Title

Bioinformatics analyses of genes essential for motility in the filamentous cyanobacterium Nostoc punctiforme

Poster Number

31

Lead Author Major

Pre-Dentistry and Biological Sciences

Format

Poster Presentation

Faculty Mentor Name

Doug Risser

Faculty Mentor Department

Biological Sciences

Abstract/Artist Statement

The goal of this project is to identify the genes essential for motility in the filamentous cyanobacterium Nostoc punctiforme. N. punctiforme differentiates hormogonia, motile filaments which facilitate dispersal, the establishment of nitrogen-fixing symbioses with plants and fungi, and phototaxis. Both type IV pili and polysaccharide secretion have been suggested as propulsion mechanisms but the exact role each plays in hormogonium motility is unknown. As part of an ongoing project to identify the genes essential for motility in N. punctiforme we have performed a detailed analysis of the 125 genes previously identified as essential for motility using a transposon mutagenesis screen. Analyses include coordinate mapping of genes onto the N. punctiforme chromosome, assignment of genes to functional classes, transcriptional profiles of gene expression patterns during the course of hormogonium development and comparative genomics analyses to define the conservation pattern among cyanobacteria. The largest percentage of inactivated genes (40%) encode for conserved hypothetical proteins with unknown functions, followed by those characterized as core (25%), including several proteins related to cell envelope and polysaccharide synthesis, then adaptive genes (23%) including transcriptional regulators and signal transduction proteins, and finally transport (10%). Many of these genes were transcriptionally upregulated over the course of hormogonium development. Inactivated genes included those encoding homologs to the type IV pilus proteins PilB and PilN, as well as 8 different glycosyl transferases presumed to be involved in polysaccharide synthesis. Several genes are highly conserved in filamentous cyanobacteria, but poorly conserved in Synechocystis sp. PCC 6803, a model organism for motility of unicellular cyanobacteria. We conclude that gliding motility in filamentous cyanobacteria is most likely driven by a hybrid type IV pilus/polysaccharide secretion system and that hormogonium development and motility is governed by a complex network of signal transduction systems.

Location

DeRosa University Center, Ballroom

Start Date

25-4-2015 2:00 PM

End Date

25-4-2015 4:00 PM

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Apr 25th, 2:00 PM Apr 25th, 4:00 PM

Bioinformatics analyses of genes essential for motility in the filamentous cyanobacterium Nostoc punctiforme

DeRosa University Center, Ballroom

The goal of this project is to identify the genes essential for motility in the filamentous cyanobacterium Nostoc punctiforme. N. punctiforme differentiates hormogonia, motile filaments which facilitate dispersal, the establishment of nitrogen-fixing symbioses with plants and fungi, and phototaxis. Both type IV pili and polysaccharide secretion have been suggested as propulsion mechanisms but the exact role each plays in hormogonium motility is unknown. As part of an ongoing project to identify the genes essential for motility in N. punctiforme we have performed a detailed analysis of the 125 genes previously identified as essential for motility using a transposon mutagenesis screen. Analyses include coordinate mapping of genes onto the N. punctiforme chromosome, assignment of genes to functional classes, transcriptional profiles of gene expression patterns during the course of hormogonium development and comparative genomics analyses to define the conservation pattern among cyanobacteria. The largest percentage of inactivated genes (40%) encode for conserved hypothetical proteins with unknown functions, followed by those characterized as core (25%), including several proteins related to cell envelope and polysaccharide synthesis, then adaptive genes (23%) including transcriptional regulators and signal transduction proteins, and finally transport (10%). Many of these genes were transcriptionally upregulated over the course of hormogonium development. Inactivated genes included those encoding homologs to the type IV pilus proteins PilB and PilN, as well as 8 different glycosyl transferases presumed to be involved in polysaccharide synthesis. Several genes are highly conserved in filamentous cyanobacteria, but poorly conserved in Synechocystis sp. PCC 6803, a model organism for motility of unicellular cyanobacteria. We conclude that gliding motility in filamentous cyanobacteria is most likely driven by a hybrid type IV pilus/polysaccharide secretion system and that hormogonium development and motility is governed by a complex network of signal transduction systems.