title: An RNA helicase, CrhR, regulates the low-temperature-inducible expression of heat-shock genes groES, groEL1 and groEL2 in Synechocystis sp. PCC 6803.
abstract: The crhR gene for RNA helicase, CrhR, was one of the most highly induced genes when the cyanobacterium Synechocystis sp. PCC 6803 was exposed to a downward shift in ambient temperature. Although CrhR may be involved in the acclimatization of cyanobacterial cells to low-temperature environments, its functional role during the acclimatization is not known. In the present study, we mutated the crhR gene by replacement with a spectinomycin-resistance gene cassette. The resultant DeltacrhR mutant exhibited a phenotype of slow growth at low temperatures. DNA microarray analysis of the genome-wide expression of genes, and Northern and Western blotting analyses indicated that mutation of the crhR gene repressed the low-temperature-inducible expression of heat-shock genes groEL1 and groEL2, at the transcript and protein levels. The kinetics of the groESL co-transcript and the groEL2 transcript after addition of rifampicin suggested that CrhR stabilized these transcripts at an early phase, namely 5-60 min, during acclimatization to low temperatures, and enhanced the transcription of these genes at a later time, namely 3-5 h. Our results suggest that CrhR regulates the low-temperature-inducible expression of these heat-shock proteins, which, in turn, may be essential for acclimatization of Synechocystis cells to low temperatures.
authors.affiliation: National Institute for Basic Biology (NIBB), Okazaki 444-8585, Japan.|Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India.
authors.forename: Jogadhenu S S
authors.initials: JSS
authors.lastname: Prakash
authors.affiliation: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India.
authors.forename: Pilla Sankara
authors.initials: PS
authors.lastname: Krishna
authors.affiliation: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India.
authors.forename: Kodru
authors.initials: K
authors.lastname: Sirisha
authors.affiliation: National Institute for Basic Biology (NIBB), Okazaki 444-8585, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Kanesaki
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan.
authors.forename: Iwane
authors.initials: I
authors.lastname: Suzuki
authors.affiliation: Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India.
authors.forename: Sisinthy
authors.initials: S
authors.lastname: Shivaji
authors.affiliation: National Institute for Basic Biology (NIBB), Okazaki 444-8585, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Murata
mesh_terms: D000064:Acclimatization / Q000235:genetics; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D015152:Blotting, Northern; D018835:Chaperonin 10 / Q000235:genetics; D018834:Chaperonin 60 / Q000235:genetics; D003080:Cold Temperature; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics*; D018869:Heat-Shock Response / Q000235:genetics; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D020365:RNA Helicases / Q000235:genetics / Q000378:metabolism*; D046939:Synechocystis / Q000201:enzymology* / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D018835:Chaperonin 10; D018834:Chaperonin 60; D006360:Heat-Shock Proteins; D020365:RNA Helicases