Role of PatS and cell type on the heterocyst spacing pattern in a filamentous branching cyanobacterium

• Published in: FEMS microbiology letters Vol. 364; no. 15
• Main Authors: Antonaru, Laura A., Nürnberg, Dennis J.
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 15.08.2017
• Subjects: Anabaena; Anabaena - physiology; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bioinformatics; Cell culture; Cell differentiation; Culture Media; Cyanobacteria; Cyanobacteria - genetics; Cyanobacteria - metabolism; Deprivation; Differentiation (biology); Gene Expression Regulation, Bacterial; Heterocysts; Mastigocladus laminosus; Microbiology; Nitrogen - metabolism; Nitrogen Fixation; Nostoc; Phenotypes; Physiology & Biochemistry; Research Letter; Trichomes; multicellularity; cell differentiation; PatS; cyanobacteria; heterocyst spacing pattern; nitrogen fixation; Stigonematales
• ISSN: 1574-6968; 0378-1097; 1574-6968
• DOI: 10.1093/femsle/fnx154

Abstract Cell differentiation is one of the marks of multicellular organisms. Terminally specialised nitrogen-fixing cells, termed heterocysts, evolved in filamentous cyanobacteria more than 2 Gya. The development of their spacing pattern has been thoroughly investigated in model organisms such as Anabaena sp. PCC 7120. This paper focuses on the more complex, branching cyanobacterium Mastigocladus laminosus (Stigonematales). Contrary to what has been previously published, a heterocyst spacing pattern is present in M. laminosus but it varies with the age of the culture and the morphology of the cells. Heterocysts in young, narrow trichomes were more widely spaced (∼14.8 cells) than those in old, wide trichomes (∼9.4 cells). Biochemical and transgenic experiments reveal that the heterocyst spacing pattern is affected by the heterocyst inhibitor PatS. Addition of the pentapeptide RGSGR (PatS-5) to the growth medium and overexpression of patS from Anabaena sp. PCC 7120 in M. laminosus resulted in the loss of heterocyst differentiation under nitrogen deprivation. Bioinformatics investigations indicated that putative PatS sequences within cyanobacteria are highly diverse, and fall into two main clades. Both are present in most branching cyanobacteria. Despite its more complex, branching phenotype, M. laminosus appears to use a PatS-based pathway for heterocyst differentiation, a property shared by Anabaena/Nostoc. In the filamentous branching cyanobacterium Mastigocladus laminosus, the heterocyst spacing pattern is regular but cell-type specific, and depends on PatS, the protein that controls cell differentiation.