title: An AbrB-like protein might be involved in the regulation of cylindrospermopsin production by Aphanizomenon ovalisporum.
abstract: Certain filamentous cyanobacteria, including Aphanizomenon ovalisporum, are potentially toxic owing to the formation of the hepatotoxin cylindrospermopsin. We previously identified a gene cluster in A. ovalisporum likely to be involved in cylindrospermopsin biosynthesis, including amidinotransferase (aoaA) and polyketide-synthase (aoaC), transcribed on the reverse strands. Analysis of the genomic region between aoaA and aoaC identified two transcription start points for each of these genes, differentially expressed under nitrogen and light stress conditions. The transcript abundances of these genes and the cylindrospermopsin level were both affected by nitrogen availability and light intensity. Gel shift assays and DNA affinity columns isolated a protein that specifically binds to a 150 bp DNA fragment from the region between aoaA and aoaC, and MS/MS analyses identified similarity to AbrB in other cyanobacteria and in Bacillus sp. Comparison of the native AbrB isolated from A. ovalisporum with that obtained after cloning and overexpression of abrB in Escherichia coli identified specific post-translational modifications in the native cyanobacterial protein. These modifications, which are missing in the protein expressed in E. coli, include N-acetylation and methylation of specific residues. We discuss the possible role of these modifications in the regulation of cylindrospermopsin production in Aphanizomenon.
authors: Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors: Gali
authors: G
authors: Shalev-Malul
authors: Judy
authors: J
authors: Lieman-Hurwitz
authors: Yehudith
authors: Y
authors: Viner-Mozzini
authors: Assaf
authors: A
authors: Sukenik
authors: Ariel
authors: A
authors: Gaathon
authors: Mario
authors: M
authors: Lebendiker
authors: Aaron
authors: A
authors: Kaplan
mesh_terms: D000470:Alkaloids; D000579:Amidinotransferases / Q000235:genetics; D046890:Aphanizomenon / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D016680:Genome, Bacterial; D008027:Light; D009584:Nitrogen; D048630:Polyketide Synthases / Q000235:genetics; D011499:Protein Processing, Post-Translational; D014498:Uracil / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D000470:Alkaloids; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; C089595:cylindrospermopsin; D014498:Uracil; D048630:Polyketide Synthases; D000579:Amidinotransferases; D009584:Nitrogen