TY - JOUR
T1 - An AbrB-like protein might be involved in the regulation of cylindrospermopsin production by Aphanizomenon ovalisporum
AU - Shalev-Malul, Gali
AU - Lieman-Hurwitz, Judy
AU - Viner-Mozzini, Yehudith
AU - Sukenik, Assaf
AU - Gaathon, Ariel
AU - Lebendiker, Mario
AU - Kaplan, Aaron
PY - 2008/4
Y1 - 2008/4
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=40949115129&partnerID=8YFLogxK
U2 - 10.1111/j.1462-2920.2007.01519.x
DO - 10.1111/j.1462-2920.2007.01519.x
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C2 - 18093160
AN - SCOPUS:40949115129
SN - 1462-2912
VL - 10
SP - 988
EP - 999
JO - Environmental Microbiology
JF - Environmental Microbiology
IS - 4
ER -