Effects of mutations in the rpoS gene on cell viability and global gene expression under nitrogen starvation in Escherichia coli
Effects of mutations in the rpoS gene on cell viability and global gene expression under nitrogen starvation in Escherichia coli
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DOI：
10.1099/mic.0.27012-0
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发表时间：
2004-08-01
期刊：
影响因子：
2.8
通讯作者：
Yamada, M
中科院分区：
文献类型：
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作者：
Kabir, MS;Sagara, T;Yamada, M
携带rpoS琥珀或破坏突变的大肠杆菌表现出菌落形成单位（c.f.u.）当暴露于氮饥饿时，这在具有功能性rpoS等位基因的细胞中没有观察到。c.f.u.数量的减少。在氮饥饿开始后约25小时观察到的这一点可通过在3小时内加入氮来阻止，但不能通过在氮饥饿开始后超过7小时加入氮来阻止，这表明导致C.F.U.从这段时间开始。基因芯片分析表明，大量的基因，包括许多功能不明确的基因受到氮饥饿。编码耐酸蛋白的α S和α H调节子基因的表达水平（hdeA、hdeB、gadA和gadB）、DNA结合蛋白（dps）、分子伴侣（dnaK、ibpA、ibpB、dnaJ和htpG），伴侣蛋白（mopB和mopA）和能量代谢相关蛋白（hyaABCDF和gapA），以及编码核苷酸代谢相关蛋白的其他基因的那些氮饥饿10 h后，细胞分裂蛋白（ftsL）、外膜脂蛋白（slp）和DNA结合蛋白（stpA）含量显著降低。编码转运/结合蛋白（nac、amtB、argT、artJ、potF和hisJ）和氨基酸代谢相关蛋白（glnA、trpB、argG、asnB、argC、gdhA、cstC、ntrB、asd和lysC）的基因在相同条件下显著上调，其中一些是已知的在氮限制下表达的Ntr基因。根据这些结果，可能的原因，减少的c.f.u.在氮饥饿下，
Escherichia coli bearing an rpoS amber or disrupted mutation exhibited a significant decrease in the number of colony-forming units (c.f.u.) when exposed to nitrogen starvation, which was not observed in cells bearing a functional rpoS allele. The decrease in the number of c.f.u. that was observed about 25 h after initiation of nitrogen starvation was prevented by the addition of nitrogen within 3 h but not by the addition of nitrogen at more than 7 h after the initiation of nitrogen starvation, suggesting that a process leading to a decline in c.f.u. starts within this period. DNA microarray analysis of the rpoS mutant showed that a large number of genes including many functionally undefined genes were affected by nitrogen starvation. The expression levels of a S and a H regulon genes encoding acid-resistant proteins (hdeA, hdeB, gadA and gadB), DNA-binding protein (dps), chaperones (dnaK, ibpA, ibpB, dnaJ and htpG), chaperonins (mopB and mopA) and energy-metabolism-related proteins (hyaABCDF and gapA), and those of other genes encoding nucleotide-metabolism-related proteins (deoC and deoB), cell-division protein (ftsL), outer-membrane lipoprotein (slp) and DNA-binding protein (stpA) were significantly decreased by 10 h nitrogen starvation. The genes encoding transport/binding proteins (nac, amtB, argT, artJ, potF and hisJ) and amino acid-metabolism-related proteins (glnA, trpB, argG, asnB, argC, gdhA, cstC ntrB, asd and lysC) were significantly up-regulated under the same condition, some of which are known Ntr genes expressed under nitrogen limitation. On the basis of these results, possible causes of the decrease in the number of c.f.u. under nitrogen starvation are discussed.