title: Cellulose accumulation and a cellulose synthase gene are responsible for cell aggregation in the cyanobacterium Thermosynechococcus vulcanus RKN.
abstract: A thermophilic cyanobacterium, Thermosynechococcus vulcanus RKN, exhibits cell aggregation under low temperature illuminated conditions as a means of physiological acclimation to avoid excess light stress. The cell aggregation was dispersed with cellulase treatment. We developed a method to quantify small amounts of cellulose by partial cellulose purification followed by quantitation of liberated glucose by cellulase. Under low temperature illuminated light conditions, cellulose accumulation was induced approximately 2-fold, to 10 μg (4 × 10(9) cells)(-1), and slightly preceded aggregation. Based on sequence similarity, three candidate genes for cellulose synthase (Tvtll0007, Tvtlr1795 and Tvtlr1930-33) were cloned from T. vulcanus. Gene disruption analysis showed that only Tvtll0007 was responsible for both the light- and low temperature-induced cell aggregation and the induction of cellulose accumulation. Gene expression analysis suggested that the low temperature illuminated conditions quickly induced expression of Tvtlr1795 and Tvtlr1930-33, while the induction of Tvtll0007 was slow. These results suggest that Tvtll0007 encodes a functional cellulose synthase whose activity may not be regulated at the transcriptional level.
authors.affiliation: Department of Life Sciences (Biology), Graduate School of Arts and Science, University of Tokyo, Tokyo, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kawano
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Saotome
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Ochiai
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Katayama
authors.forename: Rei
authors.initials: R
authors.lastname: Narikawa
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ikeuchi
mesh_terms: D000064:Acclimatization; D002480:Cellulase / Q000378:metabolism; D002482:Cellulose / Q000032:analysis / Q000378:metabolism*; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000235:genetics / Q000254:growth & development*; D004269:DNA, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005947:Glucose / Q000032:analysis / Q000378:metabolism; D005964:Glucosyltransferases / Q000235:genetics*; D008027:Light; D013696:Temperature; D014158:Transcription, Genetic
chemical_list: D004269:DNA, Bacterial; D002482:Cellulose; D005964:Glucosyltransferases; C478648:cellulose synthase; D002480:Cellulase; D005947:Glucose