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Environ Microbiol. 2017 Jul;19(7):2862-2872. doi: 10.1111/1462-2920.13814. Epub 2017 Jul 13.

Type 4 pili are dispensable for biofilm development in the cyanobacterium Synechococcus elongatus.

Author information

1
The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 5290002 Israel.
2
Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
3
Weizmann Institute of Science, Electron Microscopy Unit, Rehovot, 7610001 Israel.
4
The Department of Desalination & Water Treatment, Zuckerberg Institute for Water Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Be'er Sheva 84990, Israel.

Abstract

The hair-like cell appendages denoted as type IV pili are crucial for biofilm formation in diverse eubacteria. The protein complex responsible for type IV pilus assembly is homologous with the type II protein secretion complex. In the cyanobacterium Synechococcus elongatus PCC 7942, the gene Synpcc7942_2071 encodes an ATPase homologue of type II/type IV systems. Here, we report that inactivation of Synpcc7942_2071 strongly affected the suite of proteins present in the extracellular milieu (exo-proteome) and eliminated pili observable by electron microscopy. These results support a role for this gene product in protein secretion as well as in pili formation. As we previously reported, inactivation of Synpcc7942_2071 enables biofilm formation and suppresses the planktonic growth of S. elongatus. Thus, pili are dispensable for biofilm development in this cyanobacterium, in contrast to their biofilm-promoting function in type IV pili-producing heterotrophic bacteria. Nevertheless, pili removal is not required for biofilm formation as evident by a piliated mutant of S. elongatus that develops biofilms. We show that adhesion and timing of biofilm development differ between the piliated and non-piliated strains. The study demonstrates key differences in the process of biofilm formation between cyanobacteria and well-studied type IV pili-producing heterotrophic bacteria.

PMID:
28585390
DOI:
10.1111/1462-2920.13814
[Indexed for MEDLINE]

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