Yamaguchi Katsushi, Suzuki Iwane, Yamamoto Hiroshi, Lyukevich Alexander, Bodrova Irina, Los Dmitry A, Piven Irina, Zinchenko Vladislav, Kanehisa Minoru, Murata Norio
Department of Regulation Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan.
Plant Cell. 2002 Nov;14(11):2901-13. doi: 10.1105/tpc.006262.
Mn is an essential component of the oxygen-evolving machinery of photosynthesis and is an essential cofactor of several important enzymes, such as Mn-superoxide dismutase and Mn-catalase. The availability of Mn in the environment varies, and little is known about the mechanisms for maintaining cytoplasmic Mn(2+) ion homeostasis. Using a DNA microarray, we screened knockout libraries of His kinases and response regulators of Synechocystis sp PCC 6803 to identify possible participants in this process. We identified a His kinase, ManS, which might sense the extracellular concentration of Mn(2+) ions, and a response regulator, ManR, which might regulate the expression of the mntCAB operon for the ABC-type transporter of Mn(2+) ions. Furthermore, analysis with the DNA microarray and by reverse transcription PCR suggested that ManS produces a signal that activates ManR, which represses the expression of the mntCAB operon. At low concentrations of Mn(2+) ions, ManS does not generate a signal, with resulting inactivation of ManR and subsequent expression of the mntCAB operon.
锰是光合作用中氧气释放机制的重要组成部分，也是几种重要酶（如锰超氧化物歧化酶和锰过氧化氢酶）的必需辅助因子。环境中锰的可利用性各不相同，关于维持细胞质锰离子稳态的机制知之甚少。我们利用DNA微阵列筛选了集胞藻PCC 6803的组氨酸激酶和反应调节因子的敲除文库，以确定该过程中可能的参与成分。我们鉴定出一种组氨酸激酶ManS，它可能感知细胞外锰离子的浓度，以及一种反应调节因子ManR，它可能调节锰离子ABC型转运蛋白的mntCAB操纵子的表达。此外，DNA微阵列分析和逆转录PCR分析表明，ManS产生一种激活ManR的信号，而ManR会抑制mntCAB操纵子的表达。在低浓度的锰离子条件下，ManS不会产生信号，从而导致ManR失活并随后mntCAB操纵子的表达。
