HesF, an exoprotein required for filament adhesion and aggregation in Anabaena sp PCC 7120

• Type: Article in International Scientific Journal
• Date: 2015

Authors

Paulo Oliveira (Author) Other; Filipe Pinto (Author) Other; Catarina C Pacheco (Author) Other; Rita Mota (Author) Other; Paula Tamagnini (Author) FCUP

Journal

Title: Environmental Microbiology

Vol. 17

Pages: 1631-1648

ISSN: 1462-2912

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 23 Citations

Scopus - 24 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

CORDIS: Natural sciences > Biological sciences > Biology > Microbiology

Other information

Authenticus ID: P-00A-CHC

DOI: 10.1111/1462-2920.12600

Abstract (EN): Here, we report on the identification and characterization of a protein (Alr0267) named HesF, found in the extracellular milieu of Anabaena sp. PCC 7120 grown diazotrophically. hesF was found to be highly upregulated upon transition from non-nitrogen-fixing to nitrogen-fixing conditions, and the highest transcript levels were detected towards the end of the heterocyst differentiation process. The hesF promoter drives transcription of the gene in heterocysts only, and both NtcA and HetR are essential for the gene's in vivo activation. An examination of HesF's translocation showed that the secretion system is neither heterocyst-specific nor dependent on nitrogen-fixing conditions. Furthermore, HesF was found to be a type I secretion system substrate, since an HgdD mutant failed to secrete HesF. Several analyses revealed that a HesF minus mutant strain lacks the heterocyst-specific polysaccharide fibrous layer, accumulates high amounts of polysaccharides in the medium and that HesF is essential for the typical aggregation phenotype in diazotrophic conditions. Thus, we propose that HesF is a carbohydrate-binding exoprotein that plays a role in maintaining the heterocyst cell wall structure. A combination of and possibly interaction between HesF and heterocyst-specific polysaccharides seems to be responsible for filament adhesion and culture aggregation in heterocyst-forming cyanobacteria.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 18