A putative sensor kinase, Hik31, is involved in the response of Synechocystis sp. strain PCC 6803 to the presence of glucose.
The reason(s) for glucose sensitivity in certain cyanobacterial strains is poorly understood. Inactivation of genes encoding the putative sensor kinase Hik31 in Synechocystis sp. strain PCC 6803 resulted in a mutant unable to grow in the presence of D-glucose. Sensitivities to D-glucose, its analogue 2-deoxy-D-glucose, and fructose, were alleviated in mutants in which glcP, encoding the glucose transporter, was inactivated. These data indicate that permeation of these substrates is required to inflict cell death. The mutant Deltahik31, and the glucose-sensitive strain of Synechocystis, do not possess glucokinase activity, although a transcript originating from glk, encoding glucokinase, is present. Inactivation of glk led to severe sensitivity to glucose, indicating that the presence of glucose itself, within the cells, inflicted this sensitivity. On the other hand, sensitivity to 2-deoxy-D-glucose was lower in Deltaglk, thus distinguishing between the effect of glucose itself and that of its analogue, which, in the absence of glucokinase activity, may not be phosphorylated. Addition of glucose led to a small rise in glucose-6-phosphate dehydrogenase activity in the wild type, but constitutive activity was observed in the Deltahik31 mutant regardless of the presence of glucose. Microarray analyses showed only small changes in the abundance of global transcripts in Synechocystis following glucose addition, but the transcription levels of several genes, including icfG, but not glk, were strongly affected by inactivation of hik31. The mechanism(s) whereby Hik31 is involved in glucose sensing and response is discussed.
Kahlon
Shira
S
Department of Plant and Environmental Sciences, Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
Beeri
Karen
K
Department of Plant and Environmental Sciences, Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
Ohkawa
Hiroshi
H
Bioscience Center, Nagoya University, Nagoya, Japan.
Hihara
Yukako
Y
Department of Biochemistry and Molecular Biology, Saitama University, Saitama, Japan.
Murik
Omer
O
Department of Plant and Environmental Sciences, Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
Suzuki
Iwane
I
National Institute for Basic Biology, Okazaki, Japan.
Ogawa
Teruo
T
Bioscience Center, Nagoya University, Nagoya, Japan.
Kaplan
Aaron
A
Department of Plant and Environmental Sciences, Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D020868:Gene Silencing; D005947:Glucose / Q000378:metabolism*; D000071677:Histidine Kinase; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D046939:Synechocystis / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*
D001426:Bacterial Proteins; D003470:Culture Media; D011494:Protein Kinases; D000071677:Histidine Kinase; D005947:Glucose