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Constitutive expression of a small heat‐shock protein confers cellular thermotolerance and thermal protection to the photosynthetic apparatus in cyanobacteria
Author(s) -
Nakamoto Hitoshi,
Suzuki Nobuaki,
Roy Sanjit Kumer
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)02097-4
Subject(s) - phycobilisome , heat shock protein , synechococcus , biology , groes , photosystem ii , microbiology and biotechnology , photosynthesis , cyanobacteria , biophysics , gene , botany , chemistry , groel , biochemistry , genetics , bacteria , escherichia coli
The role of a small heat‐shock protein (Hsp) in the acquisition of thermotolerance in cyanobacteria was investigated. Synechococcus sp. PCC 7942 was transformed with an expression vector carrying the coding sequence of the hspA gene encoding a small heat‐shock protein from Synechococcus vulcanus under the control of the tac promoter. The transformant which was shown to constitutively express HspA displayed improved viability compared with the reference strain upon transfer from 30 to 50°C in the light. When the heat shock was given in darkness, the survival rate in the reference strain increased greatly, approaching a level similar to that for the HspA expressing strain after heat shock in the light. Expression of HspA increased thermal resistance of photosystem II (PS II) and protected phycocyanin from heat‐induced photobleaching. Our results are indicative of a central role for HspA in amelioration of the harmful effect of light during heat stress and identified the possible sites of action of the small Hsp in vivo to be the PS II complex and the light‐harvesting phycobilisomes.