Surányi G, Korcz A, Pálfi Z, Borbély G
J Bacteriol. 1987 Feb;169(2):632-9. doi: 10.1128/jb.169.2.632-639.1987.
The rate of total RNA synthesis, the extent of guanosine 3'(2')-diphosphate 5'-diphosphate (ppGpp) accumulation, and the pattern of protein synthesis were studied in light-deprived and heat-shocked Synechococcus sp. strain PCC 6301 cells. There was an inverse correlation between the rate of total RNA synthesis and the pool of ppGpp, except immediately after a temperature shift up, when a parallel increase in the rate of RNA synthesis and accumulation of ppGpp was observed. The inverse correlation between RNA synthesis and ppGpp accumulation was more pronounced when cells were grown in the dark. Heat shock treatment (47 degrees C) had an unexpected effect on ppGpp accumulation; there was a fairly stable level of ppGpp under heat shock conditions, which coincided with a stable steady-state rate of RNA synthesis even in the dark. We found that the pattern of dark-specific proteins was altered in response to heat shock. The transient synthesis of several dark-specific proteins was abolished by an elevated temperature (47 degrees C) in the dark; moreover, the main heat shock proteins were synthesized even in the dark. This phenomenon might be of aid in the study of cyanobacterial gene expression.
在光照缺失和热激处理的聚球藻属PCC 6301菌株细胞中，研究了总RNA合成速率、鸟苷3'(2')-二磷酸5'-二磷酸（ppGpp）的积累程度以及蛋白质合成模式。总RNA合成速率与ppGpp库之间存在负相关，但在温度突然升高后立即观察到RNA合成速率和ppGpp积累同时增加。当细胞在黑暗中生长时，RNA合成与ppGpp积累之间的负相关更为明显。热激处理（47℃）对ppGpp积累产生了意想不到的影响；在热激条件下，ppGpp水平相当稳定，即使在黑暗中也与稳定的RNA合成稳态速率相吻合。我们发现，黑暗特异性蛋白质的模式因热激而改变。几种黑暗特异性蛋白质的瞬时合成在黑暗中因温度升高（47℃）而被消除；此外，主要的热激蛋白即使在黑暗中也会合成。这种现象可能有助于研究蓝藻的基因表达。
