The role of a gene cluster for trehalose metabolism in dehydration tolerance of the filamentous cyanobacterium Anabaena sp. PCC 7120.
Expression of the genes for trehalose synthesis (mts and mth, encoding maltooligosyl trehalose synthase and hydrolase) and trehalose hydrolysis (treH) in Anabaena sp. PCC 7120 was up-regulated markedly upon dehydration. However, the amount of trehalose accumulated during dehydration was small, whereas a large amount of sucrose was accumulated. Northern blotting analysis revealed that these genes were transcribed as an operon. Gene disruption of mth resulted in a decrease in the trehalose level and in tolerance during dehydration. In contrast, gene disruption of treH resulted in an increase in both the amount of trehalose and tolerance. These results suggest that trehalose is important for the dehydration tolerance of this cyanobacterium. The amount of trehalose accumulated during dehydration was small, corresponding to 0.05-0.1 % of dry weight, suggesting that trehalose did not stabilize proteins and membranes directly during dehydration. To reveal the role of trehalose, the expression profiles of the wild-type strain and gene disruptants during dehydration were compared by using oligomeric DNA microarray. It was found that the expression of two genes, one of which encodes a cofactor of a chaperone DnaK, correlated with trehalose content, suggesting that a chaperone system induced by trehalose is important for the dehydration tolerance of Anabaena sp. PCC 7120.
Department of Life Sciences (Biology), University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902, Japan.|Department of Molecular Biology, Faculty of Science, Saitama University, 255 Shimo-Ohkubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan.
Akiyoshi
A
Higo
Department of Plant Functional Genomics, Life Science Research Center, Mie University, 1577 Kurimamachiya-cho, Tsu City, Mie 514-8507, Japan.
Hiroshi
H
Katoh
Department of Life Sciences, Showa Women's University, 1-7 Taishido, Setagaya, Tokyo 154-8533, Japan.
Kazuko
K
Ohmori
Department of Life Sciences (Biology), University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902, Japan.
Masahiko
M
Ikeuchi
Department of Molecular Biology, Faculty of Science, Saitama University, 255 Shimo-Ohkubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan.
Masayuki
M
Ohmori
D000222:Adaptation, Physiological / Q000235:genetics; D017033:Anabaena / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins; D015152:Blotting, Northern; D003681:Dehydration; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005959:Glucosidases / Q000235:genetics; D005964:Glucosyltransferases / Q000235:genetics; D018832:Molecular Chaperones / Q000235:genetics / Q000502:physiology; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D020411:Oligonucleotide Array Sequence Analysis; D012329:RNA, Bacterial / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D013395:Sucrose / Q000378:metabolism; D014158:Transcription, Genetic; D014199:Trehalose / Q000378:metabolism*
D001426:Bacterial Proteins; D018832:Molecular Chaperones; D012329:RNA, Bacterial; D012333:RNA, Messenger; D013395:Sucrose; D014199:Trehalose; D005964:Glucosyltransferases; C099084:maltooligosyl trehalose synthase; D005959:Glucosidases; C099156:maltooligosyl trehalose trehalohydrolase