoprotein LipL32, which has been shown to facilitate the interaction of <italic>Leptospira</italic> sp. with host extracellular matrix (ECM) structures and is thought to be an important virulence trait for pathogenic <italic>Leptospira</italic>. To investigate the role of PtlL32 in the colonization by <italic>P. tunicata</italic> we constructed and characterized a Δ<italic>ptlL32</italic> mutant strain. Whilst <italic>P. tunicata</italic> Δ<italic>ptlL32</italic> bound to an abiotic surface with the same capacity as the wild type strain, it had a marked effect on the ability of <italic>P. tunicata</italic> to bind to ECM, suggesting a specific role in attachment to biological surfaces. Loss of PtlL32 also significantly reduced the capacity for <italic>P. tunciata</italic> to colonize the host algal surface demonstrating a clear role for this protein as a host-colonization factor. PtlL32 appears to have a patchy distribution across specific groups of environmental bacteria and phylogenetic analysis of PtlL32 orthologous proteins from non-<italic>Leptospira</italic> species suggests it may have been acquired via horizontal gene transfer between distantly related lineages. This study provides the first evidence for an attachment function for a LipL32-like protein outside the <italic>Leptospira</italic> and thereby contributes to the understanding of host colonization in ecologically distinct bacterial species.</p>