Genetic characterization of the hmp locus, a chemotaxis‐like gene cluster that regulates hormogonium development and motility in Nostoc punctiforme

@article{Risser2014GeneticCO,
  title={Genetic characterization of the hmp locus, a chemotaxis‐like gene cluster that regulates hormogonium development and motility in Nostoc punctiforme},
  author={Douglas D. Risser and William Chew and John C. Meeks},
  journal={Molecular Microbiology},
  year={2014},
  volume={92}
}
Filamentous cyanobacteria are capable of gliding motility, but the mechanism of motility is not well defined. Here we present a detailed characterization of the hmp locus from Nostoc punctiforme, which encodes chemotaxis‐like proteins. Deletions of hmpB, C, D and E abolished differentiation of hormogonia under standard growth conditions, but, upon addition of a symbiotic partner exudate, the mutant strains differentiated hormogonium‐like filaments that lacked motility and failed to secrete… 
A partner‐switching regulatory system controls hormogonium development in the filamentous cyanobacterium Nostoc punctiforme
TLDR
Results support a model where HmpU and HmpW antagonistically regulate the phosphorylation state of HmpV, and subsequently, unphosphorylated HMPV positively regulates an undefined downstream target to affect hormogonium‐specific gene expression.
Dynamic localization of HmpF regulates type IV pilus activity and directional motility in the filamentous cyanobacterium Nostoc punctiforme
TLDR
Results are consistent with a model where direct interaction between HMPF and the T4P system activates pilus extension, the Hmp system facilitates coordinated polarity of HmpF to establish motility, and the Ptx system modulates Hmpf localization to initiate reversals in response to changes in light intensity.
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TLDR
A co‐occurrence analysis of Hps orthologs among cyanobacteria identified an extended set of putative Hps proteins comprising most components of a Wzx/Wzy‐type polysaccharide synthesis and export system, implying that HPS may be secreted through a more canonical pathway, rather than a T4P‐mediated mechanism.
Evidence that a modified type IV pilus‐like system powers gliding motility and polysaccharide secretion in filamentous cyanobacteria
TLDR
The theory that Hps and Pil proteins compose the JPC, a type IV pilus‐like nanomotor that drives motility and polysaccharide secretion in filamentous cyanobacteria, is supported.
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Results imply that O-GlcNAc protein modification regulates the accumulation of PilA via a posttranscriptional mechanism in developing hormogonia.
The hmp chemotaxis cluster regulates gliding in the filamentous cyanobacterium Nostoc punctiforme
TLDR
The hmp locus is revealed as an important regulator of gliding and highlights N. punctiforme as a model for understanding gliding motility in a complex multicellular bacterium.
Genetic Analysis Reveals the Identity of the Photoreceptor for Phototaxis in Hormogonium Filaments of Nostoc punctiforme
TLDR
N. punctiforme hormogonia are positively phototactic to white light over a wide range of intensities and are confirmed to be a basic chemotaxis-like signal transduction complex in cyanobacteriochrome species.
The Hybrid Histidine Kinase HrmK Is an Early-Acting Factor in the Hormogonium Gene Regulatory Network
TLDR
Results indicate that hrmK functions upstream of the sigma-factor cascade to initiate hormog onium development, likely by modulating the phosphorylation state of an unknown protein that may serve as the master regulator of hormogonium development in heterocyst-forming cyanobacteria.
The dgc2 gene encoding di-guanylate cyclase suppresses both motility and biofilm formation in the filamentous cyanobacterium Leptolyngbya boryana
Colony pattern formations of bacteria with motility manifest complicated morphological self-organization phenomena. Leptolyngbya boryana is the filamentous cyanobacterial species, which has been used
The primary transcriptome of hormogonia from a filamentous cyanobacterium defined by cappable-seq.
TLDR
The data presented provides new insights on sequence conservation within the -10 regions of both SigC- and SigF-dependent promoters, and demonstrates that SigJ and SigC coordinate complex co-regulation not only of hormogonium-specific genes at different loci, but within an individual operon.
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