Diodati Michelle E, Ossa Faisury, Caberoy Nora B, Jose Ivy R, Hiraiwa Wataru, Igo Michele M, Singer Mitchell, Garza Anthony G
Department of Biology, Syracuse University, BRL Room 200, 130 College Place, Syracuse, NY 13244-1220, USA.
J Bacteriol. 2006 Mar;188(5):1733-43. doi: 10.1128/JB.188.5.1733-1743.2006.
NtrC-like activators regulate the transcription of a wide variety of adaptive genes in bacteria. Previously, we demonstrated that a mutation in the ntrC-like activator gene nla18 causes defects in fruiting body development in Myxococcus xanthus. In this report, we describe the effect that nla18 inactivation has on gene expression patterns during development and vegetative growth. Gene expression in nla18 mutant cells is altered in the early stages of fruiting body development. Furthermore, nla18 mutant cells are defective for two of the earliest events in development, production of the intracellular starvation signal ppGpp and production of A-signal. Taken together, these results indicate that the developmental program in nla18 mutant cells goes awry very early. Inactivation of nla18 also causes a dramatic decrease in the vegetative growth rate of M. xanthus cells. DNA microarray analysis revealed that the vegetative expression patterns of more than 700 genes are altered in nla18 mutant cells. Genes coding for putative membrane and membrane-associated proteins are among the largest classes of genes whose expression is altered by nla18 inactivation. This result is supported by our findings that the profiles of membrane proteins isolated from vegetative nla18 mutant and wild-type cells are noticeably different. In addition to genes that code for putative membrane proteins, nla18 inactivation affects the expression of many genes that are likely to be important for protein synthesis and gene regulation. Our data are consistent with a model in which Nla18 controls vegetative growth and development by activating the expression of genes involved in gene regulation, translation, and membrane structure.
NtrC 样激活因子调控细菌中多种适应性基因的转录。此前，我们证明了 NtrC 样激活因子基因 nla18 中的一个突变会导致黄色粘球菌子实体发育出现缺陷。在本报告中，我们描述了 nla18 失活对发育和营养生长过程中基因表达模式的影响。nla18 突变细胞中的基因表达在子实体发育的早期阶段就发生了改变。此外，nla18 突变细胞在发育的两个最早事件中存在缺陷，即细胞内饥饿信号 ppGpp 的产生和 A 信号的产生。综上所述，这些结果表明 nla18 突变细胞中的发育程序在很早的时候就出现了偏差。nla18 的失活还导致黄色粘球菌细胞的营养生长速率显著下降。DNA 微阵列分析显示，nla18 突变细胞中 700 多个基因的营养表达模式发生了改变。编码假定的膜蛋白和膜相关蛋白的基因是其表达因 nla18 失活而改变的最大基因类别之一。我们从营养生长的 nla18 突变细胞和野生型细胞中分离出的膜蛋白谱明显不同这一发现支持了这一结果。除了编码假定膜蛋白的基因外，nla18 失活还影响许多可能对蛋白质合成和基因调控很重要的基因的表达。我们的数据与一个模型一致，即 Nla18 通过激活参与基因调控、翻译和膜结构的基因的表达来控制营养生长和发育。
